Wednesday 1 June 2016

Minimoog Replica



In the next few weeks I'll be reporting about my new project of building a Minimoog Replica. I have already started researching options and ordering some of the rarer parts. I have found various sites on the intertubes of people who have already built their own. Some even offer PCB layouts to copy, print and etch.

Here are the sites that I relied on most.

Clonage du Minimoog by Crazy Patroche
He's published on his site very nice PCB layouts in PDF form that match closely those of a Minimoog. I used these to make Gerber files so I can send them to a PCB manufacturer (I don't etch my own PCBs). Patroche uses the "newer" VCO that contains very rare and very expensive components.

By the way, Patroche gave me permission to post the derived Gerbers on this site, which I'll do as soon as I find they're OK.

Building a Minimoog Model D Replica by Tauntek
This is quite a detailed report on the construction of a Minimoog, electronics, case and all, including some details that I could not find anywhere else. For his replica he used the "older" VCO that uses the CA3046 transistor array. I'm using the same one.

Moog Minimoog (export) by FantasyJack
The essential site with all the schematics and parts list copied from the service manuals. Don't even think of building a Minimoog without consulting it early and often! There are also a few pictures of a disassembled Minimoog, especially boards, that are helpful when tracing a PCB or constructing a Minimoog cabinet.

Minimoog by Arpeggi8
Not quite as detailed as the other sites, but a great inspiration anyway with fine, detailed pictures of the cabinet.

Minimoog Wiki by J R
Quite a detailed build log, essential notes and an indispensable parts list (with substitutions).

Minimoog Resources on YuSynth (Yves Usson's site)
...especially the cabinet dimensions.

Mini-Modules : Minimoog DIY clone on its way by Julien Delgoulet (on MuffWiggler)
This has become quite an extensive post on MuffWiggler, but an essential read nonetheless. Some of the transistor substitutes (see below) were proposed by Julien.

Incidentally, Julien's about to offer a collection of PCBs and a Eurorack frontpanel for his Minimoog clone. But, of course, you can always forego the panel and hide the PCBs inside a nice vintage Minimoog cabinet.

Components

I intend to build my replica as closely as possible (or reasonable) to the original. This means using original components when they are still available, and other parts that look like those on the pictures of the Minimoog PCBs, even if they are a bit more expensive. When in doubt, I follow the pictures.

Transistors

Some of the transistors used in the original Minimoogs are obsolete and cannot be found with reasonable effort and/or expense. They are substituted with similar devices. Here's a table of all transistors used in the schematics, and possible substitutes and sources.

DeviceSubstitutes (reference)Source
2N3392still availableTayda Electronics
2N34152N3904 (original schematics), 2N3392 (Patroche)BGmicro
2N4058still availableMouser
2N4303BF245 (Julien), 2SK30 (Patroche)
2N4402still availableSmall Bear Elec, BGmicro
E402LS3954Aebay, Micross
MPS-U05TIP31C (Patroche)Tayda Electronics
MPS-U55TIP32C (Patroche)Tayda Electronics
TIS922N3904 (parts of orig. schematics)
TIS932N3906 (parts of orig. schematics)
TIS97MPS8097 (Julien)Mouser

This table gives a range of possibilities to choose from. When the original schematics offer substitution options, of course, I'll take these. For some of the TIS92/93, substitutes are specified in the schematics, but not for all of them. Still, I think it's safe to substitute them all. For the remainder, I happily rely on the advice and experience of others.

Some of the substitutes have different pin-outs than the original devices. Luckily, the original PCBs have appropriate labeling on the solder side indicating which hole represents which pin. These labels were present in Patroche's PDFs, and hence also converted into my Gerbers. Still, care will be required when stuffing the PCBs.

Also, you need to be aware that some of the transistors need to be matched in pairs. Therefore order a few extras so you'll have enough to select from.

Resistors

In the schematics, 1/4W resistors are specified in some of the units, and 1/2W in the power board. However, in the bill of materials (the ones in the service manual), all carbon film resistors are 1/2W units, as are apparently those in the pictures (size matters sometime...). So I ordered 1/2W ones for all of them. They're cheap anyway, at least on Tayda Electronics. Some rarer values are not stocked there, however, and are much more expensive to order from Mouser or Digikey. But luckily, there's only a few of them.

Capacitors

Most modern circuits used in the DIY community use radial capacitors that use very little real estate on a PCB. This one uses axial instead. There are not that many capacitors, but some of them are quite rare in axial form and hence quite expensive (especially tantalum capacitors).

The filter board uses two 30nF polystyrene capacitors. The biggest value I could find so far was 10nF. That means wiring 3 of them in parallel. Fortunately, there's plenty of space on the boards.

PCBs

I've finished tracing the VCO circuit (that I was unable to find on the intertubes) from a picture of the board -- or rather two of them. Indeed, I had to manually compensate for the lens distortion in order to get right angles, and then arrange the two pictures so that the traces meet where they need to. After a few attempts I got an almost perfect fit, which is why the board came out reasonably well.

To convert the resulting circuit to Gerber files, I exported the graphic as PDF and then used my hand-made PDF-to-Gerber converter program to generate Gerber files (bottom, outline and solder mask only). There were a few issues with the software that I had to fix along the way, but eventually, I got very nice Gerbers of all six circuit boards. Presently (02.Jun 2016), they're off for production at EasyEDA.

8. June 2016
The full set of PCBs has finally arrived! On the picture starting from the top left we have the oscillator, the filter/VCA, then on the second row the small rectifier, the tiny octave buffer, then the dual contour and finally the power/noise board. Some of the components, especially the resistors, have also arrived earlier today, so I could technically start soldering now.


However, there's another shipment arriving later this day (the switches, the card edge connectors and some other items from DigiKey). I think I can just barely hold off until that's arrived, too.

I forgot to mention that I went to the post office today to fetch a package that could not be delivered yesterday. That's the fourth package in a single day, a new personal record! It contains the 15nF polystyrene capacitors that I finally managed to find and buy on ebay. They'll simplify my building the filter board a bit (see Capacitors above).

12.06.2016
I started stuffing the boards with the resistors that I have (that's almost all of them. A few are still in transit from the moon. Futurlec, I'm talking to you!!). Anyway, thanks to the nice layouts by Patroche, all resistors have a common 15mm spacing, which allows bending the legs using a bending gauge utility. Nonetheless, stuffing the boards is a tedious task because (a) the boards don't have silkscreen on top (like the original boards), (b) there are a lot of different values and (c) some of the values given in the replacement lists are wrong (here's Tauntek's errara list) or have been updated as "factory mods". It's a good idea to cross check with images of original stuffed boards once in a while. Working over my original VCO layout that I posted on the Electro-Music forum was a good idea, too, because now that all components align properly, it is quite obvious which holes belong to which resistor.

Meanwhile, I'm finalizing my orders with Mouser (mostly parts that can't be found anywhere else), Musikding (cheaper than Mouser but limited catalog) and Reichelt (whatever remains). I decided to go with the look'n'feel of the earlier boards. These have colorful tropical fish capacitors for certain polyester values instead of the boxy-types of later boards (see Crazy-Patroche for pictures). Some of the boxy-values are expensive or non-stocked at Mouser. Lump-types (as I call them) are always cheaper and more readily available, and while being not as colorful as tropical fishes, at least have a similar lumpy shape. That's good enough for me (and, no, I won't paint them). I'll make a list of component sources once I have them all.

Tip-of-The-Day: When ordering stuff, be sure to double- and triple-check your cart before sending it off. I ordered too few red rocker switches (3 instead of the required 5), which will lead to an expensive follow-up order with shipping cost far exceeding parts cost.

13.06.2016
I've finished soldering those components that I have (resistors, diodes, jumper wires) and made a picture to show off. When soldering resistors, I do the "factory mods" described in the service manuals, which is why some of the values differ from those in the parts lists. I follow the pictures on FantasyJack where you can clearly see that they've got the mods, too (if you know, where to look, that is).

VCO (top) and Dual Contour boards, partly stuffed

I do have some of the transistors (2N3392, 2N3904/6) that I need, but I'm unsure whether it's a good idea to solder them now, i.e. before the less delicate components such as the remaining resistors, capacitors etc. are in place.

The friendly people at DigiKey allowed me to amend a pending partial order, so I'll have all rocker switches without an additional follow-up order.

18.06.2016

Oh Futurlec, ye online shoppe,
How hard just can it be,
Whatev'r it is you do to drop
and send those parts to me!


I'm still juggling orders between retailers in order to save shipping costs (big ones like Mouser offer free shipping above a certain minimum amount) and/or moving parts between shopping carts when a certain value is (temporarily) unavailable at a certain retailer. It also seems that certain parts or values are unobtainable with reasonable effort. Here's a (potentially growing) list of parts that I'll have to substitute and hence deviate from the original design.

5M #1 Taper Potentiometer (Glide pot on front panel)
I could not find any reference as to what a #1 taper potentiometer actually is, but Tauntek has measured[PDF] the taper curve, and it seems pretty close to an audio one. Incidentally, on image 9-17 of the service manual -- the wiring diagram -- R2 is specified as 5M audio pot. Unfortunately, those aren't obtainable either (Mouser, DigiKey, eBay). Finally, I've given up searching and will take a 1M audio pot instead. A welcome rationale is given by the friendly people at CAESound:
Glide pot note: We have substituted to the 1 Meg value from the stock 3 meg. We found that this works very well. Our survey says that almost no one ever used the Glide pot set to maximum Glide time. Therefore the Value of 1 Meg will work for 99% of all players.
That's good enough for me.

05.07.2016
The order from Futurlec has finally arrived, and I have already started soldering the resistors in place. The VCO that I'm using requires 2 sets of 3 matched resistors, one of 51.1k and one of 15k Ohms. I'm not quite certain as to what degree I have to match them, but I guess when my brand new DMM does not show any difference between them, that's close enough. Unfortunately, I forgot to order enough 15k units, so I don't get a close enough match. I'll add a few more to the Tayda order that's in the queue.

I also checked the 15nF polystyrene capacitors that I found on eBay (see above) and discovered that they are 10% values, when I actually need 2.5% tolerance. I measured the devices using my DMM and found four that are just about within the 2.5% margin, especially when I pair them up to get the required 30nF. I'll take my chances and use them anyway.

Tomorrow, I'm finally going to match transistors. There's just no way around that, if I ever want to finish the synth. I'm going to follow the procedure and use the circuit by Ian Fritz which seems easy enough. Luckily, I still have the circuit somewhere on a breadboard. Also, I have ordered plenty of MPS8097s (TIS97 substitute) and 2N3392s, so I'm confident to find a few matches.

07.07.2016
I've finished matching NPN transistors (MPS8097 and 2N3392) and found enough devices that I can use. Indeed, I bought 30 transistors of type MPS8097 at Mouser and found their VBE to be within +/-2mV of each other with only a few outliers. After setting up a current of 100µA, I was able to match 6 of them pairwise to less than 0.1mV. As for the 2N3392 that I bought at Tayda, I found those that I tested to be all within less than +/-1mV which is a bit suspicious. I didn't expect to find a match after testing 3 devices. They have a different pin layout (ECB), but I checked and re-checked several times. Nonetheless, I'll build Ray "Music From Outer Space" Wilson's transistor matching circuit and check all matches again just to be on the safe side. What remains to do is to find two NPN/PNP pairs, one of them matched to +/-3mV at 20mA, and the other one such that the VBE of the PNP device is 10mV to 20mV lower that that of the NPN at 200mA. I'll try using Ray Wilson's circuit to measure the devices.

07.07.2016
There appears to be a small controversy about the transistors in the VCF ladder, and whether they are matched or not. I thought that they need to be matched but then found that those transistors specifically mentioned in the parts list refer mostly to different ones. Page 2 of the Moog Factory Service Bulletin 804C[jpg] (Synthfool Minimoog Docs), which amends the notes on page 9-9 of the Minimoog Service Manual (the VCF schematics) lists those transistors that need to be matched, but again these are not part of the ladder:
Change note 3 to read:
  Q26 and Q28 are matched to ±3mV Vbe at 20mA IC.

Add note 5:
  Transistor pairs: Q5 & Q7, Q13 & Q14, Q15 & Q16,
Q27 & Q33 Vbe matched to ±4mV at IC=20mA.
In the schematics, the bottom pair of the ladder (but only the bottom pair) is marked with a small M in a circle, apparently indicating a matched pair (and, indeed, Q29 and Q30 are matched). Also, in some of the pictures I have of the filter PCBs, the ladder transistors are marked with a color dot (see the VCF on Patroche's site), indicating that they are "special" (as in "matched").

Here's what I'll do: Given that the matching target above is rather generous -- so much so that I think nearly all the transistors I have lie within that range -- I'll use the ones I already did for the ladder and then match 4 more pairs for those listed above in the "add note 5".

What bothers me a little, however, is the requirement for one of the complementary pairs (NPN/PNP) to be matched at a collector current of 200mA. This is pretty much the absolute maximum rating of the 2N3904/6 (substitutes for TIS92/93). The datasheet shows the TIS92/93 to have a higher maximum rating of 800mA, so the required matching current is well within their limit. Perhaps it's sufficient to match the pair at a slightly higher current, say 50mA (one quarter of the maximum rating), to have a pair that's at least partially consistent with the original. Fingers crossed!

20.07.2016
I'm building a variant of the Moog transistor matcher circuit (with a few additions suggested by Ray Wilson). While I believe that most transistors' VBE are well within the limits required for the different circuits, I want to check some of them again. When I redid some measurements to find a few additional matches for the VCF, I found completely different values for the matches that I already had. Perhaps I blew a few transistors when plugging them into the breadboard. I don't know. In any case, I can't trust the matches I have, so I'll do them again but in the traditional way by measuring the VBE directly and then find close pairs.

Electronics Enclosure

I've started planning/building the cabinet of the synth. I bought an (expensive) aluminium sheet in my local DIY store for the front panel. It's only 1.5mm thick instead of the original 0.063" = 1.6mm, but I hope that's not a problem. I sawed it by hand into shape, i.e. 7" x 27 ⅛" (plus 1cm on either side for the bent-down wings). Sawing the long edge was a problem, because my hacksaw does not "reach" far enough into the sheet. I had to saw from either side until the saw frame hit the sheet, and then used a blank sawing blade that I held with gloves to saw the part between. It was ugly but I finally managed to complete the front panel. I'm not quite sure yet how to bend the wings or all the flaps on the side sheets (see pictures of the insides linked above).

I test fitted one of the switches that I bought by cutting a rectangular hole in one of the aluminium cutouts and drilling countersunk holes for the screws. I saw that the specs for the switch were tight, but not that tight.

How to mount a rocker switch using standoffs (left 1cm, right 9mm).
How NOT to mount a rocker switch using standoffs.
In short, the mounting holes are useless, because they are too close to the switch. Or my spacers and my screws are to big. I don't know how Patroche managed to fit his (see picture [scroll down] of his front panel). Blimey!

20.08.2016
It's been a while since I updated this build log, but I had a few other projects to tend to. I'm not finished with the PCBs yet, because I still need to match a few transistors (see above ). Also, I had to order a few additional components that I don't like the look or quality of. I found on eBay another couple of 15nF polystyrene capacitors, but they have not arrived yet.

In the meantime, I started with the enclosure (by the way, I'm doing several things in parallel, so this log may at times become a bit messy. Once I'm finished, I'll make a PDF document that will record the whole construction in a more sensible order). I built a bending rig to bend my aluminium sheets (why does autocorrect suggest "aluminum". I'm not mercan...). It worked somewhat well for the two heat sinks for the power supply board, but was totally overwhelmed when I tried to bend the front panel wings: the hinges were bent and torn out. That spells trouble in all caps, when I have to bend the length of the sheets that make up the sides of the electronics enclosure. I'll have to come up with a design different from the original.

While we're at it, I also ruined a plank of wood when I tried to plane it down from 17mm down to 15.9mm ( the metric equivalent of 5/8 inches). At my DIY store I can't get the right thickness, so I'll have to pay a visit a local carpenter.

So many words to report so little progress.

21.06.2017
I've been busy working on a couple of different projects, including a video series on music electronics, but now I'm back. I still haven't decided yet on the metallic enclosure for the synthesizer, so I proceeded with the wooden cabinet in order to get started again. I've finally found a plank of 15mm thickness at my local DIY store and decided that this was close enough to the original (according to the published cabinet dimensions). It will make the synth a bit lighter without making much of a difference visually.


I started by sawing -- by hand -- the two cheeks at the side of the cabinet. By keeping the saw vertical and carefully cutting along the line, I managed to get straight cuts at the proper angles. Because the cuts were done by hand, the cheeks are almost but not completely identical. I hope I can sand them to size. I don't have any decent woodworking tools, and the cheeks showed clearly the limits of what can be done by hand. So I built a jigsaw table that would allow me to do the longer cuts for the remaining cabinet pieces. I'm still making mistakes and ruin lumber galore, but the cuts are certainly straighter and faster to do. So far I've got the cheeks, the back piece with a beveled cut and a glued-on bottom bar, and the trim piece going to the top of the front panel. All the pieces have the occasional scratch and blemish that I'll either be able to sand away or have to attribute to it being a vintage synth, after all.

06.07.2017
I've finally managed to complete matching transistors, so I can finish soldering all the circuit boards. I built a permanent version of both Ian Fritz' simplified transistor matcher and a version of Robert Moogs circuit based on the Dragon Fly Alley adaptation (using a TL071 and an additional capacitor as suggested by Ray Wilson). I re-tested the matched 2N3392 (used in the contour/keyboard board) and found them spot on. I then proceeded to find additional matches for the MPS8097 (TIS97 substitute), so I can use matched transitors for the ladder filter. Nearly all of them lie generously within the requested margins (worst pair is less than 0.2mV apart with 4mV being acceptable).


Matched transistors ready to be used. A few leftovers in the bag. Coffee hard earned (and well deserved).
Indeed, all transistors I have are practically matched to one another within a few tenths of millivolts. This made it quite hard to find the one pair where the VBE of the PNP needs to be "10mV to 20mV lower" than that of the NPN (contour/keyboard). I had to revert to earlier orders and my small inventory to finally find a pair that is 12mV apart.

I think regarding how far manufacturing technology has evolved since Robert Moog's times, you can probably just grab a pair of transistors from the same batch and be fine i.e. have an acceptable match. Anyhoo, I'll use what I have and then decide on the electronics enclosure to finally begin the tedious wiring process.

10.07.2017
I'm nearly finished soldering the boards. The only thing that remains is the tempco mod that Yves Usson of yusynth.net describes on his Minimoog page. It consists of moving the three tempco resistors closer to the transistor arrays that they are supposed to control the tracking of. That should take no more than a few minutes. Oh, and I still have to push the ICs into their sockets. That's another five to ten minutes.

I've also figured out -- finally -- how the electronics enclosure is built in the original Minimoog. By inspecting the interior pictures on fantasyjackpalance.com (and also reading Tauntek's page word by word) I discovered, that the bottom part of the enclosure (where the PCBs are slot into their sockets) is attached to the front panel using a piano hinge, allowing it to "swing" up and down a little, presumably to give access to the card slots and the wiring. The whole enclosure is then attached to the case using another piano hinge. Because there is only one row of mounting holes along the bottom of the front panel, it appears that both hinges are mounted there: one is mounted "inwards" to attach the bottom of the enclosure to the front panel, and the other "outwards" in order to mount the front-panel-plus-enclosure to the wooden frame. The bottom piece of the enclosure therefore needs only one long bend (along the edge opposite the hinge) and two short bends (one on each of the short edges). I should be able to do that -- fingers crossed. After all, Tauntek was too, apparently.

Update

Done! The boards are finally complete. I haven't yet fixed the tempcos to the transistor arrays (note the flying white wires on the VCO board), but I'd call it a milestone anyway.


I may also have found a way to attach the switches to the front panel (see discussion above) by using a narrow brass tube that is narrow enough not to interfere with the switches' operation. But not today. I'll have a beer now, cheers!

14.12.2018
Here are the Gerbers of all of the PCBs seen in the pictures above.

Before you proceed to download, here are the terms and conditions, that you agree to by downloading the Gerber files.

All PCBs except the oscillator board were designed by Crazy Patroche. He kindly gave permission to publish the derived (by me) Gerbers of his original PDF designs. So thanks go to him alone.

The oscillator board (CA3046 version) is my design. I traced it by hand from a pair of pictures. Therefore it looks different (more square and less professional). All blame is mine alone.

I made the Gerbers automagically by converting them from the original PDFs. Based on these, I had the PCBs manufactured at EasyEDA (now JLCPCB). They were accepted, so they seemed to have worked. You may have to alert them, that the strange "grilles" on the oscillator boards are intentional.

The PCBs have no silk screens. You need the original PCB layouts and parts list (especially the assembly scans and parts list further down on the linked page) to complete the build. Cloning a professional instrument is an expert-level project. If you can't be bothered to research and look it up, don't download the files.


112 comments:

  1. hello
    can you write me at patroche26@yahoo.fr ? i have a question
    best regards
    patroche

    ReplyDelete
  2. Hi. Will yor gerber files be for the 3046 VCO, or the uA726 one?

    ReplyDelete
    Replies
    1. I did the 3046 ones. The uA762 are very hard (as in "expensive") to get your hands on.

      Delete
  3. And also, do you know the exact brand and model of the overload and pilot lamps?

    ReplyDelete
    Replies
    1. Oooooh, I'm not sure if I do the overlord (he he..) or pilot lamps. I might quietly replace them with LEDs.

      Delete
    2. Thanks. I await those gerbers.

      Delete
  4. Hi Ralph. Your minimoog boards look awesome, do you have any PDF/Gerber files available for these?

    ReplyDelete
    Replies
    1. The PDFs for all boards except VCO are available at Crazy Patroche's site (see links on top of posting). I'd like to check the proper functioning of "my" VCO before releasing either PDFs or Gerbers.

      Delete
  5. Good to see you back on track!

    ReplyDelete
  6. Great work! Could you explain me why there are those strangely corrugated tracks on the osc board?
    Are them some sort of tuned cap? (The ones that look like pcb antennas they use today, to say..)

    I'll keep following! Please upload the new pcb!!
    Can't wait to hear some sound sample :-)

    Marco

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    Replies
    1. They are 10pF capacitors! If you go to FantasyJack (see links on top) and then check the schematics of the "Old VCO" you'll find in the notes at the bottom that the C* caps are "etched on the circuit board".

      Honestly, I have not the faintest idea if they work at all. Also, the PCB manufacturer alerted me that there were some holes missing there... :-)

      Delete
    2. I like them! Cannot wait for your updates!

      Delete
  7. Hi, i'm building my own replica of the model D. Same osc card (3046) easiest to find.
    Did you finish yours...?

    ReplyDelete
  8. Any chance you can release the PDF files for impatient folks like myself? I'm also building a clone using Julien's board. I may be further along with the constructions than you are :-D

    I'm considering etching the real boards myself since I've found where to buy the edge connectors. I hope to hear from you about this! Best wishes!

    ReplyDelete
  9. Are you any closer to releasing the CA3046 version of the Minimoog Gerber files. Incidentally Resynthesis.co.uk has switches and knobs etc for the Minimoog. Thanks a lot for the information you have provided here.

    ReplyDelete
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    1. This comment has been removed by the author.

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  10. It's been over 2 years since this page has been updated. I'm not sure if Ralph is still involved in any DIY electronics community. It would have been great if he released the files as is so others who have the time could check his work. There's a layout of the same rev 2 board so it's a matter of checking to see if the traces match. I'd hate to have to lay out my own boards but at this point I don't seem to have many options.

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  11. Thats a shame hes not doing it anymore, as you say just rease them as is. I'm new to dit etc so I certainly wouldnt know how to layout a circuit fram a shematic. I have some CA3046's thats why I was curious about the other revision boards. Has anyone made the 2n4906 versions, I'm amazed that those components work but mind you the old crows version has readily obtainable new parts and that sounds pretty good. Keep us updated if you do anything else with this. Cheers

    ReplyDelete
    Replies
    1. The 2n4906 verson? No such thing - only used where the origional schematic shows. The big substitute is using MPS8097 instead of the TIS97. The Minimoog Eurorack (MME) that was mentioned on this page is more true to the original design than old crow's circuit. I've already completed one of those and it shows how it can be easy to obtain the parts for the 2nd version of the oscillator board (the one used on this page). I have all of the parts for a true replica and only need to bend some metal, etch the boards and wire it up. Which is why I'm bummed out that we aren't hearing from Ralph. Hope all is well.

      Delete
  12. I've nearly finished my own layouts of this same project. The only difference is I've rearranged the pins for the substitute power transistors on the power board. Anyone interested in etching their own replica boards please feel free to email me at kevinmleclairjr@gmail.com I'll have the transfer layouts (not gerber) and BOM for the electronics and cabinet hardware.

    I hope to see an update to this webpage. It's a shame to go so far, have the boards fabricated and then bench the project without notice.

    Happy holidays
    -KM

    ReplyDelete
  13. Really useful information thanks. Hope you get the chance to finish it one day. I tried downloading the gerbers but the link to 'Old Oscillator Circuit Board No. 1' is pointing to the
    'Octave Buffer Board No. 6'.

    ReplyDelete
  14. It’s great to see updates here! The only thing holding up my project is the chassis construction. I have all the information and none of the tools. Feel free to contact me if you need any assistance with measurements or parts.

    Looking forward to seeing your finished work.


    -KM

    ReplyDelete
    Replies
    1. Just starting my own preparations for a build. Currently checking over all the Gerber files and adding a silkscreen and plate through-holes.

      Which version of the Oscillator board are you using? I am thinking about using the UA726 board but with something like a Portabellabz pA726 as an alternative to the pricey UA726's. Do you know if there are benefits to one board over the other?

      Thanks,
      Matt

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    2. I went with the CA3046 version since it was way easier to source the parts and also I was already familiar with it after building the MME.

      I can’t comment on the differences or preferences between the boards. But the CA3046 one is much more popular. Even the reissue models used that same design. I’m sure you can find an archive of comments from people who have played both.

      Shoot me an email for details on my project. I literally have every bit of it but the metal chassis. I’ve ruined my panel trying to bend the ends with my primitive tools and decided to wait until I have proper metal working gear or find a reasonable fabricator who’d work with me. Honestly that’s the most frustrating part to undertake (a warning to Ralph if he’s not prepared)

      -KM

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  15. This comment has been removed by the author.

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  16. This comment has been removed by the author.

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    1. This comment has been removed by the author.

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    2. Ahhh, I really should have read more carefully. Of course the links at the bottom are to the Gerbers. Thank you very much.

      I really appreciate the work done here! I'm so excited to get this project off the ground!

      Delete
  17. If I may, what specifications should I list when ordering the boards? Is there anywhere you can redirect me to figure out what the necessary dimensions, thickness, and build of the PCB's are?

    ReplyDelete
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    1. Also, taking a look at the gerber files, I see that only 4 layers are used. I read that you noted these PCB's have no silk screens - does this mean I must compensate for this in some way? Or am I safe to just send these gerber files to a manufacturer and receive back the correct PCB's?

      Sorry for the endless questions - I am young and very new at all this :)

      Delete
    2. I have tired uploading the files to jlcpcb.com and they are accepted but will not load in to the Gerber viewer, so i cannot be 100% sure they have imported correctly.

      You could use the standard settings they offer though. It will automatically enter the dimensions for you. You can pick a different colour board if you wanted of course. Stick with 1.6mm thickness so the boards will fit in a 3.94 mm card edge connector.

      I am currently going over the Gerbers and adding a silk screen as well as some through hole plating.

      I tend to use Chinese PCB fabs as they are crazy cheap. If you use a more local (and way more expensive) place they do tend to offer more support and check the layouts are as expected.

      Most of the Chinese fabs have a minimum order of 5 per PCB, so I wonder if there is some scope here for a group buy? I imagine it would be around £30 per full set of boards + P&P. I only want 2 sets so will sell on the other 3 anyway.

      Delete
    3. Hi!

      Is it important that I have a silk screen layer that isn't already in the gerbers? If so, do you mind sharing what you come ups with? I would try to do it myself but I am completely new to all of this, so having the files ready to go would help a lot.

      Also, what manufacturer are you planning to use in particular? I'd be interested to know.
      Thanks!

      Delete
    4. Hello,

      No it is not important, you can get them made without a silk screen. The original boards do not have one. I prefer to have one as you can see where all the components are supposed to go and it looks good ;).

      I will be happy to share the Gerbers once finished sure.

      I use jlcpcb.com . Very good quality boards and the cheapest I know of.

      Delete
    5. That would be fantastic! I think I would prefer the silk screen as well for labelling purposes. I am having difficulty organizing my parts list - so if a silk screen could lay out for me exactly what I need, that would be immensely helpful.

      Thank you so much. Good luck on your project!

      Delete
  18. Hey Matt,
    I was going to ask if anyone was getting any fabed and had some spare to sell.
    Let us know if you get some done.
    I'm currently following Kevins project also because he has kindly given PnP type pcb traces for the boards for diy etching which is ofcourse cheaper again but I will be interesed to watch this space to see how much a pro board set would be.
    Cheers

    ReplyDelete
    Replies
    1. I am still working on the Gerbers at the moment but will get some made soonish. Probably be a month or two before I have then in hand. Will let you know. I have a 3/4 finished Yusynth modular on the bench behind me too but got side tracked!

      Delete
  19. If Ralph doesn't mind... Here's my spreadsheet with part values and some vendor information. I've just added photos of my home made boards. I'm sure it'll be of great use. The documents will be polished up as I find time.
    https://docs.google.com/spreadsheets/d/1uTNWPULbq07FmUdAW3LTaJJMa69QbfvR27P0nwhXP6c/edit?usp=sharing

    Remember guys, don't bite off more than you can chew. Best of luck!

    -KM

    ReplyDelete
    Replies
    1. Amazing spreadsheet! Was going to start one myself but no need anymore. Are the component references as per the service manual PCB layouts?

      Decided on the CD3046 version. Found some audio samples and scope shots and prefer the CD3046. Your right that it is by far the more popular verson.

      Delete
    2. Yes they are in reference to the factory schematic. I've copied the BOM and cleaned it up where necessary. I'm still picking at my receipts to list the parts I've decided to use. I've included some observational notes but did it for my personal build - it's not as pretty as I'd like. However it's a great resource for anyone who takes on the clone project. I wanted to save enough information so that I may repeat the project in the future.

      Soon I'll add the specs for the cabinet and chassis build.

      -KM

      Delete
    3. To clarify, these parts will fit the schematics in the six gerber files posted above?

      Delete
    4. Yes. Essentially it's the same thing part for part so long as it's a copy of the original. However Ralph did use different trimpots than I had. I went with the ones used in the reissue model while he chose Piher brand ones that are a bit larger.

      -KM

      Delete
    5. I noticed you used 1/4 W for the resistors. A lot of the originals were 1/2 W. Do you think this would make much difference? I do remember reading someone saying it would effect the sound but I don't know enough to make that assumption.

      Delete
    6. Only for the metal film - as did Ralph. The difference is my choice matches that of the original design (old photos show RN series labeled on the resistors) You'll see they look right in my photos. 1/2 watt RN series are way to big. I've learnt that the hard way.

      Tolerance effects the sound. Voltage rating does not. They just need to be well enough to not burn out. And they shouldn't.

      -KM

      Delete
    7. There is a video from Mioogfest 2016 where they discuss the importance of using the right resistor to get the right sound. I recall what you're referencing, but I'm not positive if it's 1/2 W.

      Delete
    8. I know from experience they are not 1/2 watt metal film resistors. I've used the same exact ones they had. Without matching certain resistors or using 1% where specified the oscillators will not be in sync. Luckily the schematic and other references elaborate on where resistor tolerance and matching is necessary.

      Don't believe everything a salesman throws at you. I've already cut my teeth with this circuit and some of the things they say is worth a chuckle.

      -KM

      Delete
    9. @KM DId you check the pinout of the voltage regulators on the power board (pics in spreadsheet)? The TIP31/32 have different pinout than the original MPS-Ux5. On my board I had to cross the pins using wires.

      Delete
    10. Hi, Ralph. It's good to hear from you. I've explained this in a previous comment.
      "I've nearly finished my own layouts of this same project. The only difference is I've rearranged the pins for the substitute power transistors on the power board."
      I'll also add I've used different trimpots and made some routing changes for that as well.

      Delete
    11. Is the MPS8097 transistors you used on the filter bd a better match to the TIS97s than the suggested 2N3904s?

      Delete
  20. As I'm organizing my parts list, I have a few questions that could be answered:

    - For resistors, I only need to worry about the correct tolerance, resistance, and wattage, correct? Unless otherwise noted, termination style doesn't matter, and should I worry about the material type (carbon build/metal build/carbon composition) or the temperature coefficient?

    Sorry for the newbie questions - I am researching parts based on key phrases such as "2.2M 10% resistor" and there's so many other qualifications to worry about.

    Thanks!

    ReplyDelete
    Replies
    1. You are correct. Tolerance, resistance, and wattage are the main things to consider. Don't mean to state the obvious but make sure they are through hole too.

      Out of interest, do you have much electronics experience? This is quite a project for your first rodeo!

      Delete
    2. This is indeed my first rodeo. I'm a freshman in college looking for a substantial project to do, and this seems incredibly fun. I'll make a lot of mistakes but I'm determined to do the best I can! I'm trying learn as much as I can.

      More than anything right now, the organization/preparation process is crazy. I constantly have a billion windows open on my computer and I'm trying to make sense of what exactly I need to get. Getting that right seems to be harder than making the circuit itself haha.

      Anyways, all the help I can get is appreciated. I am lucky that two other people are working on it at the same time, and with much more experience than me. It would be great to keep in touch!

      Thanks :)

      Delete
    3. You're asking for trouble! lol.

      Please try out the MME first. You'll learn allot and it's very well documented. The thread over at muffwiggler has a great deal of resources. The questions you are asking have been asked and answered over there.

      Trust me, there's a reason why there's only 2 or 3 known working clones of this thing.

      -KM

      Delete
    4. I've taken an extensive look at the MME. And you're definitely right, I probably should start with that one.

      However, I've gone into this understanding I won't be nearing anything close to 'working properly'. The margin for error is so unbelievably small, and given I'm a beginner, that's bad news. That's alright with me though, part of the fun is seeing how far I can take it with very little experience. I've been taking online courses on circuitry on the side as well, so I'm starting to understand the way things are routed. I know that isn't nearly enough, but this project is the challenge that really captures my attention, so that's what I'm going with.

      I appreciate your guys' words and advice!

      Delete
    5. Upon second thought, I won't purchase the MME kit, however you are right that giving the tutorial a look would definitely be beneficial. I'll check it out today. Thanks!

      Delete
  21. Should I use 1/4 W for all resistors? Or should some boards use 1/2 W? I see that some posters have strayed from the original factory schematic of 1/2W.

    ReplyDelete
    Replies
    1. Above in the resistors section Ralph mentions "In the schematics, 1/4W resistors are specified in some of the units, and 1/2W in the power board. However, in the bill of materials (the ones in the service manual), all carbon film resistors are 1/2W units, as are apparently those in the pictures (size matters sometime...). So I ordered 1/2W ones for all of them."

      Different builders have gone different ways. Some have used 1/2 W throughout, some 1/4 W. The key thing is the wattage rating is there to prevent them burning out.

      The 'bill of materials' that people refer to is actually a replacement parts list, not necessarily the parts list used during manufacture. Schematics are always your best source of information. I am using 1% metal film 1/4 W throughout (stopped buying 5% carbon film as the price difference is nothing these days and it means I only have one resistor collection). I inherited a large quantity of 1/2 W so might use those in the voltage reg, amplification sections just to use them up.


      Delete
    2. I'm updating my BOM today. You can use my references if you want it to be like the original. Otherwise you could use whatever you can get your hands on.

      Matt is correct on the wattage suggested. 1/4 watt should work all around but might not make the cut for parts of the power supply board. It all depends on the current demand being pulled through the regulator circuit. The worst that could happen is a few fried resistors over time. Better to be safe than sorry, right?

      -KM

      Delete
    3. In the interest of long term performance, say a few resistors eventually get fried over time. Is it possible I can simply replace the resistors with a higher wattage resistor, or would the circuit be permanently damaged? I assume the answer has many variables, but I'm trying to make the best decisions now to prevent such a thing. As of now I'm finding 1/4 W resistors for everything except the power board, like Matt is doing.

      Delete
    4. It is unlikely any of them will get fried in these circuits. You are not dealing with very high wattage at all. Usually it is just a case of replacing old for new. Personally I would be checking the entire board over in case there is a bigger issue than the resistor just over heating. That burnt resistor might have just saved one of your more valuable components!

      Delete
    5. It's hard to know but I'd say if any resistors fry out you'll be able to tell something is wrong quickly, apply fixes and all should be okay.

      I said the RN series 1% 1/2 watt are too big. The 1/4 watt 1% RN series resistors in my BOM are the right ones. I highly suggest you stick with the factory specs. But you could use the smaller metal film like Ralph had used along with 1/2 watt carbon film for the rest.

      If you're stumbling on resistors I fear the complexity ahead of you. I suggest you get the most difficult part of it out of the way such as the cabinet and chassis. If and when you get those done the rest will be a cake walk and a sprint to the finish line. I'm not trying to discourage you. I just hope you understand the complexity ahead.

      You could build the MME and convert it as a couple people have already done. That's far less complicated and the BOM is very straight forward.

      I'll say it again and I mean no offense - don't bite off more than you can chew.

      -KM

      Delete
    6. Awesome, I've just decided to go with the specifications listed on the original BOM, as modeled in Kevin's spreadsheet. I won't be too worried then if wattage isn't exactly correct for some things. I'll just make sure tolerance and Ohms are identical.

      I've noticed that Kevin said all 1% tolerance resistors should be from the Vishay RN60 series. For ease of purchase I'm not going to worry about getting that exact manufacturer and series. I just need to remember that "matched" implies I should order a quantity of two instead of one, which is the listed amount in the original BOM. Is this correct?

      Delete
    7. Also Kevin, in regards to the cabinet, I have my uncle who is a woodworker helping me out building that part. I'll probably head over to his shop during the summer. Besides, I have a document with the exact specs and dimensions of the cabinet as well, so I'm hoping that part won't be too bad.

      You are right that the chassis will be difficult. I'm going to look around and see if I can get help from someone else with building that part.

      Delete
    8. You have much to learn, Cooper.

      Matched resistors need to be matched to about .1% with each other. Take the 1k ohm 1% matched set of 4 for example. The tolerance implies that the spec of each resistor will be 1% within the given value. So they won't read exactly 1,000 ohms but rather between 995 and 1,005 ohms (1% of 1,000 is 10). Matching them to .1% would mean they can't be different beyond 1 ohm. So randomly picking 4 1% resistors will not be good enough. My BOM notes that I had purchased 20 and got 4 that measured close enough to .1% tolerance. But to be frank - that was a bit of luck that within those 20 4 were close in value to eachother.

      Alternatively you could source .1% rated resistors and not have to worry about measuring and matching. I've done that with my MME build.

      The above was explain the the MME thread at muffwiggler as I once asked this question myself.

      Please send me a direct email at kevinmleclairjr@gmail.com and I'll happily burden you with everything I've learnt about building one of these.

      -KM

      Delete
    9. ahhh was just about to hit publish and your beat me to it! ;)

      I often just go for 0.1% just to save all the faffing about.

      What document do you have for the cabinet? Is it the Yusynth one?

      Delete
    10. That PDF is great but does not mention that the front and back (page 4 and 7) are each two pieces glued together. You'll also have to consider how you'd mount the keybed that you use since you very likely will source an alternative that doesn't fit like the old ones in an original unit. Also - almost every keyboard made today uses a diode matrix so you'll have to plan on sourcing or building a controller. I've built my own and programmed a microcontroller - sending a signal to a DAC to send out 1-volt per octave and trigger signals to the synth. Plan ahead! Just an FYI.

      -KM

      Delete
    11. Was thinking about doing something similar, I also have a couple of MFOS Single Buss 1V/Octave Keyboard controller boards somewhere.

      Delete
  22. Thanks! I'll keep an eye on your spreadsheet. I'm likely going to go with the 1/4 W for all but the power board then. I would go with 1/2 W all around just to be safe, but as Kevin noted above, sometimes they don't fit the board.

    ReplyDelete
    Replies
    1. Just to note... I've said the RN60 1/2w series are too big. The 1/4w are perfect and what I suspect is what they had used for the 1% resistors in the original and reissue models according to my observations of detailed photos.

      -KM

      Delete
  23. Hi Ralph. I have just started my own Minimoog build and would like to know what kind of trim pots did you use? Based on a measurement I did in my Gerber viewer it seems that the trim pot pin spacing is about 12.7 mm x 10 mm but I am not seeing any 100 ohm trim pots on Digikey or Mouser with similar pin spacing.

    ReplyDelete
    Replies
    1. https://www.reichelt.com/gb/en/setting-potentiometer-horizontal-15mm-100-ohm-pt-15-l-100-p14949.html?&trstct=pol_4

      I believe these fit if you want to use the original footprint. I, like others and Behringer, have altered the pcb to use much smaller modern 2.54 x 5.04 mm trimmers.

      Delete
  24. Hi Ralph. Could you please release your PDF to Gerber tool to the public? The only tool that can do the same is called FAB 3000, which is very expensive. There is also a Perl script script called pdf2gerb, but that is a command line tool and has no sexy GUI like yours. Thanks in advance ;-)

    ReplyDelete
    Replies
    1. The new version of eagle cad will let you convert Gerber files to board layout.

      Delete
    2. I have my custom Gerber files I made but never used so they are untested. I ended up getting a Boog in the end. My files have silkscreens and I added and some modifications for headers and use of modern trimmers.

      Delete
  25. Does anyone know if it would hurt to use 1% resistors instead of the 5% resistors on all the main boards.

    ReplyDelete
    Replies
    1. Nope it's fine. The purists might not agree but it won't effect the functionality.

      Delete
    2. Yeah it wont hurt. I am using 1% as replacements for some of my 5% just because that's what I had. I am actually almost done with my clone now minus any troubleshooting I may need to do in the end.

      Delete
    3. What kind of trim pots are you using for your boards. The 25ohm on bd 1 is of interest.

      Delete
    4. I ended up getting the multiturn (I think they may be 25 turn) trim pots and I had some "adapter PCBs fabricated by JLCPCB so that the newer pots could fit on the older pot footprints of the PCB gerbers provided on this blog.

      Delete
    5. Here is the 25 ohm trimmer that I got.

      https://www.mouser.com/ProductDetail/652-3296W-1-250LF

      Delete
    6. How critical is it to use a 25ohm vs 20ohm that is single turn flat top like this https://www.mouser.com/ProductDetail/652-3386P-1-200LF

      Delete
    7. It is generally ok to go bigger with trimmers but not smaller. With smaller ones you could find yourself in a situation where you dont have the range available to make the necessary adjustments.

      Delete
  26. This comment has been removed by the author.

    ReplyDelete
  27. Does anyone know if the MPS8097 transistors some have used on the filter bd are a better match to the TIS97s than the suggested 2N3904s?

    ReplyDelete
    Replies
    1. With a quick glance at the datasheet it looks like the MPS8097 is a slightly better alternative mainly due to it having a more matched range of Hfe values (about 250-800), whereas the 2n3904 can go lower than 250. This could cause some minor issues with buffering and loading if the 2n3904s are used instead but I'm not sure if it's a huge deal. I actually dont remember which I am using for my boards off the top of my head but I might go for the MPS8097 to be on the safe side if I were in your shoes.

      Delete
    2. Actually yeah, for the filter board specifically it could cause some issues to use 2n3904s and I think I did use the MPS8097 for those.

      Delete
  28. Thank you for the quick response. NOW. What is the best circuit to use for matching the transistors? Moogs or another? I plan on ordering 100 pcs to get the closest matches I can.

    ReplyDelete
    Replies
    1. Moog's is fine, use it along with a decent multimeter. Layout the parts away from radiators and windows. Don't use your fingers.

      Where you getting 100 from? Hope it's not China 😲

      Delete
  29. I'm getting them from Mouser. Trans are made by Central Semiconductor. I'm not familiar with them, but I trust Mouser.

    ReplyDelete
    Replies
    1. 100 should be enough to find adequate matches from my experience.

      Have you planned any of the construction for the cabinet or chassis (being the most difficult part of cloning the thing)?

      Delete
  30. That's another long story. I am probably the 1st person to build a clone of the Mini. I built mine back in 1977 as a science fair project. Robert Moog showed interest in me than and sent me 10-1 blueprints of all 4 main boards (which I still have). I laid out with drafting tape, had the boards photoed and reduced. Had a circuit bd mfg locally make the bds. Ordered all major parts from Moog at discounted price back than and made me a set of boards. Talked with I forgot who now at Moog and was given the ok to purchase a used keyboard and broken cabinet from them for $150.00 ($100.00 for cabinet and $50.00 for keyboard). Robert Moog said he would help me but he did not want to see my clone mini in any of his repair centers for repair. My board are old and were not the best quality even back than so I've laid out new ones and want to make a new set of boards.

    ReplyDelete
    Replies
    1. That's a good story! It's great that you had drawn Bob's attention.

      I missed out on a used cabinet & chassis on ebay last year. All I need is the chassis!

      I may have a friend in a couple mechanical engineers that may help me out (my 3D modeling is worse than my free drawing lol). I'll add all documents to my build spreadsheet - you'll find the link in one of these comments.

      Best of luck! I've been nearly done for over a year ;)

      Delete
  31. I may have the only actual mini without a serial number.

    ReplyDelete
  32. I think if I had to do it all over again I would make the ctrl panel in 1 or 2 circuit bds like the new revisited mini.

    ReplyDelete
    Replies
    1. For my 2nd build (perhaps years from now) I do plan on drawing up my own panels and using current production switches that are found in the reissue. I had decided to go vintage as there are reproduction panels available that were designed around the old/original parts (old switches and 5/8" bushing pots). Next time when I have all of my own CAD drawings finalized it will resemble the reissue.

      Delete
  33. Thought I would share that I am finally about finished with my minimoog clone (at least the sound portion, I still plan on building a custom MIDI controller for it). Now I didnt do a full enclosure clone since I didnt have the time nor the resources for that. Instead I opted to buy a premade 5U 19" rackmount enclosure and drilled out all of my necessary holes. As such my mini doesnt have a built in keyboard and will instead be fully reliant on MIDI control.

    Just today I worked out all of the bugs in the oscillator board. I used the gerbers provided on this blog, and will probably post a list of all the problems with the oscillator board gerber here at some point once I get the chance (just a single trace cut and a few solder bridges).

    The oscillators are awesome and the filter sounds gorgeous. I am so excited to now have my first analog synth. I have kept my process fairly documented and am currently planning on making a video detailing that process and posting to YouTube at some point.

    Thank you for this page and the information it provided.

    - Ryan

    ReplyDelete
    Replies
    1. That's great news! Excited to see what you've got going there!

      I'm back at it and writing out testing procedures for the board. It'll be little while before the documentation is complete but for now I've got the oscillator testing done - just need to confirm and add scope shots.

      Added the link to page one of my spreadsheet
      https://docs.google.com/spreadsheets/d/1uTNWPULbq07FmUdAW3LTaJJMa69QbfvR27P0nwhXP6c/edit?usp=sharing
      -KM

      Delete
    2. HI Ryan , Have ordered PCB for osc. from jlcpcb.
      I noticed your post:

      Just today I worked out all of the bugs in the oscillator board. I used the gerbers provided on this blog, and will probably post a list of all the problems with the oscillator board gerber here at some point once I get the chance (just a single trace cut and a few solder bridges).
      Can you post details , it would be a great help.
      Best regards.

      Delete
    3. I will see what I can do with that after work today!

      Delete
    4. Here is a document showing all of the oscillator board corrections. There are a total of 5 corrections to be made: 2 trace cuts, and 3 bridges. My board has these and works perfectly now!

      https://drive.google.com/file/d/16hPkqwMRf6s4ZSvRaEkiS9aFQvu0ZWti/view?usp=sharing

      -Ryan

      Delete
    5. I saw your YouTube build video and have been inspired to build one of these as well. Boards are on their way and the first batch of components have been ordered.
      Can you share your MIDI controller design or the resources you used to design it?

      Delete
  34. Please can you tell me if you can email me the pcb layout as I want to make my own boards?

    ReplyDelete
  35. Hello I'm the one that built the mini back in 1977. Got my boards up in working order with the exception of board 2 (keyboard circuit). I can not get it to track. When you turn it on everything is fine but when you press any key the pitch goes high and stays there no mater what other key you press afterword. I had this same problem with my first board back in 1977 and ended up buying board 2 from moog. I can get everything working with the original moog board for now but would like to find out whats up with my new made board. I have swapped all major components from moog bd to new bd and put the new components on the moog bd.
    The moog bd still works great but my bd does not. Checked for the 8.5ma at keyboard string as well as voltages through out. Transistors have been matched where needed. Any one else have this problem? By the way I found 3 problems with my osc bd and one on the filter bd. Glad to here that you are working on yours again.






    ReplyDelete
    Replies
    1. Hi , i have just ordered the complete set of PCB's and would be keen to know more detail of the 3 problems with the osc board and the 1 with the filter board.
      I hope you can assist.
      Best regards

      Delete
  36. Hi Ralph,

    Could you share the source code of your PDF to Gerber tool? Thanks in advance ;-)

    ReplyDelete
  37. Hello,
    good morning
    I am French,
    Since my teenage years I have loved the MiniMoog with the DEVOs.
    Today I'm making one...
    I made the PCBs a cardboard facade.
    but i'm stuck on 3 problems
    so i have a few questions
    how do you do for the connectors and fixings of the PCB?
    do you have the cabinet plans?
    have you kept the plans of the metal box?
    there is still a lot of work to do...
    regards
    Alexis

    ReplyDelete
  38. When mimimoogvis buolt you neef to play replicad by tubeway army

    ReplyDelete
  39. Hello dear friend, how are you? Im trying to replicate the Model D at well, and Im doing this with protoboards! The rectifier and Power Supply went OK:-) as well as pink, white and red noise, so I was optimistic about my next challenge: the oscillator...so, I built them, but I couldnt "see" any wave at the oscilloscope, (most important the 0V~-4V wave at the collector of Q9, 2N4058...).., so, my question is: how I could test the oscillator properly? I put the -10V, +10V and the -5V power lines, and the -4V as well, but there was nothing. I have to put some signal at the summing lines inputs as well (4A, 5A, 6A, 7A, 8A, 14A )? I have to build the oscillator buffer board and the resistors/ switches, only for the purpose of testing the oscillator? Please, if you have some schematic that I could test the oscillators, one by one, I will be forever greateful!!! I spent so much at components at Mouser, Im stucked at this point, and here in Brazil we pay a lot of taxes as well...happy New Year! :-) Daniel...

    ReplyDelete