Moog Source issues

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1

Hi everyone
This is my first topping

I’m about to buy a Moog source,
It has some issues

  1. The big data dial responds only when turning to the plus side
  2. The pitch wheel does not respond. The synth has a Kenton midi kit installed, and the pitch wheel does respond in midi but only turning pitch up (the seller says it might be the wrong settings in Kenton or synth itself but I’m not sure)
  3. It takes a few minutes to get in tune when being turned on.

I need some advise as wether I should order needed spare parts, (where can I find them in stock)
I hope someone can advise me on what Is needed to fix the issues

Thanks
Olutt

2

Welcome to the forum, Olutt.

Do you have any experience in electronics (as a hobbyist or otherwise) ?

If not, do you know a good qualified tech that could do some repair work for you ?

If you answered no to both those questions, I would not advise you to go ahead with the purchase.

Because, oftentimes, those “in need of TLC” bargains end up having more problems than first believed. Either by genuine ignorance of them by the seller, or by a less than honest one… :angry:

In any case, the encoder working in only one direction is an indication that one of the logic gates might be malfunctionning in the encoder part of the circuit.

The pitch wheel issue might be due to a setting on the Kenton ? I don’t know… It could also be a broken wire, or disconnected connector ?

The third item is the only one that is perfectly normal, as with many other analog synths of that era. It takes a while for the oscillators to stabilize, because they have to reach their nominal operating temperature.

So, depending on the asking price, and the questions I asked at the beginning, it’s up to you to decide to go ahead or not with the purchase.

As for buying parts for repairs, it’s very difficult to know what you would need before actually opening and starting to repair that Moog The Source…

Hope this helps a little.

Alain.

3

My Source had that issue with the data wheel. Turned out to be a bad optointerrupter on the wheel. There’s a replacement part but I don’t remember the part number. They’re tricky to replace because they have to be positioned correctly for the phase difference of the dual optointerrupter circuit to work.

4

Good point MC. Logic gates IC can still be easily found and inexpensive, but other parts are not.

5

Hi Alain,

i’m happy to be a new member

The answer to your question is Yes, i do have a qualified Tech in reach. he fixed My TB-303 and some other machines. so i trust him.

So I will need to give hime the logic gates part number and its location on the board, so there will be a better chance at fixing the issue.

As far as the purchase, the seller gave me a lower price as the synth has some issues, and these days that machine can easily reach up to 2000$ on EBay,

i paid much less than that, so i guess its a fair deal, i just need a little luck and some precious info from my new friends on the Moog forum!

so if anybody can please tell me do you know the needed Data wheel logic gates part number and its location on the board?

ill be very grateful to this forum plus another Moog will be safe to make some nice bass sounds:)

Thanks

Olutt

6

Your tech will surely have a look at the service manual and the schematics of the synth. And when he does, he will do some testing of the signals, starting with the output of the IR opto-sensor on the wheel (good suggestion by MC), before going down to the rest of the circuit, composed of mainly logic gates and flip-flops, in the Incremental Controller section.

While he’s inside the synth, he will probably also suggest to recap (replace aging capacitors after some 30 years of service). If he has done his homework and did a little research on this model, he’ll also have a look at the PSU board and check the voltage regulators (common source of problems, no pun intended) and either solder them directly to the board (removing their sockets), or at least clean their legs.

And finally, perform calibrations with the proper equipment.

7

Wow that’s lots of stuff, good thing I have your advise,

as long as I keep my Tech busy what about replacing the aging battery,

can you advise me on a good replacement?

And one more thing, are you sure the caps need to be replaced?

I’m afraid of messing around with it, I mean if it ain’t broken why fix?

Or am I totally wrong here :/?

Thanks

8

MC
That’s really useful info, I’ll make Sure my tech reads this!
If by any chance you will suddenly recall that parts name and number,from memory or documentation,
or you might get a chance to sneak a peek inside your source, I’ll be more than happy to get that Optointerruptur details , after all you replaced it yourself and that’s the best chance for me.
Anyway I’m already happy I’m in this amazing forum..
Thanks

9

Found it. You want the TCST2300.

http://www.vishay.com/docs/81147/tcst2103.pdf

Closest I could find for a datasheet for the original part (MCT8)

http://www.datasheetarchive.com/dlmain/Databooks-1/Book244-371.pdf

10

MC
That’s incredible, you made my day, I’m going to order this part, hopefully it will solve the problem all together. I’ll try ordering the yellow BRC battery too, I heard there is a better alternative but I couldn’t find out what it is, any ideas?
Thank you , this forum is a moog savior!!!

11

That battery is still made and easily available. I recommend a battery holder for the new one, meaning you want the battery with tab terminals. Check my work here

http://www.retrosynth.com/~analoguediehard/studio/keyboards/moog_source/index.html#modifications

However if you are in the states the battery cannot be shipped by air. Thank 9/11 for that.

Thank you , this forum is a moog savior!!!

You’re very welcome.

12

MC
I am located outside the US, I ordered the BR-C battery with tab holders, there are many restrictions on importing it by air due to hazardous danger, I actually needed to find someone who has a special license to import lithium metal batteries, also I ordered the TSTS2300 (3 of them) from Mouser so I’ll have spares.
The Moog will be sent to my Tech next week, he said I should defiantly recap, due to drying of old caps. Also he suggested converting the Moog from 100V (Japan) to 220V (local current) he said it’s possible.
I hope everything will work out fine.
I loved the link you sent, it’s amazing and I’m going to show it to my tech. Bravo to the forum.
Olutt.