Help! The Source is killing me!!!

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MOOG_NOOB
Posts: 8
Joined: Sun Jul 24, 2016 9:02 pm

Re: Help! The Source is killing me!!!

Post by MOOG_NOOB » Thu Oct 13, 2016 7:04 pm

Sorry, I haven't checked the forum in a bit. Made a little reverse progress (read as collateral damage) during my last attempt and I had to walk away from it for a while. While replacing an IC I seemed to have created another problem...now I have very little signal and a lot of noise coming through. I have a feeling something on the synth board was unhappy with my fiddling. I'll have to chase that down, but I still have the membrane issue to fix first.

To answer your questions, I have re-seated just about everything in there that I can with no change. As for testing the membrane, I did figure out that it was a matrix and tested it accordingly. First I mapped it out and made a spreadsheet showing the working and non-working buttons...hoping it would reveal a pattern...it didn't. Then I purchased a couple of spare flex circuit sockets and perf boards and made extensions so I could plug the flex cables into these, connect to my meter and check continuity and resistance across the contacts for each button...nothing useful here either. Then I connected my meter to the leads of the diodes and resistors for each line and ran through the matrix again...both with power on and off, to make sure the button press was getting through to the rest of the circuitry...which it is. As much as I feared it was a bad membrane, at this point I would have preferred paying the $200 for a replacement.

I figured it was a scanned data/address system, just haven't figured out how to test that, so your input helps. By 'sync the scope with the read line', I'm assuming you mean trigger the scope off of the read line signal??? I'm an EE, but I'm a power systems guy so electronics and processors aren't my strong suit.

I'll probably jump back into it soon and I'll try looking at the components you mentioned (I've already purchased replacements for them anyway...just trying to minimize soldering on the board and I don't remember if these are socket mounted).

Admittedly, I haven't fully sorted through the logic side of things, but I was starting to wonder if I had a processor or RAM issue...although everything else functions so I suppose that's less likely.

I appreciate the assistance.

hanksterman00
Posts: 9
Joined: Sat Feb 20, 2016 2:53 pm

Re: Help! The Source is killing me!!!

Post by hanksterman00 » Sat Jan 07, 2017 10:35 pm

Hello
Don't know if you have resolved your issue. As with your problem I was also focused on the digital board for quite a while with the issue I had. Please refer to the post Moog Source. No Pitch/Oct Change Level 1. As it turned out there was a bad OTA IC that was pulling the address lines down. Also the schematics in this post are much clearer than most that are available.

MOOG_NOOB
Posts: 8
Joined: Sun Jul 24, 2016 9:02 pm

Re: Help! The Source is killing me!!!

Post by MOOG_NOOB » Sat Jan 07, 2017 11:57 pm

I haven't solved the problem, but I haven't given up yet either. I'll have to find the thread and go through the schematics again to see where the address lines run onto the synth board. Probably more likely for an OCA to have a problem just sitting there over the years. I'll have to go through the features again to see if I have something that is not functioning...that may help me narrow which OCA's to start looking at. Thanks again for the help.

Stevie Ray
Posts: 254
Joined: Sun Apr 17, 2016 2:25 pm

Re: Help! The Source is killing me!!!

Post by Stevie Ray » Sat Jan 14, 2017 9:24 pm

Keep us posted.

I've restored quite a few Moog synths, but all comparatively simple analogue ones (Model D, Prodigy, Rogue etc). Tackling a complex hybrid design like the Source would certainly pose a challenge for me, and all due respect to you for tackling the job.

It would be tremendous if you could bring the beast to life again, but don't consider it a failure if you can't. Some things are just beyond economical repair due to lack of technical information and unavailability of parts.

Did you ever contact Moog for advice?

I'd be interested to know how many Moog Source synths are still out there and fully operational. Not many I'll bet. It was a very cutting-edge design for its time.

electrojoe
Posts: 38
Joined: Sun Feb 04, 2007 10:15 pm

Re: Help! The Source is killing me!!!

Post by electrojoe » Wed Feb 08, 2017 5:32 pm

Hello,
What Parts in the touch panel matrix circuit have you tried so far?


GD

Stevie Ray
Posts: 254
Joined: Sun Apr 17, 2016 2:25 pm

Re: Help! The Source is killing me!!!

Post by Stevie Ray » Fri Feb 24, 2017 6:09 pm

God I hate these 'one and done' posters.

They ask for information and advice about their various projects and we offer advice, and hear absolutely nothing ever again.

I was very interested in hearing how this Moog Source restoration was progressing, but nada, zip. :(

MOOG_NOOB
Posts: 8
Joined: Sun Jul 24, 2016 9:02 pm

Re: Help! The Source is killing me!!!

Post by MOOG_NOOB » Fri Mar 31, 2017 9:23 pm

Not "done" yet, just had to walk away for a while...and for some reason I haven't been getting notifications when others posted.

I have swapped around all but one IC on the synth board for good measure. Figured it was a long shot since it seems to be a digital issue, but it was quick and easy since they're all socket mounted. Still no luck. So I'm back to the digital board, looking for something that's causing it to hang up the address or data lines.

Also have a noise issue to contend with (oops), it also seems to be on the digital board, so I need to follow the audio signal circuit to see what's unhappy there.

Going to replace the p/s caps...looks like one may be a little leaky (and I have them on hand), but the originals are still doing their job for now.

Probably spend a few late nights with the schematics and scope to see what turns up.

Strangely enough, I also bought a metal detector from the same guy. It also has a membrane switch issue...and happens to run a Z80 processor.

Any other pointers would be appreciated.

I'll try to check the board more often and provide updates.

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