Advice on an issue with a Moog Source

[esaeo]

Hello. can anyone think of a likley reason that my fathers Source lfo does not mod the osc's anymore? The filter is working as normal and the programs are not affected. I think it is dust on a contact that is the likley cause of the problem as the keyboard has not been used for sometime. Just wondered if anyone had any ideas?

[thealien666]

Possibly a bad contact from the membrane button on the panel...

Or it could also be a defective U18 chip. It is a CD4016 CMOS quad bilateral analog switch, found on the analog board, which can fail sometimes (not too often though).

Nah, I would think that it's more of a panel membrane button problem...The Source is notorious for this.
There is an easy fix: just replace it with a new one !

http://www.technologytransplant.com/pro ... cts_id=253

They can also be found on eBay.

[leohuppert]

Possibly a bad contact from the membrane button on the panel...

Or it could also be a defective U18 chip. It is a CD4016 CMOS quad bilateral analog switch, found on the analog board, which can fail sometimes (not too often though).

Nah, I would think that it's more of a panel membrane button problem...The Source is notorious for this.
There is an easy fix: just replace it with a new one !

http://www.technologytransplant.com/pro ... cts_id=253

They can also be found on eBay.

Hello. can anyone think of a likley reason that my fathers Source lfo does not mod the osc's anymore? The filter is working as normal and the programs are not affected. I think it is dust on a icontact that is the likley cause of the problem as the keyboard has not been used for sometime. Just wondered if anyone had any ideas?

Hi, I've just found your site. Looks like a godsend.

My questions relate to the above quote. I also have a Source (#4316) and am experiencing the same symptom as above. my unit is in pristine condition except for that one glitch. VERY low mileage. when i'm turn on the sine wave LFO waveform switch, mod works fine for the oscillator when in square wave mode, but when i switch to sine wave for a natural vibrato, it doesn't function all the time. when it goes out, it stays that way for a very long time, maybe weeks or months. then it'll work again for a short time.
So...
- does this sound like the same issue as above? and..
- have you used Technology Transplant much in the past? i see there's a membrane switch panel for sale there. any info you could give me on the background of their parts would be helpful.
- does hat sound like the right way to go for a problem such as this?

thanks in advance for your help. i cut my teeth on my mini-moog in the 70's, still own it (altho that's next in line for attention). i've really come to enjoy the Source too. i'm hoping to get it back on my gigs soon.

[thealien666]

@leohuppert

I would try first to reseat in their respective sockets U46, U48 and U49 first (on the analog board). If that doesn't fix the issue, I would then connect my oscilloscope on pin 1 of U48 and check for the presence of a slow 3 volts P-P triangle waveform.

If not, I would replace U48 and U49 and Q38 and Q39.
If on the other hand there is the presence of a triangle signal at pin 1 of U48, I would rather replace U46 with a new one. If that doesn't fix the issue still, I would then proceed to replace U47.

It is most probably not a membrane issue, since the choice between triangle and square waveforms, in the modulation section, is mutually exclusive (there is always one of the two active at anytime, and they're both switched on or off by the same button below, either for sending to oscillators or filter.)

My two cents on it.

EDIT Since a lot of the chips are in sockets in The Source, I would reseat them all carefully, just to eliminate possible intermittent contacts in the future.

[leohuppert]

wow. interesting. thanks, i'll check into that angle. it'd be great if i didn't have to replace the membrane panel. i appreciate the 2 cents!

[leohuppert]

Source repair update--
thanks to all for the good input. i found a place close to me called threewave music (threewavemusic.com), talked with the owner/tech Sam for a while and decided to leave it in his hands. he's been at this 30 +years and i immediately felt he was on top of it. he got the repair done a week early, and i was able to pick it up the day after Sandy hit here. his shop was undamaged by the storm, and if you check out his inventory, there was a LOT at stake had things gone wrong.

his rates are very reasonable, about half of nyc rates. i think i'm going to give him my model D and turn him loose on it.

and thanks to alien666. you were right on, man. U49 was indeed blown. a simple fix, and the Source is now back to original factory spec. life is good.

[thealien666]

You're welcome leohuppert. And thanks for the follow-up.

Glad it could be fixed rapidly and securely by a qualified tech in your area at a reasonable rate !

Enjoy your Moog The Source !

P.S. My bill for the online diagnostic is in the mail...