The Source OSC2 Triangle wave missing

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Freeks
Posts: 6
Joined: Tue Mar 06, 2012 3:09 pm

The Source OSC2 Triangle wave missing

Post by Freeks » Wed May 04, 2016 4:06 am

Hello,

I got my Moog The Source membrane changed to new one while ago. That fixed all the problems i had with The Source. Now i noticed that i can't get triangle wave for OSC2. If i select Triangle i get Saw dew db's louder than the normal Saw wave.

No idea where to start to troubleshoot this. Any ideas?

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noddyspuncture
Posts: 421
Joined: Wed Sep 16, 2009 7:57 pm

Re: The Source OSC2 Triangle wave missing

Post by noddyspuncture » Wed May 04, 2016 6:15 am

You'd need the circuit diagram and an oscilloscope for starters...!

Cheers,
Tom

Freeks
Posts: 6
Joined: Tue Mar 06, 2012 3:09 pm

Re: The Source OSC2 Triangle wave missing

Post by Freeks » Wed May 04, 2016 6:55 am

I have the circuit diagram, but no oscilloscope. How do i know is the problem in the membrane that sends wrong command or in the circruitry?

spiders
Posts: 26
Joined: Thu Feb 19, 2015 2:11 am

Re: The Source OSC2 Triangle wave missing

Post by spiders » Tue May 10, 2016 2:31 pm

The membranes are much more solid than the internet would have you believe. They do stop working, but that is due to oxidation of the ribbon cables in most cases, I would suspect. That was certainly the case with mine, and I've found threads where the great Kevin Lightner indicated the same. I revitalized the ribbon connectors and the membrane works as good as new. It is highly unlikely that your membrane is sending the wrong signal to the source. The membrane is basically just a bunch of switches, no robot thoughts reside in there.
It is possible that it is not plugged in securely, that can certainly cause problems. You should verify that the source is registering the signal from the membrane. When you press the triangle button, does the red edit light blink? If so, the membrane is working. If no, try reseating the ribbon cables. Gently. They are not super sturdy, at least the old ones.
I'd point my attention at the op amps / transistors in osc 1 on the schematic. Taking a quick look at it, it would appear that U30 is a major player in the triangle game.
good luck.

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