DMM modulation issue

bassist001 · February 21, 2012, 08:46:10 PM

ok, so i fixed up a newer DMM for a friend. Basically just replaced the crapy wire that was falling apart and the cheap jacks and what not. But, there was a main issue with the pedal. Basically it always has a huge warble effect going on. Even with the mod turned all the way off, the delayed signal sounds like its turned on full vibrato. Im curious if any of you have had this problem and know a fix. I checked the mod pot with a meter and it seem to be working properly

any help would be greatly appreciated!

petemoore · February 22, 2012, 06:16:57 AM

Not sure what it is, but what are they and what is it makes a big difference to somethings.

Fender3D · February 22, 2012, 06:41:45 AM

Quote from: petemoore on February 22, 2012, 06:16:57 AM
Not sure what it is, but what are they and what is it makes a big difference to somethings.

Wouldn't be easier ask for a proper schematic?

Mike Burgundy · February 22, 2012, 01:54:19 PM

If I had to guess....Deluxe Memory Man?

LirvA · February 22, 2012, 06:05:46 PM

I thought he was talking about a digital multi meter

chi_boy · February 22, 2012, 10:10:26 PM

So the LFO won't stop then? Can you de-solder the mod pot and check it out of the circuit? If you de-solder it, the modulation should stop all together. I would think you could power it up without the mod pot in without issue. Except the mod not working, of course, but it would point you in direction. Are all the IC's soldered in place or socketed? Do you have the schematic for your version?

bassist001 · February 23, 2012, 07:33:04 AM

I think I have a schematic. Im just not sure if its the right version, cause who knows how many changes they have made over the years haha but i think desoldering the mod pot is a good idea to see if it is related to the pot. as far as a visual check on everything else, all solder joints look good. I wish I had more knowledge of the complete workings of delay, so I cause tell if maybe its a chip problem. Anyone even had a chip problem? And what would happen if a chip was going bad? haha But, I try unsoldering the pot first and report back what happens. Thanks!

Fender3D · February 23, 2012, 10:50:45 AM

Quote from: bassist001 on February 23, 2012, 07:33:04 AM
... I try unsoldering the pot first and report back what happens. Thanks!

It will stop warbling, 'cause pot is just doing its job...
You won't know why modulation is always engaged though...

Schematic needed...

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DMM modulation issue