Dyna Comp sensitivity problem

Started by alec eiffel, March 09, 2013, 08:34:46 PM

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alec eiffel

Hello all,
I'm relatively new to building/repairing electronics and new to this forum.  It looks like you guys mostly discuss building, but I have a repair question and figured this might be a good place to ask.

I have a '78 Dyna Comp and the sensitivity knob doesn't seem to be working as it should.  Adjusting it will still compress the signal, but it also distorts..and not in the good way.  I was curious to see if anybody might know where a good place to start looking for the problem would be.  I've had luck repairing pedals in the past, but the problems were easier to identify.  I was thinking that maybe there is something that need to be replaced since its over 30 years old.

It also might be worth mentioning that when I received the pedal from a friend, it wasn't working at all.  I opened it up and the battery was from the early 90's and the insulation to keep the circuit board from touching the enclosure had melted onto the board and the pots.  I cleaned it off as best I could and replaced the insulation with piece of plastic a la Boss style pedals.  It was working fine for a few months and sounded SO good.  so much better than the new dyna comps.  It would be a shame to have to retire this pedal.  Any help would be great.  Thanks!

petemoore

I was thinking that maybe there is something that need to be replaced since its over 30 years old.
  Electrolytic capacitors. 30 years they might be due now or anytime soon for sure, but they might not be what the problem is either...
  Taking voltage measurements allows better diagnosing.
  Also the debugging page [audio probe etc.] is so often instrumental for locating bugs !
Convention creates following, following creates convention.

alec eiffel

thanks for your input.  replacing the caps would have been my first guess, too.  i need to do a little bit of research on how they should register on my DMM and i'll give it a shot.  the info on some of the caps is a little bit faded so i'm have to figure out exactly what i need to replace them if that's actually the problem.  i'll report my results.