help with dbx 160vu

[fandusss]

Hey guys,

I'm having an issue with a dbx 160 vu that I was hoping someone else here has experienced and can help me pinpoint the fault.

I'll try to explain the issue: once the compressor has been set appropriately, it will randomly increase its gain reduction to around about double the amount initially set. This also lowers the output accordingly due to the extra compression taking place.

This issue also rendered the threshold pot useless, as once the fault occurred the pot would no longer have any effect. This led me to believe maybe the pot had issues, so after checking with a multimeter I saw the pot was behaving strangely. I pulled all the pots apart and cleaned their internal surfaces.

Now where I'm at is the gain reduction fault still randomly occurs, but the threshold pot now works during the time where the fault is present.

Any ideas of what to look for next?

Thanks guys

 

[shot]

Maybe you could check ICs. Especially TL082a located in the middle of the board, near the bunch of diodes. This one is in before and after treshold pot. If it is faulty it could oscillate. And check solder points and if it's legs are fitted correctly on it!

 

[beatnik]

rms detector is also very prone to failure

if has never been done before, change all electrolytic capacitors. and check all soldering on pc board

 

[deafgarrin]

Yea in the RMS the LM3083P 16 pin IC are what usually fail!