Faulty quad lead channel

[gausshoss]

I have an early quad preamp that seems to work fine, but as it warms up the lead channel gets quieter and quieter. I've replaced the tubes but the probem persists. I even found a cold soldier joint and got excited but that was'nt it either. Is it a dried up cap? Please help! -Matt

 

[DNW]

My whole 2nd channel appears to be dead. I can get some sound from it, but not much. It's definitely not what it used to be. I thought it'd be a dead preamp tube, but that wasn't it.

 

[gausshoss]

Hey, Whats the word do we need a recap or what? -Matt

 

[4nkam]

Sounds like it could be a candidate for a recap. I recently had a similar experience with my CP preamp where the same thing happened, gain/volume loss after about a minute and the likely cause is a bad cap on the first gain stage. I just haven't had a chance to change it out yet.

MJ

 

[gausshoss]

Thanks for the input. I'll check out my first gain stage :wink:

 

[luigi]

I'd go over the whole amp with a magnifying glass. If it's a heat issue, it's very possible you've got another cold solder joint in there somewhere. It also might be a relay that starts to open up as it gets warm.

If it sounds fine when first on and gradually gets lower.....I'm thinking it's not that serious but that being said, it might be a real pain to find if you don't have something like a scope to track the signal through the amp.....where it stops is where the problem is.

BT