SS amp diagnosis HELP!

[tedmich]

stereo SS amp has one channel that is dead UNTIL the vol is turned up past a certain point, then it sound equivalent to the other.....Could it be that one of the transistors is dieing?
Or the balance pot is bad? or an input connection? (its stereo) Any insight would be appreciated!

T

[Enzo]

How about a bad volume pot.

[tedmich]

could well be, its a dual ganged 50k...this thing is pretty old, its a Kenwood with one central PCB and everything else PTP; the leads to the PCB are wire wrap! I haven't seen that in a production piece since....ever. I pulled the 2 line ungrounded cord and dropped in a IEC filter and it sounds pretty good for $5

Thanks Enzo, we're all lucky you're such a fixer off, as well as on, the clock

[Steve Conner]

Wouldn't hurt to solder all those wire-wrap connections, and check the bias on the output transistors too.

[tedmich]

Solder was the first thing I thought when I saw the wrap as well, but it doesn't take flux well as its so old and dirty, I think I'd need to deoxit maybe and let dry a few days. They are surprisingly tight for their age; not one will budge. Its working very well considering, and given my son's taste in music (slammin techno) it doesn't need to sound much better any time soon. Thanks for the input all!

T

[PremiumPlus]

Wire wrap was popular back in the early to mid seventies. It actually works quite well, and I've got a Soundcraftsmen preamp/eq that uses it. The theory was that the wire would be stretched around the sharp square edges of the post and elasticity would make a permanent but easily undone connection. It worked fine and the connections still are good 40 years down the road on my particular units (I have two), but if you ever undid one you couldn't retwist it, you had to solder.