2. vintage
  3. 194603-116708

Persistent trouble with Keenwood KA-5500

Hello Agoners,

I have been experiencing an issue that seems difficult for the repair folks I use to isolate and repair.

UP FRONT:

It is not dirty pots or switches. These are clean as a whistle. No scratchiness, or dirty contacts. Please don’t say, "Clean the volume pot." It has been tested and works fine.

THE SYMPTOMS:

When I first turn the amp on, no sound until I crank the volume knob. Then it blasts on and I turn it back down. No scratchiness, just normal loud music. At that point it often works well for a bit, then sometimes, one channel will cut out, I crank the volume again, and it usually comes back. Rinse and repeat.

SO FAR: I have had it recapped, cleaned, output transistors replaced, and some broken solders repaired. 

I SUSPECT: More cracked or bad solder joints? Does this make sense? It seems like if i push enough powerl through by cranking the volume, it may be enough to bridge a bad connection, but when it cools off it gaps again. 

I am not an expert by any means, but is this a thing? Or is there another likely souce for this kind of issue?

If anyone has had similar issues, I’d love to know what the solution was. I’d like to keep the unit, as it’s pretty much the ony vintage-ish bit of kit I have left. I am willing to spend a bit to get it going "reliably" again, but maybe it’s not worth a huge expensive repair. Sounds great when working, though.

Any experience with this, or thoughts about how to address the issue?

Thank you!

 

earworm22
mm1tt77
197 posts
 

@earworm22 the only way to likely solve the mystery would be to have a technician thoroughly go through and test everything, trouble shoot until the root cause or causes are found.  It could be transistor or resistor problems, could be bad solder or cold joints as you mentioned.  Could be internal power supply issues.  That assumes the volume control is 100 % ruled out.  
 

Its age means it could be so many different things or a combination.  If you can find some experienced technicians, even if they aren’t local and you could talk to them, ask what they think based on similar receivers they have restored, repaired, they could likely give you some guidance on where to start, what has a higher likelihood of being the root cause of the issues.  Can also give you a gauge on if it’s worth going down the repair / restore route or if you are better off trading the unit in for a functioning vintage Reciever. 

ditusa's avatar
ditusa
2,070 posts
 

Toss the faulty Kenwood KA-5500 and look for a used Schiit Ragnarok Integrated amp see here. FWIW. I bought a new Kenwood KA9100 in1976.smiley

Mike

anthem55
1 posts
 

+1 on the protection circuit relay.

Post removed 
devinplombier
672 posts
 

@earworm22 

You apparently don’t intend to fix your amp yourself, so what you’re trying to accomplish here is unclear. Respectfully, if your tech is too lazy and stupid to diagnose and fix your amp, it seems a little wrong to ask folks to spend their generously donated time and expertise to do his job. What you need is a competent tech.

These amps were simple and well made, and not exactly rocket science to fix. Nice vintage piece. It deserves to be saved. Good luck!

More to discover