Ka 9100 caps

Hello!

I bought a big pile of electronics from a guy off craigslist last week. Mostly junk but one of the nice pieces he had was a KA 9100. All the pieces (over 20) were bought untested. Left Chanel on the KA9100 was dead. Cleaned the pots and boards: the channel was no longer dead but very weak. Flipping the reverse switch switched the problem, mono sounds awesome. I started looking closer and found two leaking caps on the power supply board.

Marked on the board as c12-13 Part number #CE04W1V221EL: Electrolytic 220u 35wv

Should I try to get the same caps or are there better replacements? Also: the other caps look good, but should I swap some out for better performance while I got it open and my friend is helping me out?

Sorry if some of these are simple questions. I'd search the forums but I'm not sure where to start looking.

Thanks to all in Advance!

Start with doing a search on here for a KA 9100 recap.. Very possibly someone has done one. Sounds like you have a potentially very nice amp there! From what you said it sounds like it's probably a problem in the preamp section. Definitely get good caps! Search audiokarma there is a lot of good advice on the better ones to use.

That doesn't look like leaking caps to me...rather the glue they used to hold them down during assembly. It couldn't hurt to replace the electrolytic caps, but i don't think that's your problem. I'd continue to exercise the switches and pots with a deOxit treatment, and if you have a multimeter, check the DC offset at the speaker terminals and reset the bias. IIRC the 9100 uses STK packs (or some other unobtanium outputs) whichcould be toast. Not trying to discourage you, but that's my gut feeling. If you haven't done so already, consider making a dim bulb tester before getting too far into a restoration.

The problem is probably before the amp boards and before the reverse switch if the problem switches channels with the stereo rev switch.
Also what I've found on these units is the output amp boards need a good set of robust parts, 20+ turn offset pot, there's only 3 caps and a couple diodes, fresh thermal grease on the TA100's. Those TA100w's are pretty tough .. those power supply caos look like glue but all the caps on that board get pretty hot. It's pretty tight back there and heat builds up.As far as those caps you have, if they are the same size they are probably old. The newer caps with that rating are smaller, so going up to a higher Working Voltage will increase the size of the caps to fit on the board better (feed thrus)
Good luck.
John M

PS: could possibly be a switch still. even the rev/mono sw

A little late, but the Bias on these are not adjustable. I would rebuild the whole power supply. Also, to properly clean the switches and pots on this amp requires much disassembley. Do a search and you will find much info on this amp.

Blain, I also own a 9100 and have a very similar problem to what you experience, my right channel will grow weak and cut in and out, flipping to mono and/or raising the gain and going back to Stereo fixes it for a while, but isn't a permanent fix. I've cleaned it 3 times now, I'll be following this thread and hopefully both of us can mitigate the problem. Let me know if you need help with it. Do try cleaning the Separate/Normal switch on the back as well, that can get pretty dirty because it is never moved in most situations.

jheu02 said:

That doesn't look like leaking caps to me...rather the glue they used to hold them down during assembly. It couldn't hurt to replace the electrolytic caps, but i don't think that's your problem. I'd continue to exercise the switches and pots with a deOxit treatment, and if you have a multimeter, check the DC offset at the speaker terminals and reset the bias. IIRC the 9100 uses STK packs (or some other unobtanium outputs) whichcould be toast. Not trying to discourage you, but that's my gut feeling. If you haven't done so already, consider making a dim bulb tester before getting too far into a restoration.

Click to expand...

I do also think it looks like glue, but it looks like there is way too much, I think mine may be the same way. And yes, this unit uses STK packs I believe (proprietary KW/Trio modules generally starting with TA- in the model number.

I just posted different a problem I am having with my 9100 today and was just browsing around....well way back I had a very similar issue and flipping the gain up and down would help and deoxit would cure it for short periods. I eventually tore it down and replaced the gain switch and it has been perfect since. I had feeling the gain switch because of the force in which its gets flipped up and down it caused the whole switch assembly to create a solder joint issue thats why flipping it corrects it sometimes. I had a replacement switch on hand just in case and installed it but i was sure it was just a solder issue. there is only 1 other switch on the 9100 that is identical to the gain and i forget which one, but they have part numbers on the side, That is a serious pain job to do just so you know....but you will be happy with the results. I havent had a sound issue since.....and this amp produces serious power.....well worth the time spent fixing.

Did you make sure to clean the pre/main connected/separate switch? I got my 9100 cheap with a dead channel and it ended up being that switch causing the channel loss.

Edit: after further reading, sounds like Pionner! beat me to it. GL with your fix