Kenwood ka-9100 help

i would measure the collector of Qe7 on the working amp and compare with your board. looks like it should be 1.15v and not 34v you are measuring. Pin 3 on the ICe3 might be easier to get to.

did you replace Ce13/Ce15? those voltages look off too. Plus you are measuring 49v on a 16v cap. Yikes. Makes me wonder if ICe3 is working to get 49 v on pin 4.
 
Good to hear JG - makes you wonder how many 9100s have been scrapped thinking a TA-100w was bad when it was something else....
 
i would measure the collector of Qe7 on the working amp and compare with your board. looks like it should be 1.15v and not 34v you are measuring. Pin 3 on the ICe3 might be easier to get to.

did you replace Ce13/Ce15? those voltages look off too. Plus you are measuring 49v on a 16v cap. Yikes. Makes me wonder if ICe3 is working to get 49 v on pin 4.

Hi finally had some time today
I removed the small ceramic caps and the voltage is about the same
The collector of Qe7 is 35v also have 32v pin 7 of Ice3
Ice1 2.7 v on pins 3 & 5 should be .8 v think Ice1 is bad ?
 
C44DBAA4-C5D9-48EA-BE72-9BF5BB8E907F.jpeg Hi again
Was able to score a parts ka-9100, both channels appear to function but relay does not engage.
Removed the amp board and recapped it.
C44DBAA4-C5D9-48EA-BE72-9BF5BB8E907F.jpeg
Will replace q9 when the next mouser order gets here
Also got a new tool, Hakko de soldering tool.
3C1F43B9-A99E-46F5-AD63-745BD18EBFEC.jpeg
Really like it, made short work of the 4 big caps

734C0D3D-238B-419F-99A2-B94A002AC900.jpeg

Will be replacing the 12000 uf 63 v with the reccomended 10000uf 63 v solder tab caps, would have preferred the 15000uf but twice the money, has anyone done that ?
After 24 hours 3 of the big caps still had 45v while one had 12v. Looks like one of the caps is having an issue
016F90CB-7267-4008-833F-132E83F5A79E.jpeg
 
HI
I am back on the 9100 again. I have recapped and replaced all transistors on both of the power amps. I have also replaced the trimpot with a multi turn unit. But it looks like I may have introduced a problem. The amp powers up and plays fine (sounds great) but I am unable to adjust the off set voltage. I can get the voltage to about .004 volts but its swinging around like crazy +- .070 volts. Both amps are doing this, but the left channel is worse, also its getting pretty warm. I have checked voltages on the transistors and they are about what I would expect, with the exception of Q11 collector voltage (also tied to pin 9 of tw100) its swinging around quite a bit as well -1.2 v +- .7 volts. I had replaced Q11 with C2690A-Y. Thinking about putting old Q11 transistor back in, but its a pretty warm day in the lab... Any suggestions ?
thanks
 
Main filter cap link: https://www.mouser.com/ProductDetail/Nichicon/LKG1J153MKN?qs=sGAEpiMZZMtZ1n0r9vR22SV4CH/%2butB%2b9QcVT5Iv%2bWCGsekoD045KQ==

Other main filter cap link (requires minor dremeling of filter cap mounting slots): https://www.mouser.com/ProductDetail/KEMET/ALT22A153DE063?qs=sGAEpiMZZMtZ1n0r9vR22fqp084l1X3er8GMABHdfi0=

Are the voltages on amp board test point pins 5 & 6 (+57Vdc), 11 & 12 (-57Vdc) solid, or jumping around? The collector of Q11 is tied to pin 7 of the TA-100, not pin 9. Pin 9 is a ground.

HI
Thanks for the links
The +- voltages look good, I have a donor amp board (non modified) that seems to work fine. Your right, don't know what I was thinking Q11 is tied to pin 9.
 
Thanks I will check. What’s really odd is if I select the back switch to separate the amp and preamp the offset voltage becomes rock solid. I can connect my MP3 player to the power in and it plays fine.
 
Thanks I will check. What’s really odd is if I select the back switch to separate the amp and preamp the offset voltage becomes rock solid. I can connect my MP3 player to the power in and it plays fine.

Not meaning to bust in your thread but I just tried connecting my tablet to my ka-9100 like you mention and I have relatively clean sound, but the volume control & balance don't work. With the switch in Normal, I barely get sound on the right channel with a lot of static & popping. So does this give me a starting point of where to start looking for an issue ?

Again, Sorry for bust in your thread.
 
Hi
Sounds like your might have some dirty pots or switch’s, a good deoxit job should clear it up, search this site on how to clean the ka-9100 switches, they can be hard to clean. You might want to start a new post to get more exposure, lots of folks willing to help here
Good luck
 
Not meaning to bust in your thread but I just tried connecting my tablet to my ka-9100 like you mention and I have relatively clean sound, but the volume control & balance don't work

That's because the volume and balance (and all other controls) are in the pre-amp section. "Power in" is only the power amp, so make sure whatever you connect there has a volume control or else your speakers and ears will take all the power the amp can deliver.
 
You sure on that? If so, I'd replace them with KSC1845
HI Gort69
Thanks I don't know why I put the C2690's in, I had ordered the KSC1845. I replaced them tonight and It looks like the amp temps is lower now, I was seeing 130 deg on the TA 100 and now its down to 100 deg. But I am seeing 200 mv voltage swings on the speaker outputs with the volume at 0. Switching the amp to separate amp/preamp the voltage is rock solid. I connected a scope to the preamp outs and didn't find any strange high freq signals. Every thing seems to function otherwise tone, volume, loudness etc and it sounds great.
thanks again..
 
One thing to check is see if there is AC riding on the +/-57 Volts (High Ripple)
AND check R23 for open.
OR the 24volt zener.
 
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Just wanted to post that I finally got one of the KA-9100’s finished and working great
EADF10A4-DD69-4A6B-8C5F-6773C37711D0.jpeg

Still trying to sort though the 2nd 9100. Did complete recap and get popping sounds out of the speaker when turning off, also having wild voltage fluctuations when adjusting the DC Offset, voltage problems go away when preamp is disconnected though.
 
Hi all,
Just want to post that I have found the final problem with this unit and wanted to post my solution hopefully helps someone else.
Problem was unable to do center voltage adjustments because of large voltage swings. 2nd problem was a thump from speakers when powering off, both problems went away when unit was set for seperate power/preamp switch in the back. This was after complete recap. Otherwise the amp seemed to work fine. I found +35 and -37 on the power supply board pins 23 & 25, supposed to be +29 -29. This power is for the preamp board and is not used by the power amp. Also saw lot of noise with the scope on - side. Traced it back to Qk2 emitter, noise was also on the base, replaced Qk4 with ksa1220a and everything starting working fine, voltage dropped down to +29 -29, and was finally able to do center adjustments. Very happy now, thanks for all the help.
Pic below of Qk4
8F3C3B34-D2FC-40C3-BCD5-FB09105A98F7.jpeg
 
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