Kenwood KA-9100 Restoration

[Myounger]

Looking for restoration for a Kenwood KA -9100 Intergrated Amplier . Any reccomendations?

 

[ferninando]

post in kenwood forum

 

[srinath]

If it has a blown TA100 chip - might as well part it out. NLA and no good way to fix it.

Cool.
Srinath.

 

[srinath]

Ok working TA100 ? let me check, worth getting for sure, hope they do the 9600's one too.
Thanks.
Srinath.

 

[gort69]

Anybody have a way to check the TA 100?

The only surefire way I know of - and I've looked for the same info - is to solder it in to a known working amp and see if it works. Probably not what you wanted to hear. Power the amp on a dim bulb tester.

 

[CohibaJoe]

Bought this 9100, 2 7300's, 1 6100 & one trashed 7100 off of ebay, plus 2 ea. L-07M monoblocks. the 7300's are fixed, so is the 6100, the 7100 is waiting for transistors, monoblocks just arrived, this 9100 is the most difficult to fix, that is the one I want to work & of course it doesn't, has left channel working, right channel had 57 volts coming out of pin 8 of pwr amp board, (R out) replaced the TA100W & get 28 volts out, should be zero, not sure if its the TA100w or the prw. amp circuit board, replaced caps & transistors seem to check ok, will replace what I have & see if that works, not a fan of these power amp modules at all.

The 9100 is a Bitc* to work on. I was going to Recap and fix a low channel...Once I removed the front panel...look it over...I then put back the cover. It's a parts unit now.

 

[tarior]

9100s are easy to work on if you know what you're doing. First thing to look for with a voltage rail showing at the output is a failed Q5 or Q7. Usually those two just go intermittent and get noisy. TA100s are rare, so don't just replace them slapdash.

 

[tarior]

Sometimes a transistor will check out on the diode forward test with a meter, yet break down when powered. Typically they will show reverse leakage, but you have to take them out of circuit to test that.
Don't use NTE parts.

 

[tarior]

Seems like the last time I repaired one of those, I used KSA1220A.
If you're gonna work on your own gear, you will need to learn Ohm's law, Kirchoff's law, how transistors operate, how to read a schematic, how to read datasheets, and some troubleshooting skills at the very least.

 

[tarior]

Ummm....I got nothin'.

 

[tarior]

Sorry man. Your posts sounded like those of a lost newbie, or a kid who knows just enough to be dangerous. I would think that tech who does this for a living would know what a voltage rail is, or how to parse a datasheet for replacement semis.
Everybody knows that NTE parts are overpriced and pretty hit and miss, as you don't know what exactly you are getting.

 

[tarior]

I wasn't trying to hurt your feelings man.
This is a good place to learn. There are some very good techs who post very detailed reports here, what they did and why they did it, and no matter who you are, your knowledge will increase.
Also, spend some time over at DIYaudio. There are guys there who are so good that it boggles my mind.

 

[spinroch]

Please! Everyone take a milk & cookie break...

 

[gort69]

I have used the following subs with success. I'm sure I got these from an EchoWars post somewhere along the line.

Qe1-4 2sc1775 > ksc1845fta
Qe5-8 2sa912 > ksa1220ays
Qe9,10 2sc1400 > ksc1845fta
Qe11,12 2sc1885 > ksc2690ays

Parts came from Mouser or Digikey.

There is a discrepancy in the service manual for Re23,24 vs what I've seen installed. S/m states 1k ohm, the few I've worked on had 100 ohm installed. Working on one with a shorted Qe5-8(I forget which) it destroyed Re23(24). Consulting the s/m I replaced it with a 1k ohm. Did the same for the other channel thinking there was a 100 ohm there in error. On power up the relay didn't close. Measured voltage at pin 5 of the modules (pin 7,8 on PCB) and found rail voltage on both channels making me think both modules were fried. After a bit of head scratching and cussing remembered the Re23,24 deal so installed 100 ohm there and the problem was solved.

 

[tarior]

That's good to know, gort.

 

[zebulon1]

The pros who care, don’t use NTE.
Just saying.

 

[srinath]

Nevermind, urban dictionary: no longer available. Not true, u have to know where to look, just had 4 delivered yesterday from China, real part, no fake, they have more.

Could you send me a link - or what its even called. Is it TA100 ???
Thanks.
Srinath.

 

[gort69]

Here's a discussion of Re23,24 on the amp boards. I'll add that the 4 I have messed with all had 100 ohm there, as well as the 4 spare boards I have also have 100 ohm. http://www.audiokarma.org/forums/in...rd-resistor-value-wrong-contradiction.510057/

 

[tarior]

My 9150 has 100 ohm resistors at 23,24.
It looks as if it had never been worked on before I got it. During the recondition, I replaced all of the elytic caps, the trimmer, and Q11,12 with KSC2690A, and Q5-8 with KSA1220A. Nothing else on the amp boards.

 

[gort69]

Spare boards?? u should sell me one. like I said I tried a 100 ohm there with no difference in any voltages. but this board apparently has other problems that are driving me crazy.

If all else is well on that board it seems to me the TA-100 is fubar. You can solder the one from the working channel in its place to confirm. Send me a PM to discuss parts