Help! No sound kenwood kr 8010

[sregor]

Do you think the leaking cap has anything to do with it?

Not likely, but who knows. The only caps that affect the protect are ck4 and ck5. ck5 would change the -19 volts, so that probably is ok. ck4 is the turn on delay cap, and would affect it only if shorted or electrically "leaky" Not likely, but who knows. Alsocap leakage sometimes leaves conductive residues which can cause problems.



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[roger2]

I can't see the base of that cap in your pic because it is a bit dark. But it is very common for larger caps to have glue around the base...more common to see that than an actual leak. If you can re-do that pic with better light or with flash it would be helpful.

Leaking electrolyte is water-like and would have some color but is partially transparent. Glue is opaque and thicker and usually brown-ish in color. More than likely it is glue. Glue does sometimes present issues as it can turn corrosive after many years. When this happens, any nearby component leads that happen to be surrounded by glue can corrode. If this happens there will be a dark green-ish fuzz around the component lead i.e. resistor or transistor leg.

 

[Bonvivant25]

Qk1 test indicated -6.8 v on collector-base. That is lower than the -11 you said it should be. So I must replace QK1.

QK2 test indicated 6.7 v on collector-base. So another bad transistor.

Qk3 test indicated -153.00 mv at collector-base. Are all three bad?

 

[Bonvivant25]

Here is a close pic. It's the brown bubble like stuff. Glue maybe?

 

[sregor]

Qk1 test indicated -6.8 v on collector-base. That is lower than the -11 you said it should be. So I must replace QK1.
QK2 test indicated 6.7 v on collector-base. So another bad transistor.
Qk3 test indicated -153.00 mv at collector-base. Are all three bad?

Not sure what is meant by collector base. Qk2 and qk3 collectors are tied together and should be the same. there should be almost no voltage on the bases of qk1 and qk2. assuming qk1 is bad, then qk3 is just "doing what its told" by qk1.A quick check would be to disconnect (unsolder) the collector of qk1 and see if relay works. (in fact, unsolder qk2 next if still no relay, then qk3. (qk3 is controlled by qk1 )

 

[roger2]

That is a better pic, but I still can't tell for certain by looking at it. If it has some thickness it is probably glue. As mentioned, glue is very commonly seen on PCB's. It is a well known thing especially in Sansuis. To see examples, google advanced search on "sansui glue" and use "audiokarma.org" in the site/domain text box. You'll probably get tons of hits to compare to what you have there.

here is an example from one of mine
http://www.audiokarma.org/forums/index.php?threads/my-au-x701.514676/

 

[Bonvivant25]

I have to redo the tests on QK1, QK2 and QK3. I was testing them incorrectly. I will do it tomorrow. I have been doing some searching online to see if I can find these transistors at a radio shack. They have some but do not have specs onlins. i found one though. So would this work for QK1:

https://www.radioshack.com/products/pnp-bipolar-transistor?variant=5717611717

It is the general one they sell. No spec sheet online so I would have to confirm that collector is in the middle.

 

[Bonvivant25]

Also, I think you are right that the substance is glue.

 

[EchoWars]

This isn't rocket science...if it's hard like dried glue, guess what?

Leaking caps leave behind a corrosive grunge a lot like the stuff that builds up around the car battery terminal. Corrosive as hell, but easily wiped away with a finger.

 

[sregor]

I have to redo the tests on QK1, QK2 and QK3. I was testing them incorrectly. I will do it tomorrow. I have been doing some searching online to see if I can find these transistors at a radio shack. They have some but do not have specs onlins. i found one though. So would this work for QK1:

https://www.radioshack.com/products/pnp-bipolar-transistor?variant=5717611717

It is the general one they sell. No spec sheet online so I would have to confirm that collector is in the middle.

That transistor should be ok for qk1. If the base is not in the center, you can get a piece of spaghetti or some insulation off a wire and slide it onto the base, and twist the leads to fit the holes. For verification, if you remove the transistor, the relay should come on if that is the only problem. Good luck.

 

[Bonvivant25]

Qk3! You little bastard! It was the problem. Replaced all three transistors and it sounds wonderful now! Thank you guys so much for all your help!!!!

 

[sregor]

 

[roger2]

Glad you got your Kenwood working

 

[Bonvivant25]

Thanks! Couldn't have done it without you guys. The most important thing is now I understand the process better.