ka-5700 Help!

frankwood

Active Member
hi, I need your help to save my Kenny.

1- no sound comes out because the relay stays open
2-All the pots and switches are clean.( this include offset pots )
3- it mesures 11 volts dc at one side of the speaker relay "in".

so what's your idea? bad output? shorted resistor?

I have multimeter and some knowledge but i don't know where to began…

Thank you for your help!
 
Typical blown amp.
Typical repair process.
Test output transistors, work back through audio path testing transistors.
Test all resistors and diodes.
Replace all bad parts.
Connect dim bulb tester, pray, test fire.
If no joy, probe voltages looking for other gremlins.

Luck.
 
i have a feeling it might be around the input differentials .
p.s interesting placement of the tone circuits .
 
ok can i test the outputs in the unit? i can say i have 40volt on center pin of each 4 outputs but i have different values on the other pins…
can you tell me which pin are emit and collector?
thanks
 
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one pair of output have 3-4 milivolts at emiter; i think it's correct.
the other pair has 11volts at the emiter
so whit those readings, i don't think the output are faulty.
 
one fault might be output emitter resistors gone bad .
need to know if voltages plus or minus . you said minus -
 
outputs likely ok you seem to have lost + voltage somewhere . when i have come across similar things it is bad resistors to start with . you could compare channel for channel power off .
 
outputs likely ok you seem to have lost + voltage somewhere . when i have come across similar things it is bad resistors to start with . you could compare channel for channel power off .
i have one pnp that read bad. i have nothing between base and emit….the resistor you meen, are they big ones ceramic white?
 
i tested the other pnp and now i'm sure that the first one was bad. can i just change one or the pair? must i follow the path to diagnosis other bad component or it can be just one power output?
 
Change both. Those outputs have been out of production for years. Anything you might find labeled "NEW" is likely fake. There are modern replacements that work well, but mount differently.

It could be just the bad output.but at a minimum I'd test the emitter resistors and the drivers.
 
once again i need your help. i found new output transistor to put in. but before i must check further and i search emit resistance value. it's written MPC71 0,33 ohmk. so what it is? 33 ohms 330ohms? i don't find anything on the google bay so...confused there.
 
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