ka-5700 no sound

Rapidroy

Well-Known Member

• Jun 9, 2014

• #1

HI All
I'm working on a KA-5700 it has no sound, all fuses are good and I pulled and checked the outputs and they check good but I'm getting some odd voltages I posted a pic of what I'm getting. I DL the manual.

 

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blhagstrom

Mad Scientist, fixer.

• Jun 9, 2014

• #2

Start at "ground zero".

Once you get a SM in hand, check the power supply voltages.

FWIW, odd voltages scattered around, or all over the place can be....
Bad ground.
Bad component leading to ground (resistor, diode, cap,...)
A messed up power regulator can make things confusing also.

 

Rapidroy

Well-Known Member

• Jun 9, 2014

• #3

the ps voltages look good, i checked the caps with my esr cap checker and so far they look good (not too many caps in this unit) poked around at the resistors and didnt find anything off (not yet LOL) oh ya the lights come on but they get power right off the ps.

 

Last edited: Jun 9, 2014

ecluser

Super Member

• Jun 9, 2014

• #4

You have no sound because the protection circuit detects the presence of a high DC voltage (-30V) at the output of one channel.

For that channel, can you measure the DC voltages at the collector, base and emitter of the first transistors (Qm7 to Qm15, or Qm8 to Qm16)?

 

petehall347

the brandy coffee man

• Jun 10, 2014

• #5

possibly a resistor/s gone high/open .
i don't see any marked as fuse resistors though

 

Rapidroy

Well-Known Member

• Jun 11, 2014

• #6

I found Q19 bad it now comes on but left side is distorted, and still getting funny voltages, but tracking that down.

 

Rapidroy

Well-Known Member

• Jun 11, 2014

• #7

well...... all fixed. I had a bad NTE290a that I installed, I was going round and round and all around Q19 (2sa850 = nte290a) went to the store and got a new NTE290a put it in and all is good!!!

 

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Last edited: Jun 11, 2014

B

bd1886

Super Member

• Jun 14, 2014

• #8

I just found a KA-5700 and KT-5500 combo and enjoyed it for a few days before gifting it to my sons friend for working on my car. Didn't do any direct comparisons to other gear of mine but it made several of my favorite speakers sing beautifully. Truly a nice amp and enjoy!