Sony STR-V55 tuner/lights fix?

BK201

BK201

Horns!
So, after the successful restoration of my AU-717 I was feelin confident and decided to see if I could get the Sony running a bit better.

Everything pretty much works except for the tuner section and front pannel lights/display.

When the unit is first turned on the lcd display flashes on and then goes out, it does not do this unless the amp was off for a while. No other lights work on the entire front pannel.
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Offset is measuring around 80mV each channel, 4 pots on amp board. Not sure where to measure bias current.
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There are tons of pots all over the tuner board. The only sound I get out of the tuner is a sort of AM buzz sound/static.
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This things doesn't seem too popular, info is scarce on the net. Couldn't find a (free) manual anywhere. Any help/suggestions would be much appreciated!
Thanks!
 

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Heres a better look at the 4 pots on the amp board.

2 pots...
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and 2 more...
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I'm guessing 2 for bias current and 2 for offset maybe? Or maybe they have no related function... :scratch2:
 

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Contact Mike at vintageaudiomanuals.com see if he can hook you up. He makes outstanding repro's..
 
Have to second that, the freebies you find on the net are usually not all that great anyways, If you are serious about fixing this unit, you might as well spend a couple of dollars for a decent service manual. The repro's are excellent.

And the correct link is vintageaudiomanuals.com :)
 
It's been a while...

Finally got around to finishing this project. Thanks for pointing me to Mike, his repro's are indeed excellent.

I traced the entire problem back to a single resistor on the amp board, swapped it out and everythings in working order. Set the DC offset and current bias we're in business.
 
SONY STR-V55 tuner fix

BK201 said:
Finally got around to finishing this project. Thanks for pointing me to Mike, his repro's are indeed excellent.

I traced the entire problem back to a single resistor on the amp board, swapped it out and everythings in working order. Set the DC offset and current bias we're in business.
Click to expand...

This is precisely the same fault as I have discovered. What was the resistor you replaced??
 
First of all, welcome to AK! :D

The resistor I replaced was on the power amp board. I believe it was R803 or R804, both are 4.7ohm 1/2 watt. PM me if you need more details.

EDIT: That reminds me, I forgot to post pics of the job, I'll have to do something about that later :scratch2:
 
Changed R804 (4R7) no difference. Changed R803 for 4R7 (but this was a 330R). Still no difference even when I replaced R803 with a 330R. Help
 
Hmm :scratch2:

I'll bust out my schematic later today and see what I can do :thmbsp:

None of the lights are working and the tuner display doesn't have power, correct? Does the power/pre amp work properly?
 
Correct. Yes, no tuner lights or display (or tuner select button), amp and pre-amp working fine.

The only problem I can see is that mine is the european model yours the US - the PCB pic's look different - therefore R803 and R804 do not correlate between our two versions. The schematic would help to see the differences and pinpoint the common circuitry.

Sorry for the vagueness, but I have NO info whatsoever on this model (user manual etc) so I am fumbling in the dark - nice sounding amp though but I would like to get the tuner going.
 
sony str-v55 tuning lights out (part trois)

i have the same problem with the tuning lights out. either of you can point me to that resistor?

thanks!
 
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