JVC tuner/amp died


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Old 10-12-14, 04:08 PM
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JVC tuner/amp died

JVC RX-662VBK Was my home amp for many years in VA, when we moved here and got an all in one surround sound I moved it to the garage and had TV and computer hooked up. Worked fine for 7 yrs. Other day I was pumping it up (William Tell Overture or 1812...not sure) and it crapped out. Both channels dead. Powers up, tuner works, source selection works, display good. Expected to find fuses or breakers on the output but no luck. All caps and xisters look ok visually, no bulged or burnt spots. Hard to test with them in the circuit.

Had amps before that blew a power amp transistor, but they were pretty visible. And since both channels went, don't think that's it.

Any hints? All I have is a good multimeter...no o'scope or anything.
 
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Old 10-12-14, 04:39 PM
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I had a similar problem with a Kenwood receiver, circa 1989. KR-V127R, awesome, about 250 watts per channel.
Anyway, I took it to shop and they fixed it and it didn't cost a fortune. No parts. I believe they said it was cracks in solder that developed over time.
 
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Old 10-12-14, 04:43 PM
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You may have blown an output transistor. The speaker protection circuit will keep both channels off if problem in one channel.
 
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Old 10-13-14, 08:40 AM
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Vic does your amp have discreet TO-3 type outputs, or a large heat-sinked chip for each channel? Often either type (but more common with chips) will have a low-value resistor in the power supplies feeding the pre-driver stage. Trace the wiring (or foil) where the unregulated +/- hit the board and you may find the first thing you come to is a .47 ohm resistor. See if it's open. Mfr's use them instead of fuses.
 
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Old 10-13-14, 08:43 AM
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Another thought...does your amp have a relay after the outputs? If so the protection circuit may be preventing the relay from pulling in due to a large offset on the output.


edit--oops I see PJ suggested that.
 
 

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