Hi All
I have a Proton 520 Amp Sound from left channel is slightly distorted.
I noticed transistor Q613 BC640 PNP that drives a Toshiba 2SA1094 heats up in about 4 second it can not be touched its so hot. I measured B= -1Volts, C= -31V
E= -0.3Volts
The right channel transistor Q614 BC640 is fine, measures the following B= + 0.6 Volts
C= - 31Volts , E= + 1.2 Volts.
I don’t have a schematic without it, its pretty hard to find what causes the problem.
I removed both BC640 transistors and swapped them, the problem remains.
Any suggestion
Thanks Allan
I have a Proton 520 Amp Sound from left channel is slightly distorted.
I noticed transistor Q613 BC640 PNP that drives a Toshiba 2SA1094 heats up in about 4 second it can not be touched its so hot. I measured B= -1Volts, C= -31V
E= -0.3Volts
The right channel transistor Q614 BC640 is fine, measures the following B= + 0.6 Volts
C= - 31Volts , E= + 1.2 Volts.
I don’t have a schematic without it, its pretty hard to find what causes the problem.
I removed both BC640 transistors and swapped them, the problem remains.
Any suggestion
Thanks Allan
I have two Proton 520's with similar problems. My conclusion is that the poor-quality pots (volume) and pushbuttons (esp. "loudness") that are to blame. I haven't been able to find a schematic or even a manual either.
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