5.1 receiver. Powers on normally and after a few seconds "OVERLOAD" blinks on display and doesn’t activate speaker output relays.
No power transistors shorted (2SB1560, 2SD2390 x5), output of each channel at 0V, no DC... Looks like a defective Protection detection.
PROTECTOR_IN line is at about -0,1V instead of expected 5,1V in normal state, but inputs of detector circuit are normal (-B from all channels on PROTECTOR lines and 0V from outputs). Q1302 (KTC3200) presents -B voltage on each leg, this is not normal according to schematics. Changed and fixed it!
It’s very important to screw ground tab EP301 when making tests with AMP board, because otherwise +B -B get ungrounded and this can damage amplifier.
I’ve found other issues with this same transistor in Denon receivers. I fixed a AVR-1311 and AVR-1910 with defective KTC3200 in amp section. I think it’s not a coincidence.
No power transistors shorted (2SB1560, 2SD2390 x5), output of each channel at 0V, no DC... Looks like a defective Protection detection.
PROTECTOR_IN line is at about -0,1V instead of expected 5,1V in normal state, but inputs of detector circuit are normal (-B from all channels on PROTECTOR lines and 0V from outputs). Q1302 (KTC3200) presents -B voltage on each leg, this is not normal according to schematics. Changed and fixed it!
It’s very important to screw ground tab EP301 when making tests with AMP board, because otherwise +B -B get ungrounded and this can damage amplifier.
I’ve found other issues with this same transistor in Denon receivers. I fixed a AVR-1311 and AVR-1910 with defective KTC3200 in amp section. I think it’s not a coincidence.
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