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Pioneer Receiver Repair

Like Pete said PWR supply voltages can directly affect the operation of the Relay. So check all the voltages (both AC and DC) on the power supply using the schematic, and also the voltages on the Protection board (AWM-025) as the RELAY is directly connected to the Protection board from pin 10 for power. Pin 11 is the pwr input to the protection board, feeding off of pin 14 on the Power supply board (AWR-057). Q7 and C6 set the correct timing when the relay closes for the 1st time upon power up. A weak Q7, IIRC can cause drop out's and relay chattering due to flyback voltage when the power goes off. Which is why a 1n4004 diode is installed between Pins 9 and 10 (Cathode to pin 10) to block the flyback voltage. I think this is your problem. AFTER Determining and repairing circuits for correct voltage, and it still chatters or drops out, replace the 2sc1384 with a 512-KSC2690AYS and C6 with a 100uf 25v 647-UPW1E101MED cap. You might as well rebuild the whole board while you are at it.

AWM025 PROT
AWM025 c1 0.22 10 cssa 598-DSF050J224
AWM025 c2 0.22 10 cssa 598-DSF050J224
AWM025 c3 330 6 cea 647-upw1c331mpd
AWM025 c4 330 6 cea 647-upw1c331mpd
AWM025 c5 4.7 25 cea 647-UPW1H4R7MDD
AWM025 c6 100 16 cea 647-UPW1E101MED
AWM025 q1 2sc869 512-KSC1845FTA
AWM025 q2 2sc869 512-KSC1845FTA
AWM025 q3 2sc945 only if bad 512-KSC1845FTA
AWM025 q4 2sc945 only if bad 512-KSC1845FTA
AWM025 q5 2sa733 only if bad 512-KSA992FBU
AWM025 q6 2sc945 512-KSC2383YTA
AWM025 q7 2sc1384 512-KSC2690AYS
chassis prot relay 653-LY4F-DC24
Flyback Diode. 512-1n4004
 
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