Need help to repair XM-N1004 SONY CAR Amplifier
The transistors Q210 ,Q211 very fast become hot with power connection with out any speaker connections or line input connection
I replaced them put the new ether fast heating Overheating
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1.Downward XM-N1004 service manual.
2.See P.9
3.Q101,201,301,401 4 transistors, tr, are for muting circuit only.
4.You will see 2 differential amps, then voltage amp stage.
5.Connecting to voltage amp is biasing circuit.
6.Biasing circuit controls the amount of quiescent current following through power amp stage. If quiescent current is too large, power transistors get very hot.
7.Power amp stage has driver amp and power amp. If driver amp is not good, power amp becomes very hot.
8.Check all components in bias circuit and power amp stage including driver amp.
9.If I were you, I could check ALL resistors first. How to check them on board? Buy a multimeter and check their resistances. Resistance must be small or be equal to marked value in service manual. Why? Defective resistor has its value becoming greater, never smaller!
10. If 9 is OK, replace ALL transistors in both biasing circuit Q206 & Q207and power amp driver stageQ208 & Q209.
11.(voltage amp,)V x (power amp,) I = Power.
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