Harman Kardon AVR20 ii


This amp was on standby and not powering up. Upon checking Q201(relay drive) was open. After replacing the transistor, the amp turned on as normal. Some of the input source (tuner,tape1) were not functioning. Upon inspecting the front board, I realise that the solder joints were bad, so I took out the front board and resoldered the whole board. After reassembling, the amp does not turn on. It is on standby again. There is 5V present on pin34(Vdd) of the cmos microproccesor, but no voltage on pin80(standy relay). No voltage on pin80 means no base voltage for Q201, the relay drive. I am not familiar with CPUs, and wonder what could have gone wrong. I have checked Q201 and all other components on the power supply board, they are OK. Could the CPU itself be the problem. Pls assist.


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