Help troubleshoot Harman Kardon AVR 1710 Amber light

[joystik]

Hello folks.

I have this HK AVR 1710 with amber light not powering up. Found corrosion on hdmi MCU board, cleaned as best as I could. Half of the front buttons didnt respond, including power button. I could do a processor reset with surround mode button, so that worked.

I powered it up a few times like this and sound and other functions seemed to work well. Still couldnt power on or off using buttons. So I downloaded the service manual from electrotanya (search avr 1710) and found the pins for the front buttons on the MCU. There was no signal reaching those pins and after 2 days I found 2 gaps on the copper traces which i fixed. Now the signal reaches the pins, however, there is still no response. And now, It wont reset.

I would really appreciate any input as to how to proceed as I have no experience in these digital receivers.

Thanks.

[tibimakai]

Re: Help troubleshoot Harman Kardon AVR 1710 Amber light

You should start cleaning the board, with an ultrasonic cleaner.

[joystik]

Re: Help troubleshoot Harman Kardon AVR 1710 Amber light

Hi. I dont own an ultrasonic, so I washed it with soap and toothbrush, rinsed with 99% Isopropyl and heated in reflow oven at 105C for 30 min.

The MCU is a STM32F205. Is there a way to tell if it is booting o working correctly?

[R_J]

Re: Help troubleshoot Harman Kardon AVR 1710 Amber light

I found 2 gaps on the copper traces which i fixed

If you found 2 bad traces I suspect there will be more, and due to double sided board, feedthru's might be corroded.

[joystik]

Re: Help troubleshoot Harman Kardon AVR 1710 Amber light

If you found 2 bad traces I suspect there will be more, and due to double sided board, feedthru's might be corroded.

Whats really troubling my mind is that those 2 gaps were on the same trace and under the green overlay. I had to uncover the copper every few mm to find them. How would that happen? Electrolysis?