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Old 11-21-2020, 05:55 PM   #1
Gary Indiana
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Join Date: Sep 2011
Posts: 3
Default Harman Kardon AVR 125 display scrolling and blinking and no sound

The unit was made in 2002. The display keeps scrolling and flashing, and when doing it there is no audio at all on speaker or headphone outputs. You can read the display between the strobe effects and see the volume change on the display when you turn the knob but no sound. I did the full reset by pressing the tone mode button, but no change.

The above problem is intermittent: after the unit is left unplugged for a while (a day), it turns on and works normally, without blinking display and works great with no interruption. Once I turn it OFF and then ON, the same blinking problem starts again.

So far, I tried to find cold solder spots and resoldered all questionable points on the boards, and removed some old brown factory goo spots from the boards.

I found one other post from 2014 on Fixya with the same exact problem but no solution (even though it is marked as SOLVED).

I don't have a working scope right now. I have Fluke 87 V and service manual for this unit.

Thanks in advance for any suggestions.
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Old 11-23-2020, 09:46 PM   #2
Gary Indiana
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Join Date: Sep 2011
Posts: 3
Default Re: Harman Kardon AVR 125 display scrolling and blinking and no sound

I got response from "level 2" tech support at HK,
Thank you for contacting Harman Audio. This is DJ one of the audio specialists. I do understand that having issues with your AVR can make the listening experience less desirable but don't worry, I am here to help.

In the rare case where the unitís operation or the displays seem abnormal, the cause may involve the erratic operation of the systemís memory or microprocessor. To correct this problem, first unplug the unit from the AC wall outlet and wait at least three minutes. After the pause, reconnect the AC power cord and check the unitís operation.

If the system still malfunctions, a system ďresetĒ may clear the problem.

Blah, blah ...

If these steps do not solve the problem, we recommend that you consult an authorized Harman Kardon service center. Listed below are the service centers near your area.
Pretty useless. I will add a few extra caps in power supply traces near chips that may be sensitive to noisy supply voltages. Will post results later.

The machine is basic, but I would love to get it up and running for a few more decades.
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