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John-Del[_2_] John-Del[_2_] is offline
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Default Harman Kardon 930 lost channel. Hoe to trouble shoot ?

On Friday, October 5, 2018 at 11:54:11 AM UTC-4, Steff wrote:
Well just lost a channel at my Harman Kardon 930 Vintage geek as I am I
want to keep my great Reciver and repair it..

What I done sofaar

Check Fuses ( They are OK)
Moving the speakers between the channels left-Right And A and B speaker
outlets.

With this info I understand that the left Channel is ALMOST dead turning
the balance to Left channel I can hear a faint OK sound. (Like the tiny
transistors trying their best before the end power transistors do their job.

My conclution.

1 Not enough power to the end transistors on the left channel.
2 Broken End Trasistors (two 2SC897 according to the scematics)
3 End of preamp broken on left channel.


Most likely End transistors..

Is my thinking OK or did I miss something ?

I am a beginner in HiFi electronics but have basic skills in electricity
as an electrician for 25 years and do know how to solder..



Normally, blown outputs (is this what you mean by "end"?) will open fuses or low value resistors.

You really need a meter to go farther. If you get one or have one, you can compare voltages and resistance from the good side to the bad. If the receiver has a pre-amp out and in (or tape monitor) arrangement, you can reverse those to see if the problem trades sides. If it uses metal U shaped jumpers, remove them and use RCA patch cords to cross swap.