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Old 05-16-2019, 05:57 PM   #21
R_J
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Default Re: Harman Kardon AVR 270

Yes, I scrolled up too far to the Center channel
If R723/725 are open transistor could be bad, also check the base resistors, R647/652, then work back checking the driver transistors and resistors. comparing same components to a working channel is helpfull sometimes
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Old 05-16-2019, 07:08 PM   #22
playman
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Default Re: Harman Kardon AVR 270

My DCA55 says that there is a short between Collector and Emitter on Q652 trans.
The other two seem to be ok.
Will be testing rest of the stuff tomorrow.
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Old 05-17-2019, 06:54 PM   #23
playman
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Default Re: Harman Kardon AVR 270

Just finished testing all the components in that channel.
Nothing out of the ordinary as I could notice, except for one Diode.
D582 measured 400kΩ and rising when positive probe was on cathode, other Diodes
did not do that, trans Q652 and the two resistors R723 and R725 are not installed.
Q882 and Q871 seemed ok.
I did not check the To-92 Transistors though.
Capacitors measured fine with the ESR meter, did not check the ceramic ones though.
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Old 05-17-2019, 07:39 PM   #24
R_J
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Default Re: Harman Kardon AVR 270

You could lift one end of D582 to check it, Check the transistors like Q562, Q502, maybe they have some leakage.

Last edited by R_J; 05-17-2019 at 07:43 PM..
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Old Yesterday, 10:25 AM   #25
playman
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Default Re: Harman Kardon AVR 270

Quote:
Originally Posted by R_J View Post
You could lift one end of D582 to check it, Check the transistors like Q562, Q502, maybe they have some leakage.
D582 Looks ok.
Q562, Q502 looked ok also, I also checked the other remaining 6 and they also looked ok.

So I guess there is nothing left but to order the Q652 trans and the 0.47Ω resistors, plug them in and turn on the amp?
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