Question about Harman Kardon Amplifiers & Preamps

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Wont power up.

Gentlemen, I am in a pickle,I have a problem that I hope you will be gracious enough to help with! I Purchased a Harman Kardon AVR75 on EBay,it did operate fairly normall when I received it,except for the audio cutting out at low levels. I decided to overhaul it due to the fact it had something spilled inside by the previous owner , the main transformer was rusted from it, Also it was loaded with dust. I discharged the whole system,desoldered & re-soldered the 4 main electrolytic caps.,removed and replaced the heat sink compound. I cleaned all the boards with contact cleaner . I just finished reassembling it. The pwr. button stays amber,the relay on the pwr. board clicks,and the pwr. button goes to red momentarily whenever any of the input buttons are pushed. I believe that since the whole system was de- energized the microprocessor has to be cleared or reset. Please help me to get the pwr. button Green again. God Bless W.G.D.

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My guess is in the desoldering-resoldering process...try to get back to every resoldered part you did. Be sure you returned the connectors to their proper terminals.
If you can trace the output circuit before the protection circuitry...try to get a near zero voltage. Any DC voltage appearing will trigger the protection - thus indicates red.
what else did I miss?...yeah! goodluck!

Posted on Sep 25, 2008

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