I was checking the "idle current" on my beloved PM57 and a freak accident crashed the right amp - the scope ground lead popped loose and fell on a component in the circuit and instant smoke ! I was crushed. I love this amp. Its reproduction is superb. So, I rplaced a few parts and turned the amp on and more smoke ! What am I doing wrong ? I am a retired EE with many successful years of design and building of audio equipment - should I quietly give up ? Someone mentioned that the "new" Marantz amps are practically impossible to repair because most of the parts are "selected" when they are built - Thanks, Jack
Help ! Has anyone repaired a Marantz PM57 Amp ?
Oct 05, 2008
2 Replies
magic word "variac"
At least with a stereo amp you can DVM "diode" test between good and bad channels and remove obvious bad parts. Then gently power up , via a variac, no speakers, monitoring a few pairs of voltages to home in on some/all ? remaining obviously bad. Rebuild and power up again via variac , monitoring a few pairs of votages, etc, When all matches across , connect speakers, again powering up via variac , increasing volume gradually , still monitoring a few voltage pairs
-- Diverse Devices, Southampton, England electronic hints and repair briefs , schematics/manuals list on
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I have a PDF of the service manual for this model. It is about 2.75 meg in size, and I can e-mail it to you if you like, and assuming you can take the attachment.
(This is a good time to mention to the group that I an changing my e-mail address for the time being...)
You can e-mail me at:
mark snipped-for-privacy@labolgcbs.net
and reverse the domain to read "sbcglobal" and notice there is an underscore _ between my first and last name.
and I will send the manual.
Also, I have some experience repairing amps and might be able to help with technical advice.
Mark Z.
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