HELP....NEED Mcintosh schematic.. - diyAudio
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Old 11th February 2012, 05:28 PM   #1
diyAudio Member
Join Date: Feb 2012
Default HELP....NEED Mcintosh schematic..

Hello...i'm very need help...i need a repair schematic for my mcintosh car amp mc-425...the problem is the amp can power up, but the power guard bulb stay on and no sound at all...before that amp broken, it always make a high pitch sound a couple of days...and now is broken...any help is expected....thank you...

best regards
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Old 11th February 2012, 05:46 PM   #2
diyAudio Member
Join Date: Dec 2005
Location: Northern California
Here is a link to a mac 431 schematic perhaps it can be helpful...

URGENT NEED: McIntosh MC431 service manual - - Scientific Car Audio - Truth in Sound Quality

Its in pages of the post but it is readable...hope this helps some...
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Old 11th February 2012, 06:54 PM   #3
diyAudio Member
Join Date: Feb 2012
hello, 1more...thank you for your assist...but it will be better if there is a mc 425 service schematic cause both amp is different...

mr 1more...i think you are expert in mc..i had read your post..can you help guiding me to repair this amp? thank you in advance...
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Old 11th February 2012, 09:08 PM   #4
diyAudio Member
Join Date: Dec 2005
Location: Northern California
Oh I am no expert, but I do own a couple of them, and all of them came to me non-operational.

I don't have any info on the 425 model but I am sure they are all similar by design. The problems I found them to have revolved around leaking caps in the power supply, bad op-amps in the front end, bad solder joints on all the power devices, Blown mosfets in the power supply, and of course the problematic Power guard circuitry which I am still trying to figure out myself.

Would it be possible for you to post some pictures of the inside of your Mac? I will try to be of some help...
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Old 12th February 2012, 05:07 AM   #5
jc2 is offline jc2
diyAudio Member
Join Date: Dec 2001
Location: Atlanta, Georgia
I don't have the schematic for the 425, but McIntosh service department will have one, and they are pretty reasonable cost to get them.
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Old 12th February 2012, 05:04 PM   #6
diyAudio Member
Join Date: Feb 2012
thk you 1more and jc for the fast reply....tommorow i will take the picture and post it in here...and i will try to contact mc intosh to buy the mc 425 schematic....hope without the schematic, i can fixed that amp....
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