Melos 400 restoration project - need help (unaltered reference needed) - diyAudio
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Old 21st March 2011, 05:24 PM   #1
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Default Melos 400 restoration project - need help (unaltered reference needed)

Hi everyone - haven't been here for a while... but now, I need some help from the pros here.

I'm working with restoring two Melos 400 monoblocks for a friend that bought them for a very low price. The catch was that they were non-functional. Above the normal restoration procedure (replacing electrolytics, power resistors, sockets and obvious broken parts), I have to work out the gremlins in the system. It would be fine if the amps haven't been altered by the previous owner. All over the thing, I can see changed resistors, added caps, replaced MOSFETs and cut traces... even wrong type of input stage tubes was installed so I suspect the input stage have been altered (additional parts seems to have been added around the tube socket).

The problem is that I have no reference to follow, so I don't know what changes are done by the user and what are done by Melos (if they even did these kind of changes). And without any schematics, it is really a guessing game. So, if there are someone out there with the same type of amplifiers that are kept in factory delivered configuration - I like to kindly ask for some good pictures of the PCB, both component- and solder side. That will do as a reference to see what should be there and what not. Maybe it even could help me to reverse engineer the thing...

Thanks in advance...
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Old 19th April 2011, 12:19 AM   #2
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I have a schematic i can email to you. you can email me at
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Old 28th December 2011, 06:56 PM   #3
barda is offline barda  Greece
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Originally Posted by amacrine View Post
I have a schematic i can email to you. you can email me at
hello i have some problems too with my melos 402 gold monoblocks amps and my melos 333 plus pre, can you send me the schematic if is that possible and to me?
Thank you very much in advance
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Old 17th September 2013, 06:49 AM   #4
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Default Melos 400

Originally Posted by amacrine View Post
I have a schematic i can email to you. you can email me at
Hi, I have been searching for the schematics of the Melos 400. I have a pair that is not working. It looks like no modification has been done. Could you please share with me your copy of the schematics. I would appreciate it very much.
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Old 21st April 2014, 03:57 PM   #5
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Location: Perth, Western Australia
Default M 400

Hello, I have a pair of M 400's, one of which has stopped working (no problems in 20 years). If you still have schematics I would very much appreciate a copy. I also have the three-chassis Plus series MA 333's. Do you know where I might get a copy of their schematics as well? These beautiful amplifiers are practically unknown here in Perth (Western Australia), and nobody is willing to touch them without documentation
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Old 9th June 2014, 11:15 AM   #6
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Location: Perth, Western Australia
Default M 400 Working Again

Received with thanks some schematics from amacrine. I have a few others now, one of which is attached. I found the two 22 ohm resistors on the slow-turn-on board had blown. I assembled a pair of wire wound resistors (10 and 12 ohm, 25 watt) on a metal bracket, and fixed it to the chassis at the power transformer's bolt. I then wired the resistors across the blown ones on the circuit board. (To remove the circuit board for a neater repair was too daunting a task for me.)
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