Author Topic: Help on documentation for Mark Levinson 331 amp.  (Read 2842 times)

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Offline CHexclaim

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Help on documentation for Mark Levinson 331 amp.
« on: September 17, 2016, 04:44:19 pm »
Hello everyone,

I received for repair an old Mark Levinson number 331 amplifier. As I told the owner, it is very difficult to do a proper repair without the service manual and/or schematic.

I've searched online and had no success but maybe I am not looking in the right places. The owner will try to find it too, but, I doubt it.

Can anybody help with these?

Thank you!!

Charlie.
 

Offline singapol

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Re: Help on documentation for Mark Levinson 331 amp.
« Reply #1 on: September 18, 2016, 05:26:00 am »
If you are an experienced audio power amp tech you would know Mark Levinson does not give out schematics or service manuals even if you ask their official repair centers in US. What's online are much older models of which ML331 is also  over 20 yrs, old. Any good/skillful tech can repair such amps without schematic or documentation. A search online will show that ML300 series are prone to power filter electrolytic capacitor failures. Anyway they are due for replacements which is not cheap but only 2 x 50 000 uf. and another smaller pair. Do be careful of big caps! Also because ML331 is operating in class A bias so it's hot so heat will take it's toll on output transistors. There is a difference between restoration and repair as a repair
tech I'm sure most would just fix it and throw it back to customer,so it's your choice to do a proper job or risk customer returning back to you for another repair. Is there pride in your workmanship?

The closest to a repair manual is a link below although  the schematics are not very clear..someone asked for
details but not sure if he got them from blogger.

ML332
http://my-mlnoxxx.blogspot.sg/
 

Offline voltz

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Re: Help on documentation for Mark Levinson 331 amp.
« Reply #2 on: September 18, 2016, 06:39:41 am »
This chap did some work on the ML-331
http://playagainaudio.blogspot.co.uk/2013/06/restoring-mark-levinson-no-331-from.html

See the posts at the bottom, someone out there has the service manual.

Just keep searching. The manual does exist.

Cap failure seems common in the 300 series. These guys found replacements:
http://audiokarma.org/forums/index.php?threads/mark-levinson-331-cap-failure.582299/
« Last Edit: September 18, 2016, 07:20:17 am by voltz »
 

Offline CHexclaim

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Re: Help on documentation for Mark Levinson 331 amp.
« Reply #3 on: September 18, 2016, 02:21:48 pm »
Thank you for the help!

I will check all links now. I haven't opened the unit yet and I was told that the unit went through another technician before that couldn't fix it  :( That is not a very good sign.

The idea is to do a good repair, not just to make it "work".

Thanks again! Charlie.
 


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