ML No532 Amp Repair


So I’ve recently had a channel go out puff of smoke pop then go into protection mode. Now I have some questions about this for those who know. First the amp would pop in the bad channel on turn on, then it would pop in both channels when I would mute my preamp. Does this seem normal for that beast of an amp? Secondly, I’ve reached out to Harman about service and they gave me 3 service centers which are Pyramid Audio, Technetron Electronic Inc & United Audio. Which service center do you guys recommend since I’m in Indiana plus best in service? Any help/suggestions appreciated!



Those service centers have the ML schematics and parts. Pyramid's owner, I believe, worked for the old Mark Levinson brand. Any one would be a far better choice than finding a repair center on your own.

When an amp causes a popping sound it's DC current going to the speakers. If it's preceded by smoke it's most likely a shorted output transistor causing nearby components to burn. Tracking down the problem without a schematic is very difficult. 


Thank you! Good to know! Yeah I definitely want a shop that knows this amp inside and out. Not a cheap amp to "practice" tech skills on. I really like the fact that the owner of Pyramid worked previously for the brand. That helps a lot!


Over the decades, I have had a boatload of stuff fixed by Chris Lewis at Pyramid Audio, including Levinson.  Pyramid is a Levinson factory service center.  I can’t recommend Pyramid Audio highly enough.

I'm a long timer here at the Gon and reached out to Outpost4 b/c he came down to pick up a bunch of stuff from Pyramid. I now live in Austin so we hung out together and know each other from the boards. He's not a regular poster at the Gon but did me a favor and put up the preceding post, knowing that he had experience with Pyramid. 

Good luck! 

Bill Hart

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