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After over a decade of reliable performance my beloved EE M520 integrated has become possessed. The amp still magically works sometimes, but mostly not. Powers up and all tubes heat-including the new rectifier tubes I just put in-but no signal. Sometimes pentode is indicated, other times ultralinear. The knob light stays solid, no flashing for warm up, no ability to select mode. AND, most recently, sometimes the volume knob turns all the way clockwise on its own!
After a lot of fruitless searching I finally found a tech in this area (northeast PA) who can fix it, and will, IF and only if I can get him the Service Literature. I've pounded the internet to no avail. Is there any chance any of you have or can source that literature, or tell me where I can get it? I have already rudely contacted the now retired Bill of the now defunct US Distributor Morning Star Audio and hopefully he'll have it. My Internet gumshoe work had so far yielded zip.
Thank you folks
Never stop learning. Then forgetting. Then learning again. Repeat.
Follow Ups:
Move your question over to the Tubes DIY section and you will greatly improve your chances of getting a useful answer.
The M520 is the classic Mullard El34 circuit and the basic schematic is simple. Worst case, a competent tech should be able to get it working again at least with manual functions. In other words, give you a manual volume pot and switches for triode/pentode/ultra linear.
I wish they still sold the M520. I would buy one.
Good luck.
Thanks for the reply and the advice. I'll move on over to Tubes/DIY.
Also, in my online quest for info/help I've come across a few units for sale on Audiogon/eBay etc, you could probably run one down.
Never stop learning. Then forgetting. Then learning again. Repeat.
Another reason I will NEVER buy a new component without all the schematics attached.
I remember seeing very early Kenwood (or was it Sony?) in maybe '71 or '72 that had a big section of the manual that came with the piece devoted to schematic....This when I was going to school in Tampa.
That will be one of my 'test' questions should I ever buy a new component.....
I asked for a schematic from HSU Research and got the Big Blow Off and some nonsense about proprietary. Are you joking? What new science did they invent for the amplifier? Sub is 10 years old if it's a day. And should it fail? JUNK.....
Too much is never enough
The schematic doesn't always resolve the issue. I recently tossed two good quality tuners into the trash because a proprietary LSI in each one was no longer available.
Proprietary is also a valid problem.....
/such parts are now part of lots of gear. I'd personally be careful. I don't see any reason to buy an amp with such a part. Tuners / HT / pre-Pro are another matter.
Me? Tempted to buy a pair of the VTA M125 power amp KITS and have at. No proorietary electrnics in either.
Too much is never enough
Thanks for responding. LSI...- like, circuit breakers? Or microchips that control switching/LEDs? Yeah, Eastern Electronics no longer exists, so I have to be prepared for finding out whatever I need is long out of production. The former distributor is reaching out to the amp's designer and if he's successful in doing so I imagine the truth—good or ill—will be known then.
Never stop learning. Then forgetting. Then learning again. Repeat.
...-could be effecting the lights/indicators on the faceplate of an amp, including the motorized volume knob which is only operated by the remote?
To clarify, the amp gets power, all tubes glow, but the warmup process (flashing light on volume knob for 90 second wait period) doesn't happen, indicator lights for pentode (red) or ultralinear (amber) light randomly, and mode select does not function at all.
Is this an intermittent short? Dust in the pots? A failed cap? Surely no tube is responsible for switching functions?
Any insights and/or wild guesses much appreciated.
Never stop learning. Then forgetting. Then learning again. Repeat.
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