• WARNING: Tube/Valve amplifiers use potentially LETHAL HIGH VOLTAGES.
    Building, troubleshooting and testing of these amplifiers should only be
    performed by someone who is thoroughly familiar with
    the safety precautions around high voltages.

Lumley M250 Woes

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I have a pair of M250s that have died. I will go into detail on what exactly happened if anyone is interested, it is very bizzare. I got these amps from Jonathan Valin with no documentation whatsoever. These were sent to him for review, and I guess he threw all that out, or was never sent any (these amps are not the ones re-sold with the Reference label). Anyway they just quit working yesterday. Both at the same time, which makes no sense. I have tried all the basic troubleshooting, and have found nothing obvious. They just won't turn on any more. Not even the warm-up stage.

Any help would be greatly appreciated, I miss them already.

Thanks in advance,

Scott
 
Can't seem to find schematics anywhere on the web for these amps, only pictures - they look quite impressive!

Have you checked for continuity on all the windings on the mains transformer? As other posters imply it sounds like a power supply problem.
 
After tracing the electrical path from both switches discovered that two resistors cooked on them. Now here is were it gets really strange. The fuses did not blow on either amp, I only turned one amp on yet both amps went south. To make it even more bizzare, they were on either side of the room plugged into two different outlets and no other equipment was affected. This whole occurence has me baffled.

I flipped the warmer switch, once the tubes started to glow I flipped the B+ switch. Sparks flew in one of the tubes, I shut it down. All within about 2-3 seconds. Again, I must mention the other amp was turned completely off whole time, and yet it suffered the exact same resistor damage, all the while the rest of the equipment plugged into the same outlets suffered nothing.

Anyway, thanks for the replies, and if anyone finds a schematic, I'll buy it 😉
 
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