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LUXMAN L-100 ISSUE

Subchannel

Subchannel

Active Member
I have a Luxman L-100 in near mint condition, and the former owner recapped the PSU. It plays as it should the first hour or two, but then the right channel disapears. When turning up the volume one can hear very low and thin sound. Anyone here familiar with this issue/ amp? Thank you in advance!
 
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Also clean the tape monitor and if it has one, the tone defeat switch / button.

When it cuts out, wiggle the toggle switches. If it comes back, it shows they really need to be cleaned.
 
The fact it takes an hour leads me to think cold solder joint, or *maybe* a transistor that's headed for the exit. It's not controls or relay if it works perfectly until then.
 
Above by @ivandezande... inspect for aged solder joints (less shiney than the others) on the driver transistors for one, check outputs too, lux seems to have smallish solder pads and with heating and cooling of the transistors, these solder joints age faster than the rest of the board. Good chance the pre owner didn't inspect further than the cap job.
 
Thanks for all replies. It´s not a mechanical problem, alle pot´s and switches are thouroughly cleaned and tested. The sound "dies" out after a ehile. My thought also was to resolder the output transistors. I know the recap is done by a non professional, but it looks like a ok job.
 
Hm, no difference. Have taken the amp apart, removed output PCB´s and resoldered all transistors and some joints. Also tested all switches/ pots again just to be shure, no problem there. The amp plays as it should for 1-2 hours and then dies out. It´s not completely dead, a very low thin sound remains. Further inspection shows that the former owner did not recap all, just a few small electrolytics in the PSU. I suspect that a recap of the whole amp would fix the problem, as I´ve experienced the same problem on other amp´s. Any thoughts?
 
I guess you have to play it as you see it. No service manual. If it has a relay give that a tap.. maybe caps in that circuit? meter check to see it's getting enough juice.
 
Thanks for the tip Binkman, that sounds like a plan. I will also disconnect the pre/power link to check which part is failing, but my guess is the power amp.
 
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