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OR15 strange volume behaviour
Posted: Sat Feb 03, 2018 7:55 am
by perbra
After working working just fine some 2 years my OR15 have a strange behaviour when turning it on. It is just like both volume pots are bypassed and goes on full volume. And without touching it also produce oracles and noise. If you touch the input jack it is like switching the volume pots on and off. But if you leave the amp on for 30 minutes it sound wonderful. I have had it to a pro tech, but he did not find anything wrong with it. However the problem have increased. Have tried to swap tubes. I have opened it and try to find a poor connection or something without success. Any suggestions.
regards
Per
Re: OR15 strange volume behaviour
Posted: Tue Feb 06, 2018 7:57 pm
by Les Paul Lover
If you have changed the valves, that's the only thing you can do yourself.
You will need to find another tech who can diagnose the issue.
It could be a number things. Difficult to give more advice from afar.
Re: OR15 strange volume behaviour
Posted: Wed Feb 07, 2018 1:00 pm
by PBA
If your tech didn't find anything wrong, you might need to find a new tech...
If you trust your tech it might be worthwhile arranging to be there when he checks it.
Valves are ALWAYS a highly cause and after two years it's certainly worth replacing the power valves (pre-amp valves - possibly but start with Power valves). You can do it yourself. You need a matched pair of EL84 valves. JJ were original equipment on my OR15. JJ or EHX should be fine and not too expensive. Preamp valves are 12AX7 and one 12AY7. Start with ONE 12AX7 and try it in all the positions one at a time. If the amp gets better, it is likely that only the one valve was failing.
Loud volume and crackles might indicate something other than valves though. Clean all the potentiometers and jack sockets. That might help too.