Members redrecord123 Posted July 2, 2014 Members Share Posted July 2, 2014 Hi all, first time on the forums here. I have a JCM2000 DSL100 head. Occasionally (and spontaneously) when I am playing, my volume will start to fade to silence and the glow in the V1 and V2 preamp tubes will be gone. After a few minutes both the glow and volume will return, or if I wiggle the tubes with my finger. I changed the pre amp tubes around and it ALWAYS happens to whatever tubes are in V1 and V2. Two of the tubes are stock (probably pretty old by now), and two of them are newer Groove tubes. The other issue is my effects loop. Whenever I plug my guitar into the return jack, i can get volume but none of my knobs work (which I'm assuming means I am successfully bypassing my pre amp, so that jack must work). However, when I plug anything into the "send" jack, i lose 98% of my volume. When i put a patch cable from the send to return jacks, my amp goes almost entirely silent. Can both of these problems be fixed with new pre amp tubes? Are the fx loops in these amps tube driven? If so, can having two different brands or old mixed with new pre amp tubes cause my fx loop to not get enough juice? I have sprayed every socket, tube, and jack with contact cleaner and nothing has changed. Link to comment Share on other sites More sharing options...
Members BC Audio Posted July 4, 2014 Members Share Posted July 4, 2014 V1 and V2 run on a DC heater supply, with the heaters in series. Most likely, the pins in one of the sockets are not making good contact - either it's dirty or has lost its grip. You can usually re-tension sockets from the top with a toothpick. I can't really help with the loop - something is obviously wrong with the Send, but the symptoms you describe don't ring any bells for me. But I don't think it has anything to do with the other issue. You can mix tube brands, no problem. Link to comment Share on other sites More sharing options...
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