Nightmarechevy Posted December 17, 2021 Share Posted December 17, 2021 Looking at a Blues Custom 30 for a friend. His complaint was that it wouldnt power on. I checked all internal fuses and HT fuse (good) but the mains was blown. Replaced the mains fuse and it powered on normally and went off standby normally but had no sound. I pulled the tubes to inspect and the phase inverter tube had lost vacuum (white flaky getter). I ordered a 12at7 after reading up on phase inverter tubes this amp and after replacing it the sound returned and everything worked great but no reverb. I tried another 12ax7 tube I had in V3 and V5 but they didnt help. A few hours later I tried the amp again and noticed a blue spark when going off standby in the V8 rectifier tube. I plugged it into a dim bulb tester and intermittently going off of standby causes a brighter bulb while other times it acts normally. I am new to tube amps so I checked the reverb transformer looking for a possible short and the secondary seems low on a resistance check (1.2 ohms) but I am unsure of what a normal resistance would be. Does this sound like a shorted transformer secondary or has anyone else had a similar issue? Quote Link to comment Share on other sites More sharing options...
Andyroid Posted August 4, 2022 Share Posted August 4, 2022 The problem with the rectifier tube is caused by the power transformer not being specced correctly, its DC resistance is too low. But don't worry, simply stop using the Standby switch. It is perfectly safe to leave it in Play. On amps like this, the Standby switch is only there because guitarists tend to think that all tube amps need them, they don't. There is nothing about the BC30 that demands a Standby switch. I would suggest only using 12AX7 in every position in this amp, I've tried all sorts and 12AX7 always came out best. 1.2ohms for the reverb TX secondary sounds right. Maybe the tank is plugged in backwards? Quote Link to comment Share on other sites More sharing options...
wildschwein Posted August 9, 2022 Share Posted August 9, 2022 (edited) Yes I owned one of these years ago and the advice at the time was to not use the standby switch. I, in fact blew two rectifier valves before I discovered this. The amp naturally heats up to operating temeprature if you just turn it on. It takes 15 to 20 seconds or so for the sound to come on. I also remember the amp chewing up a few 12ax7s in the reverb slots. I would recomend buying from a tube seller who has tested their tubes and offer a warrantry on faulty ones like Eurotubes for example. All the preamp slots do call for 12ax7s so go with those. Edited August 9, 2022 by wildschwein Quote Link to comment Share on other sites More sharing options...
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