3/2/2024 0 Comments Vox ac30cc2I never stopped to work out re-wiring the standby indicator light thru one of the two DPDT switch contacts so it's off when muting the amp by opening the cathode circuit of the power tubes. It was the 6/TB version that was known for mis-wiring the rectifier tube's output. It's a rectifier saver in an amp that seems to go through rectifier tubes more than most amps.I agree and have modified all of our rental AC30-6/TB amps in that fashion. You'll need to talk to the customer first, as it does render the standby indicator light useless. I'll often rewire the amp so that AC is always on the recifier and use the standby switch to interrupt cathode ground for the output tubes. Every time you go to play mode, the caps have to charge, which is harder on the rectifier. Make sure the red B+ wire is on pin 8 and not pin 2.Īnother thing I don't like about these amps is that standby works by effectively removing AC from the rectifier. B+ is taken off the wrong tube pin and actually goes through the filament. I've seen several of these where the rectifier tube is wired wrong. The HT fuse never died and do have the right value.Īny idea about what could cause intermittent shorts when power tubes are in place ? I am also a bit worried about repetitive attempt to reproduce the problem (with the limiter) that could damage the output transformer. This amp is cathode biased, I have checked voltage on the bias resistor which gave me an average of 25mA through power tubes at Idle, which seems good to me. Now I try to go through power cycles without power tubes but for now nothing happend, so it seems that the amp is intermittently drawing too much current but only with power tubes inserted. This happend also with all pre-amp tube removed. I have noticed that sometime the limiter get full bright with sound produced in the HP. This washer goes behind the faceplate on British style plastic nut and chrome nut jacks to provide proper spacing. Click on photo for larger view: WASHER, FOR BRITISH STYLE (CLIFF) JACKS. So changed the fuse again, put the limiter back and start to power cycle many time the amp. Found in the Vox AC15CC1, AC15CC1X, AC30CC1, AC30CC2, AC30CC2X, AC30CC2H. So I removed the limiter, re tested the amp and it blew the fuse again (with the buzz). So I have put a new set of EL84s (I also checked screen resistors) and played the amp with the limiter in place (150W bulb, partially lighting). I have replaced the fuse, removed all power tubes, started the beast with the limiter and checked HT. I have been given a VOX AC30CC2 that made a buzz followed by main fuse blow.
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