The windings in the transformer could short to open and then not trip again after a reset. If you have a bad power transformer you probably will be blowing fuses or circuit breakers on the AC line. So the cap may die but the transformer will be ok. but modern amps are usually protected from that exact scenario. it is possible it took out a power transformer. If a power capacitor went down in a blaze of flaming glory. The most likely candidate for a completely "dead" amp is a power supply filter capacitor. :-) Check that fuse if the amp is totally silent. it didn't do it by itself -) and so I imagine we would have been entertained with stories about how much fun that was. Is it totally quiet? The fuse between the amp and speaker will trip if the speaker connections are shorted. it may switch out the input signal but you can check for self/system noise in the amp. One bad preamp tube will not usually result in complete silence. One bad power tube will not result in silence. and these tubes were also designed to be run 24/7 in stationary radio sets.
VOX AC30CC2 SWITCH REPLACEMENT PORTABLE
These tubes were designed to be banged around in portable radio sets. Honestly, that is sort of like saying that burning a light bulb continuously will make it too hot. or at least pull the chassis and look for burnt out parts before placing a fresh tube in. so you'll want to know what really happened. If it's something else that killed one of your tubes. internal sparking, red glowing plates melting into Salvador Dali shapes, fire, smoldering black soot on the sockets. but if it was a bad tube the tube will probably have seemed bad. where as a burned out resistor, bad tube, or dead capacitor is common. The point I am trying to make is that you probably have some routine part failure. although the original Vox line did have a reputation for running hot and overheating, the reputation is largely attributed to lack of ventilation. and leaving a amp on for a few days is not typically something that will hurt it. With the amp is standby the amp shouldn't be as hot as when it is not in standby mode. "Standby" implies that the heaters in the tubes were being heated but that the plates and grids did not have high voltage on them. It's going to be hard for any of us to comment without having some idea of the symptoms you are experiencing. You haven't actually described the problem. He can play his Blues Deville through the holiday but if we can get the VOX going for the shows it would help immensely. Did I hear that right or do I have that backwards? I've never played with the internals on his VOX and I have a Fender Twin, so I wanted to get some advice from any geniuses here who may have some troubleshooting procedure we can go through to solve where the issue lies and any temp fixes we can do during the holidays. But if the fuse blew with new tubes then it would be a tube problem. He also mentioned if I put in new tubes and the fuse didn't blow then it would confirm the transformer. So, my question for you guys is:Ĭan the tubes be overheated? Is it possible this is an easy fix or unlikely? I talked to one guy in LA who can service it when I get back and he said replacing the tubes isn't going to matter at this point. We could have blown the transformer, but I thought I would try to replace the tubes first. We're not near any dealers at the moment to drag it in, so trying to see who here can help us diagnose the problem. We're trying to repair his VOX AC 30 which was left on for a couple of days on Standby by mistake. Any comments would be appreciated.Overheated Vox AC30 CC2 late 90s/early 2000s edition - repair help Therefore if the standby light flashes, is this a sign the GZ34 rectifier is on its way out. 80% you can't see the standby pulse and the voltage on the GZ34 cathode has dropped to 50v p-p.
100v p-p on the scope and this seems to be sufficient to turn the Q104 on/off and hence the standby light.Īlthough the above internet posts suggest this is normal, I had not seen this before so I replaced the GZ34 and now, unless the tremolo depth is able approx. Measuring the voltage on the GZ34 cathode (amp at idle ) showed a voltage swing of approx.
VOX AC30CC2 SWITCH REPLACEMENT MANUAL
I noticed the addition of two 200 ohm, 22w resistor in parallel and wired in series with the standby switch (this looks like a factory mod) but not on the VOX service manual schematic.
Although a number of posts on the internet suggest this is normal due to the way the tremolo voltage is delivered to the EL84 grids, I decided to investigate further. Just been fixing an AC30CC1 for our lead guitarist who reported the standby light pulsing at the same rate as the tremolo controls.
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