Bugera 333xl 212 combo problem

[Enzo]

Well, you can check for shorted parts with the power off, so no fuses at risk there.

[Stormrider]

OK, got the current limiter together and it works like a charm. I checked D16-19 with my Fluke which has a built in diode checker. All 4 of them check out, conduct current one way and don't let any through when hooked up backwards. Both of the caps seem to be working, they will beep for just a second when I do a continuity check and then block the DC.

I then unhooked the power/standby board, tossed a new fuse in, plugged the amp into the current limiter, and turned it on. The 100w bulb fired right up, indicating a short, and saved the fuse.

At this point I'm at a loss. I could just flat out replace the diodes, and the caps, but I don't think they are the problem at this point.

One other note, there's a humming sound coming through the speakers, and I had ALL of the tubes removed. It's not very loud, but it is there.

I'll check back here tomorrow, after I do a bit of tracing on the PCB, and see if I can find a problem component.

Thanks for all the help so far!

-Josh

[TrajanGregory]

Hey There Enzo,

I've been reading through this thread because I have the same problem - Mains fuse blows at power switch to ON.

However, I saw a miscommunication between this response and the previous post. The previous post indicated that he removed ALL connections to the power X-former, and that the fuse did not blow ... But he missed a step > Remove the secondary outputs, but keep the primary side connected, to prove isolation within the primary circuit ... that was apparently missed ... I will start a new thread with my problem ... same exact issue - blows the main fuse, with unit in standby, and with all tubes removed ... thankfully, I have about 28 fuses remaining ...

[Enzo]

Look up, make, and use: a light bulb limiter. Don't throw fuses at it.

[Cytagasm]

Hi, I know this thread has had no activity for a while, but I've been following it desperately trying to diagnose my own Bugera 333xl which has been blowing fuses for a number of years and I'm finally able to get round to making progress on it. So if anyone (Enzo:P) can respond I'd be hugely grateful.

I've been following this thread and I got to the point where I've been lifting internal fuses off the board. My amp does not blow when F1 is lifted but will blow fuses when F1 is on the board. Enzo said that this indicates the high voltage supply has issues. Where would you suggest I go from this point in trying to identify the problem?

Thanks in advance

[52 Bill]

Welcome to the place.

My amp does not blow when F1 is lifted but will blow fuses when F1 is on the board. Enzo said that this indicates the high voltage supply has issues. Where would you suggest I go from this point in trying to identify the problem?

The first place to start is to create a new thread so we can help you and your problem without having the baggage of the older threads.

As Enzo pointed out, the F1 fuse is for the high voltage power supply. So there may be a problem in the power supply itself or with one of the circuits that it is powering. If you have a big supply of 2 amp fuses, remove all of the power tubes and try the amp again with a new F1 fuse in position.

If you have the skills, build yourself a light bulb limiter and save yourself the cost of fuses and other possible components. What sorts of test equipment do you have access to?

[Cytagasm]

Thank you for the response 52 Bill.

At your suggestion I have created a new thread here Bugera 333xl (non-Infinium) popping fuses.