Bugera 333 212 combo, very low output

[nosaj]

A typical tube tester isn't a 100% accurate method of testing tubes. If the tester says it's bad- it's bad. If the tester says it's good, it might still be bad. Substitution is the best method. I'd also wonder if the shop knew what they were doing and how they tested them. I'm not saying they didn't. I don't know who they are. But, as an example, there was a shop here in town that was testing tubes for customers. They didn't even know that you had to test both elements of a preamp tube.

Maybe Dual triode escaped them

[nosaj]

Maybe Dual triode escaped them

Or a Fool and his money are soon parted.

[bwheat]

A typical tube tester isn't a 100% accurate method of testing tubes. If the tester says it's bad- it's bad. If the tester says it's good, it might still be bad. Substitution is the best method. I'd also wonder if the shop knew what they were doing and how they tested them. I'm not saying they didn't. I don't know who they are. But, as an example, there was a shop here in town that was testing tubes for customers. They didn't even know that you had to test both elements of a preamp tube.

That is kind of what I was thinking, maybe they only tested one side of the tube. It is pretty obvious that at least one isn't working properly or else it would work the same when the tubes were swapped around.

[Enzo]

Tube testers do not put real world conditions on a tube. As was said above, a tester can point out BAD tubes, but it can't really tell you a tube is good. Both sides may have tested OK on their machine.

[bwheat]

Tube testers do not put real world conditions on a tube. As was said above, a tester can point out BAD tubes, but it can't really tell you a tube is good. Both sides may have tested OK on their machine.

Is there a good way to actually test that the tube is doing what it is supposed to when it is in the amp. I have thought about buying some cheap Russian reflector brand tubes just to test this thing out and keep them as spares.

[nosaj]

Is there a good way to actually test that the tube is doing what it is supposed to when it is in the amp. I have thought about buying some cheap Russian reflector brand tubes just to test this thing out and keep them as spares.

DMM Checking the voltages on the pins will tell you how the tube is performing.
Do you have one? Even the cheap Harbor freight ones will work. My problems has always been when the 9v battery gets low readings go wonky.

nosaj
nosaj

[Enzo]

Sure, by the performance. A tube is noisy or not, it hums or not, it amplifies or not, etc.

[bwheat]

DMM Checking the voltages on the pins will tell you how the tube is performing.
Do you have one? Even the cheap Harbor freight ones will work. My problems has always been when the 9v battery gets low readings go wonky.

nosaj
nosaj

I have a nice one, I will get the tubes back in and take some measurements. I have a few of the harbor freight ones as well, they work fine, but the leads always break on them. I am usually upside down under the dash of a car with them so I am kind of hard on them.

[bwheat]

Finally got a little extra time and cash to work on this thing. I replaced the preamp tubes, and it is a tad bit louder, but still about the same as before. Still has a little bit of a hum also. I will make a video here in a bit as to what it sounds like.

[bwheat]

Would is work to test the pre amp and power amp to run a cable from the line out or head phone jack on a separate amp to the effects return to test the power and then run the cable from the effects loop out unto the front of the other amp to test the pre amp? Also when the effects loop is kicked on should there still be signal going thru to the speaker without anything hooked to the effects loop. I get a very low sound that still goes thru. Also a loud popping noise thru the speaker and then more hum when it is switched on. I recorded a clip of this, but my iPad video wouldn't load on here for some reason.

[Enzo]

Yes, you can apply a signal to the FX return from elsewhere. Hell you can even just plug the guitar in there. And yes, you can send the preamp out from the FX send to some other amp.

[bwheat]

Yes, you can apply a signal to the FX return from elsewhere. Hell you can even just plug the guitar in there. And yes, you can send the preamp out from the FX send to some other amp.

I have tried the guitar plugged into it, and I just get some light popping noise when you strum it. Trying to find my spare cable to hook up to another amp. Is it normal to get sound when the effects loop is on and the guitar plugged in the front? Seems as though nothing should make it thru as the preamp is not hooked to the power amp when it is switched on, is this correct?

[g1]

It depends if it is a series loop, or parallel.

[bwheat]

I finally located my extra guitar cord today and tried hooking the other amp up. When I do effects loop out to the input on the other amp I get the same thing, a humming sound and very low volume on both amps at the same time. When I hooked the line out from the other amp into the effects return I get full power, very loud volume, but it is very distorted even on the clean channel. It seems that the power side and output transformer are working good. I am going to pull it apart and do some investigating in the effects loop, preamp side of it here in a bit. The loud noise and hum when it is activated leads me to believe that there is something going on in the area where the pre amp and power amp are connected.

[bwheat]

Didn't find anything obvious, I measured the resistors in the board that the effects loop jacks, are on, and also in the section on the front board where the harness goes to. Everything I tested seemed to be in spec. Any ideas on where to look next?