Bugera 6260-212 help!

[The Dude]

.... and, to be clear, I gave you 2 things to measure on each jack- 4 total measurements. Imagine the lines I drew are wires and check each wire. You are saying all 4 measurements were .486 ohms?

[frpax]

.... and, to be clear, I gave you 2 things to measure on each jack- 4 total measurements. Imagine the lines I drew are wires and check each wire. You are saying all 4 measurements were .486 ohms?

Alright. I re-diagrammed it:



I labeled each of the 5 leads that come off of each jack -> into the board. A B C D E As you cab see above.
Here are the resistance readings for every combination:

A-B 0.1
A-C 0.486
A-D 0.1
A-E 0.486
----------------
B-C 0.485
B-D 0.1
B-E 0.485
----------------
C-D 0.485
C-E 0.1
----------------
D-E 0.485

BOTH jacks read exactly the same resistance readings

[The Dude]

C-E and A-B are the internal switches of the jack and both appear to be working. We can move on.

[frpax]

C-E and A-B are the internal switches of the jack and both appear to be working. We can move on.

OK! I'm ready! Lay it on me!!

[DrGonz78]

You said you are handy with a solder iron...? Go for it and hit a bunch of those solder joints. I mean that is the worst and best advice all at once. Personally looking at the pictures it is very hard to tell if what I am seeing are really bad solder joints or not. However, some of the joints in the picture make me think they look bad, but I always feel that way with these new amps. Get a magnifying glass and look at each of the joints on that board closely. If they look even a bit suspect while magnified then reflow the joint and move on. Just be conservative and careful not to damage the PCB circuit.

[frpax]

You said you are handy with a solder iron...? Go for it and hit a bunch of those solder joints. I mean that is the worst and best advice all at once. Personally looking at the pictures it is very hard to tell if what I am seeing are really bad solder joints or not. However, some of the joints in the picture make me think they look bad, but I always feel that way with these new amps. Get a magnifying glass and look at each of the joints on that board closely. If they look even a bit suspect while magnified then reflow the joint and move on. Just be conservative and careful not to damage the PCB circuit.

OK Gonz, so after I reflow any solder joints on the preamp tubes that even look suspicious, then should I reassemble it (as much as necessary) and test it out? Or is there something else I should do while the whole thing is cracked open?

[DrGonz78]

OK Gonz, so after I reflow any solder joints on the preamp tubes that even look suspicious, then should I reassemble it (as much as necessary) and test it out? Or is there something else I should do while the whole thing is cracked open?

Since we are just re-flowing joints and have really not pinpointed the fault I would just check to see if this one thing we are trying makes a difference. I have worked on an amp where after 2 minutes the sound cut out and I did some re-flowing of joints in specific areas, only to find it now took 8-10minutes for the audio to cut out. At that point I had to pinpoint what joints I had hit and figure out which were the culprits. At that point I had to fully remove that crap re-flowed solder and put down fresh solder. So, my best advice in this instance is to fully remove the lead free crap solder and add some good leaded solder joints.

If this idea does not work then we need to trace the audio in the preamp circuit and discover where the signal is dropping out. Honestly, tracing the signal would be the first step and re-flowing solder would be the next if that what was called for. In your case we are assuming you don't have very much audio testing equipment at hand.

[frpax]

Since we are just re-flowing joints and have really not pinpointed the fault I would just check to see if this one thing we are trying makes a difference. I have worked on an amp where after 2 minutes the sound cut out and I did some re-flowing of joints in specific areas, only to find it now took 8-10minutes for the audio to cut out. At that point I had to pinpoint what joints I had hit and figure out which were the culprits. At that point I had to fully remove that crap re-flowed solder and put down fresh solder. So, my best advice in this instance is to fully remove the lead free crap solder and add some good leaded solder joints.

If this idea does not work then we need to trace the audio in the preamp circuit and discover where the signal is dropping out. Honestly, tracing the signal would be the first step and re-flowing solder would be the next if that what was called for. In your case we are assuming you don't have very much audio testing equipment at hand.

As far as I know, I don't have ANY audio testing equipment. I don't even know what I'd need!

[The Dude]

...... we need to trace the audio in the preamp circuit and discover where the signal is dropping out. Honestly, tracing the signal would be the first step and re-flowing solder would be the next if that what was called for. In your case we are assuming you don't have very much audio testing equipment at hand.

^^^^^^That! Stepping back, I would not have disassembled the amp without some troubleshooting and a plan. Since you had already done so, we were trying to help the best we could with the circumstances given. Saying that, I would reassemble the amp and do some troubleshooting. Look for a voltage on a tube that is missing. Trace the signal, as DrGonz78 says. Etc. At this point, we are just guessing with no real plan of attack or knowing what the actual problem is. Given your experience level, I would recommend starting with RG's tube amp debugging page and see if that helps. Again, you really need to troubleshoot the amp rather than "shotgun" it.

Tube Amplifier Debugging Page

[DrGonz78]

A simple DIY signal tracer is not expensive to build. Here is another link that might help answer questions about making one or point you in the right direction. RG's troubleshooting guide that The Dude linked is great too!

Troubleshooting your Amp ? Billm Audio

Edit: Also realize the main reason we dismantled the beast was to see if some component blew up and general inspection. Since nothing is obviously blown out we have to take other measures. Not all wasted if you see some bad looking solder joints and hit those while you have it apart just as long as you don't get carried away. Just hit one's that look real bad and if none appear to be bad then move along.

[frpax]

OK, so I put the thing back together, making sure that everything I unplugged went back to the same spot (hoping I was right!); put the chassis in the cab; hooked up the speakers; and then plugged into the wall......


Nothing spontaneously started catching fire, so I took that as a sign that everything was "so far, so good".


Hooked up a guitar and played the thing for at least 20 minutes without any inkling of a problem. Various volumes and different channels and all. Go figure.
I really didn't DO anything to it except reflow 3 or 4 preamp tube socket joints. But, I guess whatever WE did (this was most definitely a TEAM effort!), did the trick!


At least for now.

Thanks Dude, DrGonz, g1 and Enzo for guiding me through this! Hopefully I'm back in business!!

[frpax]

Alright! I had a couple of hours of playing time tonight, and it appears that the amp is working just fine!

Once again, MANY THANKS to those that helped!

I just hope it STAYS fixed! LOL!!

[boots]

I read this thread with interest because I just had a 6260 that had weird intermittent problems. It was full of dry-looking solder joints, and I re-soldered a lot of them. Seemed that I was losing the DC filament voltage somewhere between the regulator and the tube sockets. I never could find the problem, and sent it to another fellow amp tech, and he couldn't figure it out either. We declared the amp to be not economical to repair. I suspect there might be a hairline crack in the board that we can't find. It might be possible to figure it out, but it takes many hours of technician time to do so, and it just isn't worth it.

We weren't able to get ahold of a schematic, and Bugera does not release their schematics or parts to the public - only to authorized service centers. We called a service center and asked if we could buy a new PC board, and they said they have to be sent from China, and it typically takes "many months" to get them.

I have not been impressed with the design or build quality of these amps, nor with the lack of support from the company. Just my .02 worth. Glad you were able to fix yours by re-soldering. I can say that the amp I had on my bench was full of bad solder joints, so it seems to be a typical problem.

[DrGonz78]

I remember repairing the 6262 and it had a melted plastic molex connector on the filament lines. Most of the newer ones don't have that issue since they straight solder them to the board at the factory now. Just like the pic in this post, look at post #1. Not sure if this applies to the 6260 amp but just thought to mention it anyway.

http://music-electronics-forum.com/t10249-2/

[The Dude]

I read this thread with interest because I just had a 6260 that had weird intermittent problems. It was full of dry-looking solder joints, and I re-soldered a lot of them. Seemed that I was losing the DC filament voltage somewhere between the regulator and the tube sockets. I never could find the problem, and sent it to another fellow amp tech, and he couldn't figure it out either. We declared the amp to be not economical to repair. I suspect there might be a hairline crack in the board that we can't find. It might be possible to figure it out, but it takes many hours of technician time to do so, and it just isn't worth it.

We weren't able to get ahold of a schematic, and Bugera does not release their schematics or parts to the public - only to authorized service centers. We called a service center and asked if we could buy a new PC board, and they said they have to be sent from China, and it typically takes "many months" to get them.

I have not been impressed with the design or build quality of these amps, nor with the lack of support from the company. Just my .02 worth. Glad you were able to fix yours by re-soldering. I can say that the amp I had on my bench was full of bad solder joints, so it seems to be a typical problem.

Respectfully, it should not be a difficult repair to find a missing/broken/intermittent filament connection. Run jumper wires if you need to. I can't imagine giving up on an amp for a filament problem.