Recently my Fender Bassman 200 combo amp has been cutting out and crackling pretty frequently. I initially thought it was a bad cable but I had someone look at it and they said some transistors are overheating. Weirdly enough, to get the sound to come back, I usually just have to pluck a string really hard. Is there a fix for this? This is my first amp and I'd rather not get rid of it. Thanks
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Fender Bassman 200 Cutting Out
- Thread starter Levon Melkonyan
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- amp fender fender bassman
Does it have an fx loop?
If so, plug a patch cable from send to return and see if that cures the issue.
If so, plug a patch cable from send to return and see if that cures the issue.
- Feb 12, 2006
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- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
How old is the amp, is it a V2 or V3? Does it have an effects loop?
I can pretty much say for certain that it's NOT transistors overheating.
I can pretty much say for certain that it's NOT transistors overheating.
JeezyMcNuggles
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- Feb 23, 2018
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It's a short. It comes back when you hit your bass, right?
I had a little 15" combo back in the day that used to do that. Lasted a good while after, but eventually died. Only the output was affected though. Send, and headphone out worked fine. Just couldn't get sound coming out the speaker anymore.
My guitarist's swr 410 he has does the same thing. Smack the strings to turn it on. Hahaha. It's dying.
- Feb 12, 2006
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- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
No, actually it's the opposite of a short (it's an intermittent open circuit).
There are definitely more qualified folks to answer that. Basically sometimes that "fixes" symptoms, sometimes the symptoms mean other things are wrong. It's just a simple non-invasive thing to try. This time it worked, maybe next time it won't.
It's fairly common with amps that have some age. Dust or corrosion in the switching connectors. Hope that's all it is. Glad to help.
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The Return jack is often connected directly to the Send jack through a closed switch to allow the internal preamp signal to travel on to the power amp, when there is nothing plugged into the Return.
But, when there's a plug in the Return jack it opens that switch and interrupts the internal preamp signal from blending with the signal plugged into the Return and going to the power amp.
With a cable from Send to Return of the same amp that switch is bypassed! If it helps the problem that indicates some dirt, dust or corrosion on the switch is interfering with the signal. First, try running the plug in-&-out of the Return jack several times and remove the cable from both jacks. That should improve the problem somewhat. If still a bit crackley try a TINY amount of DeOxit D-5 fluid on a Q-tip into the Return jack to finish the repair, is that right, @agedhorse?
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JeezyMcNuggles
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- Feb 23, 2018
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Was the "overheating transistor" comment from a qualified technician, or just someone speculating because they heard that somewhere at sometime? Did the person saying this, even see or hear the amp acting up, let alone open it up?
There are a lot of people who think doing tech work is easy because it doesn't require a degree. And it doesn't, but it does require learning proper troubleshooting skills, and repair techniques. If those things are not brought to the table before a diagnosis is made, then they're wasting your time.
A good tech should not only be able to tell you WHICH ones are overheating, but why. And then he will tell you what needs to be done to fix it.
A lot of times, transistors overheat due to something else being wrong, not the transistor itself.
Other than the previously mentioned Send/Return patching method earlier, you're probably looking at some tech bench time. Try inserting/removing the plugs in the jacks several times, or even leave the patch in and see if that helps. Do not try using any type of cleaner without getting further guidance on proper techniques first.
Also... are any of the pots sounding scratchy, or cutting out as you move them through their full range of motion?
He was a computer repair guy I was referred to that apparently also knew about amps. He opened it up and also said that he did a full cleaning. I've left the patch cable in since yesterday though and it's been working perfectly since. And no, I've never had an issue with the pots.
- Feb 12, 2006
- 61,038
- 5
- 220,973
- Disclosures
- Development Engineer-Mesa Boogie, Development Engineer-Genzler (pedals), Product Support-Genz Benz
Apparently he knows nothing about amps... just sayin'.
Bypassing the return jack's normalling switch doesn't magically cure "overheating transistors".
Bypassing the return jack's normalling switch doesn't magically cure "overheating transistors".
I have a 25 year old Eden wt300 that's had a cable from effects send to return for 20 years.
Well it seems so far that you might have found an issue with dirty jacks. (They have little switches built into them that can cause these types of problems if not used.)
Computer guys are always running patches to fix problems, but they are always in the software. Only after several reboots, reloading the operating system, and maybe swapping out power supplies do they ever think about that physical patch cord over in the server rack.
If things continue to work well for you, there is no reason to not run it with the patch cord. (Unless it's just in the way.) If you haven't already, you can try inserting and removing the plugs several times. Sometimes doing this will be enough to clear away the layer of oxidation. You can also use a little De-Oxit cleaner. (Don't skimp here, the cheap stuff doesn't work as well. The wrong stuff might cause damage.) DO NOT spray the De-Oxit into the send/return jacks. Rather spray a little on the plugs and insert them into/remove them from the jacks several times.
My last few years on the job at the radio station, I had a self proclaimed computer guru always telling me how to keep the station on the air. His only claim to any technical knowledge was that he roomed with an engineering student in college.
I had a part that failed in an old piece of discontinued, and somewhat proprietary piece of broadcast equipment. I was going to contact the manufacturer as they still supported the gear. The "computer guy" without checking with me ordered something off the shelf from one of the run of the mill electronics distributors. Of course he let management know how he jumped right into action. He had the part overnighted but with the company mail room policies it still took two days to get it.
Two days later, he hands me the part to install. It was the wrong one. I told him the manufacturer had the correct part in stock and I'd order it. Then I told him to tell management that the repairs would be delayed. While he was doing that I had the correct part overnighted to my home. (Against mailroom policy.) They were back up and running within a few hours of my getting the replacement. For my part in this I got my butt chewed by management for calling out the "computer guy" because he tried to do my job.
Retirement suits me. The only thing I have to do is wake up in the morning.
Just repaired one of these. Opened it up and tapping on circuit boards led me to the board on the left rear with 2 six wire ribbon cables soldered to it. These cable wires will not tolerate any flexing at all as both ribbon cables snapped clean off, all 12 wires! Luckily I was easily able to strip the insulation away to be able to reattach to the board. I checked for shorted wire connections and found the soldering I had performed damaged three traces, so I bridged those wire ends to the next component on the trace on the board, again checking for proper continuity. Put everything back in and no issues since. In my case the ribbon cables had probably been damaged on initial assembly, with intermittent contact. Pics to follow.
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I have a Bassman 200 and the problem with this amp is: with or without anything plugged in, I get a sound that sounds like a breeze or wind blowing across a hot open microphone.
I was given this by a friend of mine who had taken it to a repair shop before, but it came out of the shop with the same problem.
I was a bench tech for years and I told him that I would look at. I’m trying to track down a schematic for it.
But if you can point me in the right direction that would be awesome. Thanks.
I was given this by a friend of mine who had taken it to a repair shop before, but it came out of the shop with the same problem.
I was a bench tech for years and I told him that I would look at. I’m trying to track down a schematic for it.
But if you can point me in the right direction that would be awesome. Thanks.
