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Ampeg BA115T Crackle/intermittent sound. (Adept amp techs welcome!)

Discussion in 'Amps and Cabs [BG]' started by ridethespiral, Aug 20, 2012.


  1. I've been having some problems with my Ampeg BA115T that have come and gone over the past year or so. I had got so frustrated with it that I even stopped playing bass for a while.. Well now I've got the itch to play :hyper:

    Now the best way I would be able to describe the problem is as if my bass' 9v is becoming weak. Playing low notes (E, A..) seems to work fine at lower volumes but once I start actually grooving and using more mid range, the problems become VERY apparent. When I start playing higher notes or a lot of mid range, the sound starts crackling. Sometimes I'll be playing and then it's like somene turned the volume down to ~2.

    So basically there's crackle (solid state clipping?.. it sounds like a crappy distortion) + intermittent volume fluctuations

    Originally, I had thought it was my bass due to the fact that the output jack was crackly. (My 04-12-2011 thread about the bass). I fixed this by resoldering the wires on the output jack as well as bending the contacts more inwards and cleaning them. Just to be absolutely sure (which I'm pretty sure it's not), I ordered an output jack and am waiting for it. The next thing I need to do is clean its pots or order new ones because they make sounds when I'm turning them, but do not cut out and work as intended other than a bit of noise.

    After all of this, I'm at the point where I know it's my amp. Then just a few weeks ago, I had left my amp on for about an hour after I tried to play through it when I came back and my sister told me there was a loud SIZZLE then a very loud POP/BANG. At that point I could smell a little bit of burnt electronics/plastic though I did not hear this happen since I wasn't in the room. Now the main problem is very consistent.

    NOTE: The headphone output sounds perfectly fine!

    Today I took out the power amp and removed the circuit to look at it. The solder connections all look fine. On the top of the board there is no considerably noticeable damage until I looked closer. Part of the pcb looks "cooked" and right below this cooked part are two resistors. I noticed the insulation on the pegs of the resistors looked very darkened, as well as the silicone that is on the end. Being as curious as I was, I decided to turn on the amp while hooked up to my bass and the speaker and play for 5 minutes. I touched the resistors and almost instantly they burnt my finger... What could cause this? and how can I fix this without paying $100+ to get it fixed. I'm fairly competent with soldering on circuit boards and the danger of the voltages so I wouldn't mind trying to fix this myself.

    Here are pictures of the resistors in question.

    IMG_20120820_180344.

    In this one, The circled part is where it looks cooked. It is very noticeable on the reverse side as well. The arrows are pointing to the extremely hot resistors.

    IMG_20120820_180831.
     
  2. Bump. :(

    Anyone know what I should be looking for? Afaik those two resistors should be running hot but is it too hot if it can burn my fingers?

    I've tried all kinds of leads. Should I try ordering replacement parts and upgrade components? If so which should I try replacing first?
     
  3. My bet is that theres a problem with the power amp but without going through it with a scope i couldn't be certain. It's not something you're going to be able to fix yourself i think.

    The resistors should get warm, it might be worth uprating them but i don't think it would fix your problem unfortunatly.
     
  4. BassmanPaul

    BassmanPaul Gold Supporting Member

    Aug 25, 2007
    Toronto Ontario Canada
    The cheapest, in the long run, way to go is to take the amp to a tech. He/she will be able to fix your problem without just throwing sundry parts at it.
     
  5. jdelemus

    jdelemus

    Jun 27, 2012
    Sounds like Ampeg has some quality control. I have a BA115HP I bought new a few years ago. It does the exact same thing but there are no obvious burn marks on the board. A guitar player I know bought the same amp a year later and his is also doing the same thing.

    My amp has now been at a shop for 3 months! I was mad than I bought a used Mesa WAlkabout. I now don't care if the BA115hp ever gets fixed.
     
  6. Damn not what I was looking forward to hearing.

    I've been looking at getting an orange terror bass 500W so I'm almost ready to let this thing become a massive paperweight.

    Don't really want to spend $200 fixing the thing when I could put it towards a new amp
     
  7. I believe I have fixed the problem by buffing the chassis and bolt/washer that connects the ground cable from the power cord. So far I have played the amp at about half volume for a few hours and it has been working just as it did when I first got it. (Minus the tweeter I disconnected)

    :)

    Still want a new amp though haha
     
  8. jfelser

    jfelser

    Aug 9, 2010
    What did you mean by "buffing the chassis and bolt/washer" as I have the exact same issue with my BA-115T? I really like the tone of the amp. This is sadly the second time I have had an issue with the amp. The last time it was under warranty :) Unfortunately, this time I am not so lucky:(

    Any help would be appreciated!
     

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