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Amp Problem: Help Help Help :( :( :(

DriftingByTheStormDriftingByTheStorm Posts: 8,684
edited August 2004 in Musicians and Gearheads
i just bought a Mesa Boogie DC3 all tube 30watt amp off of ebay, from some guy who claimed he had it retubed 6 months ago.

i haven't used it in any abusive fashion in the last week since i've had it.

today i was playing along to Hunger Strike at a very respectable volume (read: no where near PJ stage levels, and no where near what this amp is capable of pushing) ...

when all of a sudden it sounded like my guitar cable had swalloed a fucking analog synth with the envelopes smooshed ...

the amp started making all this crackling and snap crackle poping and this insanely obnoxious high piched squeel like the aforementioned analog synth ...

i checked my cables, i tried another power outlet, i let it sit off for a while ... eventually i unplugged everything from the amp, turned it on ... turned ALL KNOBS to ZERO ... and it still made this shitty noise. no matter which of the 2 channels was selected even. the only way to get it to stop while on, is to put it in standby, which don't count for beans.

i went to the back, the tubes smell kinda funny. like they were heating bad ... little bit of a burn smell ... THIS IS NOT NORMAL? i am no amp tech buy you tell me.

the only real fishy thing i noticed, is still not what i think the problem is. The DC3 has a disconnectable speaker wire that runs into a plug in the back of the amp. It was running along the inside of the case, pressed against a tube ... when i unplugged it and pulled it out, the wire had 2 burn marks on it ... one has melted the plastic slightly, and the other is just discolored ... i don't think the wire itself is burned, just the casing ... but even so, would that account for this god aweful racket, and the burned smelliing tubes?

when i turned the amp back off, and listened real close in the back, i could hear the tubes clicking, and sputtering as the cooled. IS THIS NORMAL?

any ideas what the fuck is wrong with this sweet little beauty i just paid 550 for?

doh doh doh ! ! !
If I was to smile and I held out my hand
If I opened it now would you not understand?
Post edited by Unknown User on

Comments

  • mccreadyisgodmccreadyisgod Posts: 6,395
    For general reference:

    http://trentino.best.vwh.net/

    It sounds like a speaker wire was sitting right alongside a tube, and when the tube warmed up, it heated through the insulation. Now, if the speaker wire was completely exposed and shorted out on the tube or the chassis, that might be the problem. The melted plastic insulation might be what smells like burning. Tubes are metal filaments in a vacuum in a glass casing (like a lightbulb), and they do get quite hot... a little ticking when cooling down is normal.

    Do any of the tubes glow bright? What color do they glow? This is a combo amp with an external speaker jack, right? Was this crackling noise the only noise coming through, or was the guitar signal coming through as well?
    ...and if you don't like it, you can suck on an egg.
  • DriftingByTheStormDriftingByTheStorm Posts: 8,684
    no seriously, bro.
    you just saved me a heart attack.
    i think you're telling me that it's just the wire.
    yeah, it's a combo amp.
    and yes, the guitar still comes through the speaker.
    it just makes some crappy crackling and whine noises.
    i guess the wire is just near a short or something.
    hopefully it don't cost more than $60 to repair. that would suck.
    still pissed the wire got burnt.

    glad it's not tubes.
    shew.
    -nik-
    If I was to smile and I held out my hand
    If I opened it now would you not understand?
  • mccreadyisgodmccreadyisgod Posts: 6,395
    Well, it still could be the tubes. If you play this thing a lot, you can go through power tubes in as little as six months. I would definitely have somebody check this thing out pronto, before you run the risk of serious damage or electrical shock.

    However, it does seem less serious than you first mentioned. Perhaps replacing the speaker leads (and stuffing them where they won't hit the tubes) may fix the problem.

    Let us know how it turns out...
    ...and if you don't like it, you can suck on an egg.
  • All Those YesterdaysAll Those Yesterdays Posts: 2,723
    Pre amp tube. Maybe one maybe all of the pre amp tubes. Either way not a big deal. Pre amp tubes can be changed at home, and you don't have to rebias them like power amp tubes. Get that wire off the tube though, it won't help anything in the future. Also they could of been new tubes, during shiping the filaments could be shaken up. Tubes are tricky things some time. Sometimes they last a year, sometimes a month. Its all just luck. Get what you need at the tube store.
    E. Lansing-98 Columbus-00,03,10 Detroit-00,03 (1&2),06, 14 Cleveland-03,06,10 Toledo-04, Grand Rapids-04,06 London-05, Toronto-05, Indianapolis 10, East Troy (1&2) 11, Chicago 13, Detroit 14

    https://www.facebook.com/aghostwritersapology/
  • Pacomc79Pacomc79 Posts: 9,404
    It's more than likely a pre amp tube, however the wire is probably melted and needs to be replaced.

    You need to get the amp checked out. It's not worth you getting shocked over. I'd unplug it and take it to a tech. It's very VERY dangerous to mess about internally in tube amps. Capacitors hold lots of voltage long after you turn them off and you can get shocked and die or get badly burned. It's worth the money to take it to someone and have them check it out for you. It's likely minor though. Taking it to a tech is just the best way for you to make sure it will be fixed properly.

    you can find one locally at http://www.webervst.com
    My Girlfriend said to me..."How many guitars do you need?" and I replied...."How many pairs of shoes do you need?" She got really quiet.
  • DriftingByTheStormDriftingByTheStorm Posts: 8,684
    hey pac, mmisgod ...

    i just spoke to a guy, Mike Kropotkin, who is listed as an amp tech in my area, off of the site that Pacoma listed (HEY THANKS :)

    he had a few things to say

    1. if it wasn't the tubes on my Mesa, he won't really work on it. he doesn't do internals on Mesa \ Boogies , too complex. If it were a preamp tube the minimum labor charge would be $70

    2. he says it sounds definately like a tube problem, and absolutely is not the wire. i wen't over the wire several times with him, and he stood firm that it wouldn't matter even if it was severely burned. it would just stop making sound.

    3. i told him that the noise occured regardless of what channel i was on. and even still after the instruments were unplugged, and EVERY level was turned to zero. He said this is interesting because that should kill all the tubes, and there shouldn't be any noise. Then he said there is still one tube in play with all the volumes down: THE EFFECTS LOOP TUBE ... so he is guessing its an effects loop tube.

    GODDAMN. i don't want a blown tube.
    i just spent good money on an amp. doh. oh well.
    live and learn. what's a little green to have an amp thats clean?
    ok that was borderline homoerotic right there.

    anyway.
    i'll keep you updated.
    i'm gonna query by email this company he refered me to, MusicTechnology.com ... they're in springfield, va and look VERY qualified.

    Thanks again you 2.
    edit- hey AllThoseYesterdays, sorry to leavey you out. didn't even see the reply. THANKS for the responses guys.
    just sent off a query to MusicTechnology, we'll see what they have to say.

    i am NOT comfortable changing any tube myself.
    i'd just end up spending more on ANOTHER tube after i broke the new one i was trying to replace. i am HORRIBLE with electronics, and manual labor of any sort.
    If I was to smile and I held out my hand
    If I opened it now would you not understand?
  • Pacomc79Pacomc79 Posts: 9,404
    Is it kind of a boominess? because if it is, I'm betting the E/L tube is a good bet.

    Mesas, Extremely highly engineered. Great when they work not so great to work on. Good luck with the guys in springfield.

    However Mesa is a very small company out in So Cal, If you call them someone "a real person" will probably answer the phone.

    No doubt they can help. http://www.mesaboogie.com

    http://www.thetubestore.com may help for future reference.

    good luck. Chances are it's small, I just would unplug it though to prevent any further damage. Sorry about the problems, but once you get it back and it's right I think it will all be worth it.

    Mesa's are fantastic amps.

    Cheers, P.
    My Girlfriend said to me..."How many guitars do you need?" and I replied...."How many pairs of shoes do you need?" She got really quiet.
  • All Those YesterdaysAll Those Yesterdays Posts: 2,723
    Originally posted by All Those Yesterdays
    Pre amp tube. Maybe one maybe all of the pre amp tubes. Either way not a big deal. Pre amp tubes can be changed at home, and you don't have to rebias them like power amp tubes. Get that wire off the tube though, it won't help anything in the future. Also they could of been new tubes, during shiping the filaments could be shaken up. Tubes are tricky things some time. Sometimes they last a year, sometimes a month. Its all just luck. Get what you need at the tube store.


    Capacitors are not sitting out in the open. Especially on newer amps. They stopped doing items like that back in the 70's. Yes Capacitors do hold their charge, until they are grounded. But you won't be exposed to them when changing the pre-amp tube.
    E. Lansing-98 Columbus-00,03,10 Detroit-00,03 (1&2),06, 14 Cleveland-03,06,10 Toledo-04, Grand Rapids-04,06 London-05, Toronto-05, Indianapolis 10, East Troy (1&2) 11, Chicago 13, Detroit 14

    https://www.facebook.com/aghostwritersapology/
  • Pacomc79Pacomc79 Posts: 9,404
    Originally posted by All Those Yesterdays
    Capacitors are not sitting out in the open. Especially on newer amps. They stopped doing items like that back in the 70's. Yes Capacitors do hold their charge, until they are grounded. But you won't be exposed to them when changing the pre-amp tube.


    If there is an internal problem, changing the tube does nothing but blow another tube. Sure it's probably a tube problem but we can't definitively say that without seeing or hearing the amp.

    Capacitors can hold thier charge even after the amp is unplugged. it's probably not best for him to be opening up the cabinet (to fix any wiring) That was my point. I was erring on the side of safety.

    http://www.mesaboogie.com/Product_Info/F-Series/F-30/F-30CloseUp/F-30-ChassisLg.html


    that's an internal picture of a new F-30 chassis. Not something you want to mess with if you aren't qualified. That's all I was saying.

    I agree with you though it's more than likely a pre amp or E/L tube.
    My Girlfriend said to me..."How many guitars do you need?" and I replied...."How many pairs of shoes do you need?" She got really quiet.
  • mccreadyisgodmccreadyisgod Posts: 6,395
    Well, a new 12AX7 tube for the FX loop shouldn't cost more than about $10-15, and they're as easy to change as a lightbulb. If that's the deal, then you shouldn't be in too bad...

    Keep us posted.
    ...and if you don't like it, you can suck on an egg.
  • All Those YesterdaysAll Those Yesterdays Posts: 2,723
    Originally posted by All Those Yesterdays
    Capacitors are not sitting out in the open. Especially on newer amps. They stopped doing items like that back in the 70's. Yes Capacitors do hold their charge, until they are grounded. But you won't be exposed to them when changing the pre-amp tube.

    I'm not trying to slam anyone, he seems concerned about cost, and taking it to someone, is going to cost money. Usually if their are any problems other than tubes, its going to pop the fuse. I'm willing to bet that a service guy is just going to be popping in a tube, without even opening it up. But with everything their is always a situation where things are differently.
    E. Lansing-98 Columbus-00,03,10 Detroit-00,03 (1&2),06, 14 Cleveland-03,06,10 Toledo-04, Grand Rapids-04,06 London-05, Toronto-05, Indianapolis 10, East Troy (1&2) 11, Chicago 13, Detroit 14

    https://www.facebook.com/aghostwritersapology/
  • Pacomc79Pacomc79 Posts: 9,404
    Originally posted by All Those Yesterdays
    I'm not trying to slam anyone, he seems concerned about cost, and taking it to someone, is going to cost money. Usually if their are any problems other than tubes, its going to pop the fuse. I'm willing to bet that a service guy is just going to be popping in a tube, without even opening it up. But with everything their is always a situation where things are differently.



    yeah man. I agree with you. I'm just being overly cautious.
    My Girlfriend said to me..."How many guitars do you need?" and I replied...."How many pairs of shoes do you need?" She got really quiet.
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