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Peavey VB2 has melted down

Discussion in 'Amps and Cabs [BG]' started by Mr_Sore_Fingerz, May 12, 2010.


  1. Ok so after doing extensive troubleshooting and forum searching I am left with little actual help that I've found. Let me state what I'm using and what I've done already...

    Ibanez SR500 into a peavey VB2 with all stock tubes and components going into a 4-ohm Kustom 2x15's cab. I let my amp warm up a good 10-15 minutes on standby and plug my bass in. I play at 9 o'clock volume and gain at 10 o'clock for maybe 1 or 2 minutes. All of the sudden I hear a LOUD and painful "BAAAAANNNNNNNN" and go to standby immediately. I assume its my bass preamp battery and go to change it. I plug the bass back in, go off standby...same sound. I turn the amp off and consider that it might be my cable, so I switch to a different cable and have the same results. I even tried the high gain jack with my bass turned down to no avail. After doing that, I got absolutely no sound out of the amp whatsoever. I troubleshot everything and even plugged in another nearby head into my cab and everything worked perfectly fine.

    Just on a hunch, I tried to use my DI out into the PA and it worked just fine and sounded good. All my power tubes light up and look fine (although that doesn't mean anything, from what i've read). I noticed the tone sounded a little on the rancid side last practice a week ago, like I couldn't get a fat or solid sound...it was just buzzy and unpleasant. My hunch is it's either the 12AX7 driver near the power section or a power tube, Any suggestions on which type of tube it could be (power or driver) so I could anticipate how much money I'm in?

    I'd like to get a tube tester that just tells me if a tube is bad or not so I can skip having to drive all the way into houston to find a decent tech (a good hour or two drive) and fix it myself. Please do not post the link from tone-lizard.com in a response, I've read it already. I'm not testing for microphonics or anything like that, I'd just like a quick fix for this at the moment, a full retube will be done later when I have more money. I could do the "swap it out tube by tube" trick but if it's multiple tubes that have failed or I order more tubes than I need to, then how does that help me? lol.

    Suggestions on a decent, inexpensive tube tester or any good amp techs in the Houston, TX area would be of the utmost help
     
  2. Firstly tube testers will not tell you if your tube is good or bad except for emission. The results have to be interpreted. To buy one you're looking at several hundred dollars for something like one of the Kickok range.

    I would have thought that your amp would still be under warranty. Call Peavey and see what they suggest. Do NOT open the amp unless you have extensive experience working on high voltage tube electronics. Safety is most important.

    Paul
     
  3. Hi.

    +1 for everything Paul said.

    Some people have sort of given up on tube testers and are testing the individual tubes on a SE class A amps. With a few clever adjustment- and metering points, quite a bit of the tubes characteristics can be found. You obviously do need an o'scope, signal generator, multimeters, knowledge how to use said equipment etc.
    And most importantly, You have to know what you're doing.

    Regards
    Sam
     
  4. True, I do realize they are totally different animals but I am a system builder for computers so I'm handy with electronics and know the do's and don'ts for the most part. A PSU on a computer operates much the same as the transformer on a tube amp in that it retains voltage for long periods of time and can kill you.

    Just wasn't sure if anyone could zero down what type of tube it would be (the preamp 12ax7's, 12au7, or el34 power tubes). I really love this amp a lot and the tone is great, I might just wait until I have enough dough to do a full retube on it. I have a sansamp RPM for now so im not rigless but I'd rather be up there using my VB2 lol.

    Anybody know of some good techs or a site or place to look for some?
     
  5. hdracer

    hdracer

    Feb 15, 2009
    Elk River, MN.
    How long have you had it? It has a 5 year warranty.
     
  6. BbbyBld

    BbbyBld

    Oct 13, 2005
    Meridian, MS
    If the master volume had no effect on the noise, it's probably in the power amp section.

    You may have had a shorted power tube. Since you are getting no sound at all now, this bad tube probably blew the high voltage fuse located inside the chassis. You can have a tech remove the chassis to see if F2 is blown, which would indicate a bad power tube. Another way to check to see if the high voltage is still there is to use a tuner. You can turn the amp on, but leave the standby off. Plug your bass into the input jack, take another cable and connect a tuner to the send jack on the amp, and then play. If the tuner is getting signal, your high voltage is still there and you're in luck. If you get nothing, there's a 99% chance you have a bad power tube.

    If you still have high voltage, it's possible that it could have been the 12AT7 driver tube since you say it started sounding funny for a while before it made the loud noise. You should be able to get one of these for under $10. This could be tested by replacing the 12AT7 with one of the 12AX7s temporarily and plugging a bass into the return jack. If it works like this, then the 12AT7 is probably bad. It's also possible that your driver tube socket has a loose connection. A tech can fix that. I wouldn't bother with a tube tester in this case. They only tell you whether or not the tube is doing anything at all or nothing. Most "bad" preamp tubes will look fine on a tube tester.

    If you think you need a tech, I suggest sending the amp back to Peavey for repair. This usually works out better in the long run. You can get shipping information from the Peavey website in the support section.
     
  7. Thank you very much, this was quite a helpful response.

    I bought the amp from a fellow TB'er and I'll have to ask him if he registered it in his name or no, so that I can take advantage of the warranty on it. I too had a hunch that it was the 12AT7 since the DI on the amp worked just fine. The amp sounded fine as I was warming up before the "BAAAANNNN" sound, but it sounded funny the previous week at high-ish volumes.

    I'll probably send it off if at all possible, but I'm hoping the warranty transfers lol.

    Thanks again Bbbybld! :D
     

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