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Help with Peavey TNT 115 low output

Discussion in 'Amps and Cabs [BG]' started by Downlowd, Mar 31, 2009.

  1. See second page....I found the problem and fixed it.

    I am hoping someone can give me some advice on where to start checking to figure out whats wrong with my Peavey TNT115. Here's the symptoms;

    I have to turn the gain and master control to 10 to get any output from the amp, even then the output is very low. When I plug into the effects return/preamp in the output is a bit louder.

    I took it apart and see nothing obviously burned or damaged. The three fuses are good. I took them out and checked them with a DVOM. The jacks and knobs appear to be securely soldered to the board still.

    The power chord is damaged where it goes through the chassis. The grommet is gone and the white and black wires are missing insulation from rubbing on the chassis. I assume that at some point these wires shorted to the chassis and damaged something in the amplifier circuit.
    I'm going to get a new power chord (also the ground is broken off the plug) and grommet today.

    Any ideas an where to start?
  2. Downlowd... That a tough break alright man... Ya need to get on the horn and ring up the kind folks in the Tech dept at Peavey. They will try to walk you thru the current isuue you are having, like they have for me on more than one occasion. Please don't power that amp again before the power cord is properly replaced/terminated.
  3. I bought a new power chord and a "strain relief"grommet, I will install those first. I may try Peavey, I was just hoping someone had a similar problem and could say... sounds like this...check this.
    I'll probably start with the transformer voltages. Anyone else?
  4. Anyone???
  5. I had the same problem with both of my tnt115's and i tried everything. I changed the capasitors, rewired most of the jacks in a series of two months, i called peavey but to no avail. there pretty good amps but when they die, there dead. In my experience anyway, good luck.
  6. I'm going to fix the power chord tonight and start checking the voltages at the transformer.... I'll probably end up with a Peavey coffee table also...:crying:
  7. I've got two! i plan on parting them out and making P.A. subs out of them.
  8. Anyone have any suggestions?
  9. Take it to a tech and get someone who knows what he is doing to fix it for you. You will probably just make things worse.

  10. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Au contraire, Paul - I just got this email and I'm sure the OP can fix it with the proper online help (email follows):

    Hi! I'm your friendly amp technician! I live perhaps thousands of miles outside the range of hearing and seeing your amp - even when it's turned up and working! So I've devised this handy questionnaire! In order to help me more efficiently diagnose and repair the problem with your amplifier please respond to the following points:

    1. Describe your problem:

    2. Now, describe your problem accurately:

    3. Speculate wildly based on faulty knowledge about almost everything
    just what's the cause of your problem:

    4. Please indicate the severity of your problem:
    A. Minor___ B. Trivial___ C. Minor___ D minor, the saddest of all keys___

    5. Nature of problem:
    A. Sounds bad___ B. Sounds really bad___ C. No sound___
    D. Strange smell___ E. Smells really bad twice___

    6. Was your amp plugged in?
    Yes___ No___

    7. Was it turned on?
    Yes___ No___

    8. Did you try to fix it yourself?
    Yes___ No___

    9. If so, did you make it worse?
    Yes___ Yes___

    10. Did you have a "friend" who "knows all about amps" try to fix it
    for you?
    Yes___ No___

    11. If so, did they make it worse?

    12. Have you read your manual?
    No___ No___

    13. Do you have the manual?
    Maybe___ No___

    14. Are you absolutely SURE you read the manual?
    I was going to___ No___

    15. If you think you read the manual, do you think you UNDERSTOOD it?
    Yes___ No___

    16. If YES, explain why you can't fix the problem yourself:

    17. What were you DOING TO your amplifier at the time the problem occurred?

    18. If you answered "nothing", explain why you think there's a problem:

    19. Do you have another amp you can use while you wait to take this one
    to a repair shop like you should have done in the first place?
    Yes___ No, I prefer to be out of commission longer___

    20. Are you sure you're not imagining the problem?
    Yes___ No___

    21. Does the clock on your DVD player always blink 12:00?
    Yes___ That's a clock?___

    22. Do you have an independent witness to the problem? (Does not
    include drummers)
    Yes___ No___

    23. Have you given the amplifier a good whack on top?
    Yes___ No___

    24. Did the amplifier catch fire?
    Yes___ Not yet___

    25. Has the foam or insulation inside your speaker enclosure
    ever caught fire?
    Yes___ No___ Huh?___

    26. Did the insulationy stuff inside your speaker BOX catch fire?
    Yes___ No___

    27. If so, did you replace it with an approved dampener?
    No, enough beer gets spilled in there to keep it safe___
    No, the cat whizzes in there after a good scratch on the
    carpet anyway___
  11. Thanks for the help.
  12. greenboy


    Dec 18, 2000
    remote mountain cabin Montana
    greenboy designs: fEARful, bassic, dually, crazy88 etc
    Good luck with that.
  13. I knew that you'd be along any minute GreenBoy! :)

    That post always gives me a smile!

  14. Glad he helped you...anyone have any legitimate advice?
  15. I've given you legitimate advice as has GreenBoy in his own unique way!

  16. You did and thanks, but I was aware of that option from the start. I have taken amps to local techs without much luck. I have fixed several amps with minor issues in the past. I was just hoping someone had a similar problem and could point me in a direction that would save some diagnostic time. I took Greenboys post as condescending and it did nothing to address the original post.
  17. johnk_10

    johnk_10 vintage bass nut Supporting Member Commercial User

    Feb 16, 2008
    Thousand Oaks, CA
    John K Custom Basses
    you might try taking the signal out of the effects loop and running it into another amp to see if it is weak or not. if it is, its in your preamp.
    if not, try running a signal into the power amp input to see if there is low level or not. if it is weak, its in your power amp.

    this won't fix it, but it'll give you a better indication as to where to start looking.
  18. roschmbo


    Dec 13, 2008
    Peavey amps with built in power chords. What'll they think of next?
  19. OK...thanks. I didn't try the preamp out to another amp. When I plug into the preamp in, I do get output to the speaker, but it is low. I get nothing through the main input, so I suspect the poweramp. I will try what you suggest tonight, that should help for sure.

    And yeah roshmbo, if it had a power chord like my Little Mark it would probably still be working. I'm sure the exposed wires that the previous owner ignored are what caused the failure.
  20. In defense of GreenBoy's post, it IS, unfortunately, very accurate. People will insist on opening a malfunctioning amplifier to "take a look" at what might be wrong without the slightest clue of the technical side. Resistors and other passive devices do not simply burn up for the sake of it or just to give you, the owner, a hard time. There has to be something wrong, most likely unseen, to cause the problem. I have had to repair more than a few units that the owner has attempted to fix (as have all techs), invariably the repair has cost much more than the original problem would have done.


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