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Help with Peavey TNT 115 low output

Downlowd

Downlowd

Oct 11, 2007
408
1
Houston (Westside), Texas
www.thebrandedband.com
#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.
 
#10
BassmanPaul said:
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.
Click to expand...

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?
Yes___

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?
Yes___
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___
 
#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
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.
 
#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.

Paul
 

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