Peavey TNT 130, DDT forever active

[Basslord]

Hi Guys.

I receive has a gift a blown Peavey TNT 130 and I'm trying to fix it. After re-soldering the input connectors ( they were broken ), I replace the blown speaker with an old PA speaker that I have.

When I connect an audio signal to the high input, I hear everything perfectly on the speaker, but randomly, the DDT led turns on and stays on and the amp looses power and the gain controls are deactivated ( I'm guessing is some protection mode of the amp ).

I check all the resistors and they are good. I notice that when I unplugged the speaker connector on the board and reconnected again, the DDT led turns off and everything works fine but only for a couple of minutes.

Any suggestions ???

[Gibsonman63]

Try testing with an external speaker to isolate the electronics from the vibration of the speaker.

Check the obvious stuff like connectors. Check the larger capacitors. Sometimes when the amp gets thrown around or played hard, the solder connections can break.

[Basslord]

Mistake

Thanks Gibsonman. I found a mistake that I was doing, the impedance of the speaker that I was connecting was 8 ohms, the amp is designed for 4 ohm speakers. Luckily I have another 8 ohm speaker so I connected them in parallel.

With this change the DDT light was not coming on and the amp appears to work fine. Is there any other test that I should perform to the amp, I'm worried wondering why the original speaker was blown on the first place. Any suggestions ??

Also I'm planning to replace the speaker with this eminence speaker (http://eminence.com/pdf/legend-ca154.pdf). Do you think it will run smoothly on my amp ???

Thanks for all your help

[Gibsonman63]

Glad you got it working. If I am not mistaken, your amp is 20+ years old. Speaker cones (generally) are made from paper so it is hard to say what caused the failure. I am no expert on speakers, but for that amp, I would try to get something effecient. I picked up a TNT 130 last year as a throw down bass amp for my studio for $125, but I found it to be a bit underpowered compared to my drummers right foot.

[Basslord]

SAD

I'm sad, after cleaning all the knobs and contacts, and reinstalling the amp in the cabinet, i plugged in and AGAIN!!!! the same thing, the amp doesnt have power, the ddt light is on and the gain knobs doesnt work.

I was mad hahah and that help me to find something if i hit the amp where the inputs are, the problem stops, at least for some minutes, any ideas that might help ??

thanks...

[Basslord]

Finally Fix It.

Ok, just to help anyone in the same situation. The real problem was that a couple of cement resistors located in the power amp were not welded properly. After a couple of welds the amp is working like new now.