Peavey TNT-100 Repair Problems

[TomCarlos]

Ahhhh.... that makes sense. Thanks Bill.

[Enzo]

WHat Bill said.

The part itself generates no heat and draws no current. SOme current flows through it, but not much. OH someone could point out that it does generate a miniscule amount of heat, not zero, but putting your finger on it would warm it up more than the circuit does. The heat of the heat sink warms it up and that changes the voltage drop across it. Very useful for tracking bias.

[Jazz P Bass]

Google "Diode Equation" for more info.
Here is a link that has a cool graphic that shows the changes that occur when the temperature is changed. (Diode Equation | pveducation.org)

[freegan72]

Guys:

I have a Peavey TNT100 bass amp on my bench. The schematic and layout is at jrem.webhop.org/tnt_100_schematic.pdf.

I narrowed the problem (no output) down to the output section (the signal follows through the collector of Q3).

My voltages showed that Q7 was blown, so I changed it out. When I fired the amp up (with a load on the output) I smoked R42.

So now I'm at an impass . . . and could used some help. After drewling over the schematic for a few stale afternoons at work I'm confused and need some direction . . . is the current through R47 coming from the feedback circuit (Q4& Q5)?

Could someone please take a peek and give me a clue? I don't need the answer, but I know I'm so close that it will kill me to pay someone to fix this just to find out it's something stupid I overlooked.

Thanks in advance,

John.

Are you working with the 19779 or 1974 version? I can get a schematic from the 1974 version from the back of the user manual, but it doesn't have as much detailed component information as I would like. Is there a more detailed version of the 1974 schematic out there? Thanks.

[Enzo]

Hi, welcome to the forum.

Since he refers to part numbers like Q17 or R122, he must have the 1979 one, the 1974 drawing does not use part numbers, it only identifies parts by type.

You can get any Peavey schematic by contacting customer service at Peavey and asking for it.

[The Dude]

<post deleted- incorrect information>

[Enzo]

I have both open on my screen. The 1974 has the drive transformer for the outputs. And a simple transistor preamp. The 1979 has ICs for the preamp, and a "regular" power amp. Neither is built in the preamp/power amp separate boards scheme of many PV amps.

The 1979 TNT100 has all transistor power amp. the 260C is similar but with an op amp front end on the power amp.

[The Dude]

Well. My apologies for the misdirection. I guess my memory isn't what it used to be. I deleted my post to save the op a wild goose chase.

[Enzo]

Oh brother man, I can barely remember the start of my sentences.