Transistor Part Numbers for Q130-Q139 in a Kole PH2-3000D

[whitejohnny]

Also, R204 (1K) is cracked but reads ok.

I shoulda checked the rails before installing outputs, I was in a hurry. (Worst time to do work). But with the neg 40 volts still present on pos speaker terminal, I suspect that the problems is elsewhere, right?

The rails come up ok, but drop and swing back up repeatedly. I disconnected the (-In) to the driver card earlier (to verify whether the neg voltage was present in preamp; it wasn't, but the -IN on the card still had the neg voltage.), didn't make a difference in symptoms.

PS.. before readings in above posts I replaced R173..

[whitejohnny]

Also, caps on driver card ok. Will run through with ESR meter after nap.

[Perry Babin]

Have you replaced R124 and R125 on the driver board?

[whitejohnny]

I replaced Q124 and Q125, also R173 and R190. I haven't done Q116 yet.

BTW, I misquoted the model number in the title, its QX1-3000D, sorry.

[whitejohnny]

So, anybody got a schematic on this one?

Is it something dumb I'm missing?

So is it safe for me to disconnect the output gates temporarily to make sure that the neg voltage isnt coming from an output - that it to narrow it to the driver board?

[Perry Babin]

You cannot disconnect the gate legs of the output transistors. If you do without removing the outputs completely, they will fail.

If you have a scope, you can remove the outputs, drive a signal into the amp and check the drive signal.

[whitejohnny]

Hey folks, on the driver cards for these amps there are twelve connections - the functions of some are obvious, but some are not - in the below list, what do 6 and 9 do?
1 IN+ (balanced input pos)
2 IN- (balanced input neg)
3 SG (signal ground)
4 +15 (pos op-amp supply voltage)
5 -15 (neg op-amp supply voltage)
6 SW ????
7 Vpp (pos rail?)
8 DRV (drives pos bank of outputs)
9 Out ????
10 PG (power ground?)
11 DRV (drives neg bank of outputs)
12 Vnn (neg rail?)

The silk screen marks 6 as SW and 9 as OUT, so what are there functions?

[whitejohnny]

Thanks Perry, I decided against it, lol.. Frustrating. I may strip it back down, go through it again.

[Perry Babin]

SW is the control terminal for the class D circuit. When near the positive rail, the driver board is disabled. When the voltage on the SW pin is near ground, the driver board is enables.

The OUT pin connects to the source of the high-side FETs and the drain of the low-side FETs. This is where you will see rail-rail oscillation on the output transistors.

[whitejohnny]

Ah, ok, thanks Perry. So is the OUT used for feedback or sensing purposes to prevent oscillation?

Had to keep the work queue flowing; came back to this amp this morning.
Pulled outputs.
Checked rails.
Pos rail approx 68 volts.
Neg rail approx -200 and offscale peaks.

LOL..

I think this might be related...