70's Peavey Bass 400 module problem

[Nyqusit5]

I replaced the drivers and I have an unclipped signal on very low power. But as soon as the power is turned up (still quite low), the positive part is clipped.

The ouptut signal is clipped without a load. When a load is connected, the clipping is more severe. I have checked all the op devices resistors and they seem fine. I have also checked the resistors and diodes connected to the drivers and they seem fine also. I'll go further up the signal chain and check the remaining resistors.

Thanks!

[Nyqusit5]

Well I have checked pretty much all resistors and diodes and they test all ok in or outside of the circuit (when necessary).
The clipping on the positive side occurs above a 10V limit on the output looking at the sine wave with the scope, and without a load. With a load, it occurs almost immediately.
The clipping is right there at the SPS761 emitters and collectors (not at the base of the first transistor obviously: the input signal is clean).

Still searching...

[nashvillebill]

Did you take the .001 cap out of circuit to remove the NFB (the one on the schematic just "below" /between the SPS761 LTP--jeez I wish Peavey had put labels on their components here...)? I'd pull it, then pull the 430C to isolate the LTP. Above the 430C is a 100 cap, have to checked it to make sure it's not leaking?

Bottom line, I'd try to isolate the LTP to eliminate it, then if the LTP is ok and you can get a clean sine wave through it, find out what is leaking. The 430C maybe. I've seen transistors that checked fine on my transistor checker (low voltage) but leaked badly at the higher rail voltages

[Nyqusit5]

Finally got time to finish this amp. Nashvillebill, you were right, the LTP was faulty too, so thank you very much for your help!