Peavey windsor power amp mod problems.

[Captain chunkulus]

Okay, so I've been modding amps for a while as a hobby. I've even built my own amp from scratch. However I recently picked up a peavey windsor as a platform for modding and have run into a snag. Long before I heard about any "marshall" mods I had come across a schematic for the windsor and thought, this could be very similar to a jcm800. So, when I got one to fool with that's what I set out to do. Now what has thrown me for a loop is that after I modded the preamp, no issues. Sounded better than stock but I felt that I needed to go ahead and mod the power amp and change the phase inverter to a long tailed pair. It wasn't that hard to do honestly but after the mod I noticed a HUGE loss of output volume. I have gone over my work at least a dozen times even with a continuity meter and can"t find issues with miss wiring or wrong parts. Has anyone else here experienced this after modding the phase inverter in this amp? I'm kinda at a loss. Any help would be awesome. On a side note just for info sake, I dud use  a 470 ohm resister and not a 470k on the cathodes of the phase inverter tube. I'm also including a schematic of what was done.

[Captain chunkulus]

Also, I removed r15, r16, r17, r18. Changed r32, r33,r34,r35 to 5.6 k's and tied pin 1 to pin 8 on all 4 el34s.

[PRR]

Voltage readings. Compare to any known-good long-tail. I suspect a big difference.

[sluckey]

Point "A" on your schematic must have a capacitor that connects back to the preamp circuit (not shown). Do you have such a cap?. And get voltage readings as PRR suggested.

[Captain chunkulus]

I will check  the voltage. Here us the rest of the schematic. Looks like there is a coupling cap comming out of the effects Loop c13 I'm pretty sure.

[Captain chunkulus]

Power supply schematic.

[Captain chunkulus]

Okay, where the 82k and the 100k plate resisters connect to the plates reads 171volts and 168 volts. The voltage going into the resisters is 256 volts.

[sluckey]

Need all voltages for pins 1, 2, 3, 6, 7, and 8. Also measure the voltage at the junction of the 10K, 1M, 1M, and 470Ω on your added terminal strip.

[Captain chunkulus]

Pin1, 165v
Pin2.  27v
Pin3, 27v
Pin6, 167v
Pin7, 18v
Pin8, 27v

10k 1m 1m 470ohn junction  27v

[92Volts]

You mention a 5-point terminal strip but I see 5 junctions total, A, B, C, D, and the one shared by all the resistors. Usually 1 terminal of the strip is grounded through the physical mount to the chassis. Is every point you used independent and floating?

It seems you have a 10k feedback resistor in the same position as VR1 (5k pot) here: http://www.aikenamps.com/index.php/the-long-tail-pair

With all else equal this would provide more feedback (a little less volume), but the entire feedback/presence circuit is different. Maybe disconnect or ground out NFB temporarily to see what kind of difference it makes?

[Captain chunkulus]

I do have it floating. But the 10k ties to a 4.7k to ground. I don't have a 10 k there it's 2 1megs tied to the 470ohm, then 1 10k then a 4.7 k to ground. Pretty much spot on to this schematic I'm posting.

[Captain chunkulus]

I will try the feedback thing when I get home.  Thanks for your help.

[92Volts]

I do have it floating. But the 10k ties to a 4.7k to ground. I don't have a 10 k there it's 2 1megs tied to the 470ohm, then 1 10k then a 4.7 k to ground. Pretty much spot on to this schematic I'm posting.

4.7k sounds good. It was 10k in the first schematic posted (the Windsor schem with changes).

4.7k to ground and R47 = 100k ohms are similar to the Aiken example values, assuming the white OPT tap is around 8 ohms, and assuming all those values are correct. Removing NFB temporarily should show if I'm on the right track or not

[Captain chunkulus]

Okay, so I removed the -feed back resister, no change. I have to crank it up to about 9 out if a possible 12 to get a decent in room playing by myself volume.

[Captain chunkulus]

There is also, no difference in the sound with the -feedback hooked up or not. Sounds the same either way.

[Captain chunkulus]

Never mind,lol. I'm kinda embarrassed now but I found  the problem. Had the 2nd half of the phase inverter where the 1 Meg is wired to the bottom of the 1 Meg. So, the 2nd half of the tube wasn't working right. Ugg. Thanks for all your help.