Low volume in preamp stage

[Realist2]

The 470 ohm resistors I installed in the other amp "69", were on the screens. (Pin 4)
The 470K's are as schematic in that one as well as this "71"

[Realist2]

[Pedro Vecino]

The pin four is the red wire, attached directly to pin four of the other tube. No screen grid resistors here.

[Realist2]

No screen resistors in this one"71". I added the screen resistors in the 69, and I just noticed that I added them in the "edited" schematic.

[Realist2]

Here's the URL to the original unedited schematic.

http://schematicheaven.net/bargainbi..._gvc-9056a.pdf

[g1]

The 470K resistors from pin5 to ground are getting confused with the screen resistors. Pin5 is control grid, pin4 is screen grid.
The edited schematic is wrong. The resistors at pin4 of the power tubes should be 470ohm, not 470K.
As you stated in post #31, the resistors you installed in the '69 were 470 ohm, not 470K.
The ones you measured in post #28 are at pin5, not pin4, and are not screen resistors.

So there is no problem, just a typo in your edited schematic.

[Realist2]

Yes sir, those are 470's not 470K, I never realized that those were the ones in question, or that they were on this edited schematic. Sorry that was my typo. Actually those aren't originally in the amp or schematics.

[g1]

Ok, that makes a lot more sense now.
Now, since you added the bypass caps to the triode stages, I think the gain has improved?
But you should still try replacing the 150K's at V1A and V2A with 1 or 2 meg resistors. It should make a big difference.

[Realist2]

Hello G1, yes channel one sounds good, and loud, but channel 2 was motor boating with volume 7+.
Do I need the .05's at the input? My Fenders don't have them?

[g1]

You don't need them and can remove them.

[Tom Phillips]

You don't need them and can remove them.

That is..."replace them with a wire."

[Realist2]

After adding bypass caps to the preamp, the fifty watts of volume returned. It bothered me though that I had to modify the amp to make it work. I'm pretty sure Montgomery Ward, wasn't selling 50 watt amps that could be drown out with by a 5 watt Epiphone.?

The next issue was motor boating on Ch2 at volume 7+. I could stop the motor boating with wire dressing, at one of the Ch2 circuit boards. I redressed all the solder joints there, but the channel was still thin and distorted. So I removed that board from the amp refurbished and reinstalled it.
While I had it apart I replaced the .05 input cap, with a wire, and replaced the 150K, with a 1m ohm. I replaced the .05 feeding the tone stack, with an .047/ 600 .

Finaly, I've got plenty of volume in both channels. I'll attempt a description;
Channel one, (stock w150K) Brown, bassy, but with a nice shimmer. Jazzy with nice chimes.
Channel two (with the 1m ohm) Bright and articulate, but will get sassy when you push the volume.

Thanks all.