Hiwatt with no sound

[fiesta55]

I just bought a hiwatt 50W lead model SG-50.Kind of an odd ball and I can't find a schematic for the preamp section.I have rebuilt the bias supply and put in a MM output transformer.All of the voltages seem to be fine in the power supply but I have no sound.Checking voltages in the preamp section they all look good with the exception of 1VDC on pin 1 of V2.
I get some signal thru the speakers when using a signal generator but none with a guitar plugged in.Any ideas?
TIA

[MWJB]

1VDC on a 12AX7 plate sounds like a bad thing, open plate resistor? Check value.

[fiesta55]

Thanks.It was an open plate load resistor.But I still have a problem.I'm not used to resistors with 4 color bands.The one I took out was Red,Red,Black ,Orange which I assumed was 220k.I replaced it with a 220k and now have a high frequency ocsillation.All of the preamp tube sockets are fairly microphonic.Did I use the wrong value?

[Mars Amp Repair]

I believe that your resistor would read 22.0 K ohms. The extra band (black or '0' in your example) allows a more refined value to be displayed on the resistor.

Though, I do agree that 220K seems more like what we're used to seeing in the plate position. glen

[fiesta55]

Can anyone confirm the 22.0k I found a resistor code calculator on line for a 4 and 5 band code and it says it would be 220k.

[Mars Amp Repair]

oh yeah...that's correct...I got the decimal in the wrong place...if it were red-red-brown-orange...it would be a 221K...sorry for error....glen

[Enzo]

220k.

Even if the 3-4 color band thing was confusing, you would not likely see a 22k plate load on a 12AX7 in a guitar amp, while 220k is perfectly reasonable.

A lot of newer resustors are close tolerance, so they added an extra digit band, which means the multiplier band would be one less. Thus 220k is 2-2-0-000, instead of 2-2-0000.