No output from new amp build

[Bootsman]

12xxx Marshall build help

[thetragichero]

more information needed

[Bootsman]

I when I turn the amp on I can hear it when it turns on but when I have my guitar plugged in all I can get is the sound of the amp running and if I turn all the knobs I can hear scratching sound only from the presence pot all my voltages are good except on three pins on v2 it’s a 12xxx. Marshall build

[thetragichero]

pictures? schematic? what are your voltage readings? i've never heard of a marshall 12xxx. the more information you provide the better chance you have of receiving helpful suggestions

[Colossal]

I've never heard of a marshall 12xxx.

This is a replica of the '68 Superlead 12,000 serial number amps, with Van Halen's being 12301 (pretty sure...but maybe Roe will correct). Laydown PT and low filtration. Chewy good!

[Bootsman]

Yes it is I was able to get most of the voltages pretty good except in v2

[Colossal]

Yes it is I was able to get most of the voltages pretty good except in v2

Please post a high-resolution gut shot of your amp and a table of voltages. It should look like:

Example:

Power transformer AC secondary 350VAC
Rectified DC at [your mains AC voltage here]VDC
B+1 460VDC
B+2 (after choke) 457V
B+3 360V
B+4 330V
B+5 310V

V1 Plate 140V
V1 Cathode 1.05V

etc...

These are the basic minimum requirements needed for us to be able to provide some direction.

[Bootsman]

V1
Pin 1 210v
Pin 0v
Pin 3 1.24v
Pin 4 3.06v
Pin 5 3.05v
Pin 6 274v
Pin 7 0v
Pin 8 2.29v
Pin 9 3.10v
V2 pin 1 105.6v
Pin 2 .004v
Pin 3 418.8v
Pin 4 3.10v
Pin 5 3.10v
Pin 6 108.6v
Pin 7 108.7v
Pin 8 108.5v
Pin 9 3.1v
V3
Pin 1 269v
Pin 2 29v
Pin 3 47.8v
Pin 4 3.11v
Pin 5 3.11v
Pin 6 266v
Pin 7 31..5v
Pin 8 47v
Pin 9 3.05v

[Colossal]

V2 pin 1 105.6v
Pin 2 .004v
Pin 3 418.8v
Pin 4 3.10v
Pin 5 3.10v
Pin 6 108.6v
Pin 7 108.7v
Pin 8 108.5v
Pin 9 3.1v

[Bootsman]

[pompeiisneaks]

What he's saying is those voltages are 'really' wrong.

Pin 1 is the anode and should be maybe 300 or so volts, its' 100, Pin 3 is the cathode and should be tens of volts except in a cathode follower but even then significantly LOWER than the anode voltage. Something's wired wrong in the amp.

also pins 6/7/8 all being 108 volts seems really odd... Without a schematic, though I'm just guessing, but they should be similar to V1.

~Phil

[Bootsman]

This the layout I have https://diyguitaramp.tistory.com/m/311

[pompeiisneaks]

You may want to delete your screenshot and re-upload without the extra adult themed tabs there... Also it's best if you can just give a link to the site with the layout and a schematic would be great...

Also, that shows that a high voltage connection off a dropper resistor that goes to the pin 6, which then goes through a dropper resistor to pin 1... both should be in the 300+ VDC range, you're showing 100. Pins 3 and 8 both connect to ground so they should be lower voltage... as I stated. Somethings wired wrong for sure.

I would suggest photos of the amp might help here as well. Are you following a schematic? Do you know how to read one?

~Phil

[Bootsman]

I got it working now

[Colossal]

also pins 6/7/8 all being 108 volts seems really odd... Without a schematic, though I'm just guessing, but they should be similar to V1.

~Phil

Cathode follower