hummm issues

[Leif H]

If the output wires are green & black, you don't need the yellow wire. The jacks ground through the chassis connection. You are most likely causing a ground loop hum.

I am confused by your output jack wiring, it doesn't match the Weber layout & the Fender layout has no detail in this respect (you would be very lucky to build a properly functioning amp based purely on Fender schems & layouts, they are service documents, not detailed "how to" instructions).

According to the Weber layout, with the upright tip contact of the jack socket farthest from you (as they appear in your photo), the terminal to the LH side of the main speaker jack (Tip) gets the green wire from the OT, this wire is then continued to the ext jack tip terminal. The terminal farthest to the RHS (sleeve) gets the black wire & a jumper to the middle terminal (switch) on the main speaker jack. DOUBLE CHECK this, the sleeve/ground terminal is easy to spot because you can normally physically see the terminal connecting to the centre ring of the jack.

originally, I did not have the speaker jacks grounded, only though the chassis, I thought this was point, that I can remove.

The Output transformer green wire goes to the right jack, and jumps to the left (green jumper) the black wire goes to the left jack, and jumps to the right (bare wire) the left jack is switched to ground.

I possibly have a tripple ground loop there then... I'll go back and try as you have it explained above.

Now that we are on the grounding the jacks, should the input jacks just be grounded through the chassis not the ground lug on the sleeve?

I may try that as well... unless that's a no no.

[MWJB]

"... I'll go back and try as you have it explained above." Look again at the Weber layout..I stress again, identify the grounded (sleeve) terminal first, just in cas your jack sockets don't match the standard pattern.

From what I can establish at the moment your jacks only work because you have the green wire going to the switch (usually the centre terminal).

The input jacks also ground through the chassis, no additional ground connection is required, other than the tie point for you buss wire from the pots & preamp cathodes.

[Leif H]

"... I'll go back and try as you have it explained above." Look again at the Weber layout..I stress again, identify the grounded (sleeve) terminal first, just in cas your jack sockets don't match the standard pattern.

From what I can establish at the moment your jacks only work because you have the green wire going to the switch (usually the centre terminal).

The input jacks also ground through the chassis, no additional ground connection is required, other than the tie point for you buss wire from the pots & preamp cathodes.

My jacks are different than Weber's, and IIRC both jacks may not be the same, the pin out could be different, it's what I had on hand from years gone by and what was left of the FilmOsound.

Thanks, I think I may have several ground loops going on here, which would explain the hum... hopefully tonignt, I have practice volume above the hum.

[Leif H]

I checked the output jacks wiring and removed the ground jumper. I still had hum.

I removed the ground wire that I had going from each input jack to leave it grounding from the sleeve to the chassis, wired the volume pot's ground to the ground terminal of input jack one.

Still humming along.

I guess the next step is putting V1 and V2 cathode resistors / bypass cap grounds to the input 1 ground terminal and tidying up the heater wiring and finally putting the virtual centre tap on the heater wires.

What wattage should I use for the 100R resistors, 1/4 1/2 or 1 watt resistors?

[MWJB]

The 2x100ohm virtual centre tap should have been your first job...without it you will always have hum. 1/2W resistors.

Don't waste time by revising the grounding scheme "piecemeal", do the whole job as previously described.

[txstrat]

I moved the grounds from the brass plate, to a star ground as follows;
Bias, 1st & filter caps have a shared ground
Thoughts?

I'd separate the bias cap ground from the main filter caps ground, since this can induce hum directly into the grids of the power tubes.
+ take care that the heater wires of the preamp tubes go to the same lugs. Pin 9 to pin 9 and pins 4/5 to pins 4/5.

[MWJB]

Preamp filter cap wants to be grounded with preamp cathodes @ input jack, not with main & screen supply caps.

[Leif H]

By filter cap, I assume the bypass caps on the cathode resistors?

and bringing these wires up to the input's wont that cause noise? do I keep them tight to the chassis?

I'm rummaging all round the net looking for images of wired chassis, and having a hard time finding how these wires are routed.

My first order is to get the virtual center tap as you said earlier, and tidy the heater wires.

Lets hope that does it.

[Leif H]

The 2x100ohm virtual centre tap should have been your first job...without it you will always have hum. 1/2W resistors.

Don't waste time by revising the grounding scheme "piecemeal", do the whole job as previously described.

Last night when I got home I didn't have any 100R resistors... I swore I grabbed some, but there were four 470R for the screens on the output tubes. I guess I left them on the counter and picked up the wrong ones.

[txstrat]

By filter cap, I assume the bypass caps on the cathode resistors?

Filter caps filter the ripple out of the B+ voltage.
Bypass caps bypass some current alongside the cathode resistor.
Coupling caps decouple the DC of a plate from the next grid while they let the signal (AC) through.

and bringing these wires up to the input's wont that cause noise? do I keep them tight to the chassis?

I usually have my B+ wires floating above the circuit components.
Ground wires can be close to the chassis. Works for me.

[Leif H]

Thanks guys!

It's rockin' now!

It's as quiet as it should be.

Just like to thank you all for helping me with this, It's much appreciated!!

Now... what to do next?

[thehoj]

Thanks guys!

It's rockin' now!

It's as quiet as it should be.

Just like to thank you all for helping me with this, It's much appreciated!!

Now... what to do next?

So what ended up being the biggest reduction in hum?

Was it grounding the preamp cathodes with their respective filter cap? Should the bypass cap for that cathode also be grounded at that same point?

[MWJB]

"Should the bypass cap for that cathode also be grounded at that same point?" cathode resistor & bypass cap can share a ground wire, but it's best to have the cathode resistor & cap of any following stages with their own wire to the preamp ground point. In-phase cathodes, of the same tube (e.g. if you gave each half of V1 its own cap & resistor in a 5E3/5F6A type circuit) can share a wire too.

[Leif H]

I think the largest culprit was not having the center tap or virtual center tap on the heater wires.

[thehoj]

I think the largest culprit was not having the center tap or virtual center tap on the heater wires.

Maybe I missed what state this was in before hand. Was it not grounded at all?