I don't understand this champ clone diagram... help me out?

[elkym]

http://i227.photobucket.com/albums/dd78/elkym/guitar/5F1ChampUniversal-Layout200.jpg

On the 6V6 pinout... why are the heater pins connected to the 8 pin through those 100 Ohm resistors? What does that do?

[phsyconoodler]

Because pin 8 is the cathode and it goes to ground after the cathode cap/resistor on the board.Connecting the heater center tap or virtual centre tap to the cathode is a common way with cathode biased amps to reduce hum.
The 100 ohm resistors form a 'virtual' centre tap,when you don't have one on the transformer.
Follow the yellow wire from pin 8 to the 470 ohm/22uf cap.Then the other end goes to ground.

[elkym]

aahh.... I get it. Thanks.

[ben-horn]

Hi,
would this "Heater Voltage Biasing" works in a 5E3 tweed deluxe,too ?
Does it significantly reduce the hum ?

thank you

[Ronsonic]

The beneficiary of that biased heater string is the preamp tube. With the heater held positive relative to the cathode it is less able to add noise. It's effect is additive. It won't hurt.

In some amps you'll see a voltage divider off the B+ to provide a + 40VDC supply for the purpose.

[tyru007]

This does help to reduce hum in a SE. I have the filament power connected in the same way as shown above. Lifted the wire off just to see and got a lot of hum.

[stratman_el84]

Hi,
would this "Heater Voltage Biasing" works in a 5E3 tweed deluxe,too ?
Does it significantly reduce the hum ?

thank you
Yes, it would. The problem is that, if the amp is built according to the original design (one heater lead daisy-chained to each tube, the other heater lead grounded), you'd need to lift the one heater lead from the PT going to ground and attach it to a terminal strip, then un-ground every tubes' grounded heater pin and run another heater lead back to the one that's been tied to the terminal strip.

Once both heater leads are 'floating', then you can put a 100-ohm resistor to ground from each heater lead. You can also use a 250 or 500 ohm linear potentiometer instead of the two 100-ohm resistors, tying the heater leads to each of the two outside-tabs of the pot, and attaching the wiper (center tab) to ground. This creates a 'hum balance' control which is found on many older tube amplifiers, especially those meant for PA and home-stereo use.

Cheers!

Strat

[elkym]

So what's with the connection between the 22k resistor and the 3.2 lug on the input selector...?

[s2amps]

So what's with the connection between the 22k resistor and the 3.2 lug on the input selector...?

That's the negative feedback resistor.

[elkym]

Is the wire coming from lug 3 of the 6V6 the B+? I really should buy a book about all this stuff...

[elkym]

anybody?

[Trout]

Is the wire coming from lug 3 of the 6V6 the B+? I really should buy a book about all this stuff...

Pin three is the Anode(plate) of the 6V6.

There are several places in the amp that are B+, but if you are looking for the in circuit plate voltage of the 6V6, that is a good place place to measure it.