Mark 1 reissue filament grounding ..

[jedmon01]

I've just noticed that the export version of the Mark 1 reissue has the CT of the heater winding grounded.
But it also has the two 100ohm grounding resistors as used on the non CT domestic mains tranny.
Will this double grounding be a problem ?

I am just fitting a 240V export mains tranny to a 117V Boogie and want to know the best way to wire it.
i.e.
Ground the 6.3V CT
Leave the two 100ohm grounding resistors
do both ?

John

 

[shytfayse]

If your export transformer has the same center tap on the 6.3VAC winding as the North American one, just keep it the same.

 

[jedmon01]

Hi,
My current 117V mains transformer has no CT on the CT winding, hence the two 100ohm resistors to ground the filament cct.
The transformer I am about to fit HAS got CT.
Are you suggesting I connect the CT to ground in addition to the grounding resistors ?
Many Thanks
John

 

[Boogiebabies]

If the filament tap has no center tap, use two 100 Ohm resistors for ground reference.
If you don't, you will more than likely have well above 6.3V in the 15+V range. IIRC on the last Fender PT I was working on, without ground reference I was at 22V.

 

[shytfayse]

You can either remove the 100 ohm resistors (the artificial center tap) and ground the center tap, or, cap off the center tap and leave the 100 ohm resistors in.

Good luck. Pat.

 

[jedmon01]

Hi Pat,
Many thanks.
I'll take your advice and not connect the CT, leaving the 100ohms to do the grounding.

Cheers
John

 

[jedmon01]

Decided to go with the 6.3V CT grounded, and removal of the two 100ohm resistors.
Very slight hum in a quiet room with master on "0", but no problem at a gig.
Strangely when the master is turned to "3" the hum almost goes.
Not sure why this is ?

John