Fender DeLuxe Vintage Modified OPT Teardown

6L6GT  push pull amp is making this weird on again off again sound that is not unlike what you would hear seconds before a power line transformer erupts into a blue flash and a thunderous roar,
which actually happened last night as i was walking home but that is another story,

can not figure it out, as soon as you remove the chassis it goes away,  pull the phase inverter tube and it keeps going,
process of elimination now, 

so we tear into the output, which is a Shumacher  (EIA code 606)

layered paper job done, so we have a wood wedge to keep the coil tight on the core,

100 EI  (1" tongue)  like a 6L6GT Pro Reverb,  with a healthy 1 - 3/8" stack, so a definite upgrade as far as power handling capacity,

circuit where used...

all leads done on the same side, would like to see the HV on one side and speaker leads on the other, JIC.

if you remove the blocking wedge then you have room to work the lams free,

usually requires a re-heat  to get the last ones out without damage,

staggered leads taped down with filament tape,  heavy poly lead plate and one on top,

simple primary-secondary-primary coil, taking off the last outside primary layer, 1 layer of 10 mil poly and 1 layer of  probably 1.5 mil KP on top of that for pri-sec insl.

pretty good winding job on this guy, but the wire felt real cheap, and the first turn coming off the blu lead broke during unwind, so maybe a nick in the wire or deformity which causes a neckdown of the diameter which can lead to intermittent contact,

single layer secondary wind of 28 turns,

let's see if they followed the root 2 rule fore doubling impedance,

turns ratio is root of impedance ratio, 8 to 4 ohms is a Z ratio of 2;1,

so turns ratio will be root 2/1 = 1.414

zero to 4 ohm wind was 68 turns,    root 2 time 69 = 1.414 x 68 = 96.15 T for 8 ohms,

96 - 68 = 28 T for the 4 to 8 ohm tap, , perfect.

so Fender is sticking with pretty much the same transformer as used in the Pro Reverb and Bandmaster,

100 EI core, 4K load ration, only with a fatter stack (up from 7/8" to 1  3/8")

nice sounding amp with built in DSP effects and a Celestion speaker.

hopefully a rewind with better wire will cure the weird sound,  if not, then it is the pwr xfmr, 

print>