Hoffman Amplifiers Tube Amplifier Forum

Amp Stuff => Tube Amp Building - Tweaks - Repairs => Topic started by: TIMBO on October 16, 2021, 08:56:47 pm

Title: Marshall VS100 Power Transformer Repurpose
Post by: TIMBO on October 16, 2021, 08:56:47 pm

Hi guys, Got a a dead VS100 combo.
I think the PT could be used for the HT supply.
Anyone have any idea of current capacity.
Thanks
Marshall_marshall_vs100_2.pdf (el34world.com) (https://el34world.com/charts/Schematics/files/Marshall/Marshall_marshall_vs100_2.pdf)
Marshall_marshall_vs100_3.pdf (el34world.com (https://el34world.com/charts/Schematics/files/Marshall/Marshall_marshall_vs100_3.pdf))

Title: Re: Marshall VS100 Power Transformer Repurpose
Post by: PRR on October 16, 2021, 09:01:27 pm

Is that the whole thing? One small tube and some small chips? Or is there more?

Title: Re: Marshall VS100 Power Transformer Repurpose
Post by: TIMBO on October 16, 2021, 09:28:41 pm

Hi PRR,
I'm only guessing here..
The supply to the 12ax7 is 240ac and is about 340v rectified.
It has a 250mA fuse, so I would think it could be good to supply 3-4 12ax7s
The supply to the main amp is is a 64v CT, put this through a quadurpler could supply approx. 330v but the current is unknown.
It has a .5w fusible resistor, if that is a clue.
Heaters would be supplied via a separate PT
The heater supply would be good for one tube, has a fuse of 250ma

Title: Re: Marshall VS100 Power Transformer Repurpose
Post by: PRR on October 17, 2021, 12:04:03 pm

It will heat one small tube wired at 12V.

The power amp ate 88VDC @ 1.8A DC, so say 350V 450mA. A 12-pack of 6V6??