Silvertone 4754 amp

[Rhodesplyr]

People who know I work on tube amps sometimes just hand me things, and this time, it was a Silvertone 4754 amp, apparently from a long-gone Silvertone organ. From what I can tell, most of these Silvertone 47__ amps were the same: 6CA4, 2 x 6GK6, 12AT7, 12AX7, obviously easy to convert for guitar use. I suppose there were minor differences from unit to unit.

I've seen a few past threads from others who've run across different iterations of this amp, and I was wondering if anyone completed a conversion. I've seen larger output transformers on 2 x EL84 amps and wondered how this one performed.

[RWood]

I did a 4732, which has the same tube lineup as yours. I believe it was built by Thomas, and it is the same as their AR-1 (from around 1963).

I built mine like a Marshall 18 watt Lite IIb, except I made the input tube switchable between parallel triodes and cascaded with gain control. It came out really well.

As an organ amp mine was originally fixed bias and there is a bias tap on the PT. I've been meaning to try it out but never got around to it. I used the traditional cathode bias on the 18 watt.


RWood

[RWood]

Here's a thread on that amp


RWood

[Rhodesplyr]

Thanks for the information. Thinking about the connection of Thomas Organ to both the Vox and Silvertone brands, I wonder how similar these are in terms of power and output transformers to the tube version of the Thomas Vox Pacemaker. The transformer numbers aren't exactly the same as the ones on the only Pacemaker schematic that seems to be floating around, but the overall similarities are striking.

Silvertone 4754:

OPT: 80-5031-1 (606/Schumacher, 46th week of 1963)
PT: 80-5018-6 (606/Schumacher, 49th week of 1963)

Vox Pacemaker (reported):

OPT: 80-5047-6 (606/Schumacher, 46th week of 1965)
PT: 80-5045-1 (606/Schumacher, 9th week of 1966)

I wonder if Schumacher still has transformer specs on these.

[T3chm@n]

Hey guys,
I just picked up one of the Thomas A-1 amps and it works fine.
It has the same transformers as the Silvertone:
OPT: 80-5031-1
PT: 80-5018-6
But mine are 36th week of 1962

However I noticed the amp has a live chassis (I'm getting 160vac from chassis ground to ground on my power strip)
I also noticed the actual chassis is "floated" with rubber grommets.

This amp has 3 sets of center tapped secondary transformer windings.
One for 6CA4 rectifier
one for the tube filaments
one for the some external device (goes thru 2 diodes)

I'd need to find a schematic as the Vox Pacemaker is somewhat similar but not close enough.
This amp also has 4 40mfd 15V non polarized caps. Not my specialty.

Does anyone have either a schematic for the Thomas A-1 or the Sears Silvertone 4732 or 4754 amp?
The thread RWood posted is dead.

Thanks,

T3chm@n