Kay 703 head scratcher

[Structo]

I'm not sure what you mean.

The schematic shows an isolation transformer.

Are you saying it isn't a 1:1 transformer?

I see a newer transformer inside the amp, and there is a little one there as well that looks old.

What are these trannies?

[bradb]

i see what youre seeing in the schematic.

But,
i think that power plug current is still passing thru the chassis. see the heater circuit.

I think a 1:1 transformer is needed at the plug, such that the chassis can be earth grounded.

[Structo]

Hmmm, I'm not sure if you added another 1:1 trannie that you could ground the chassis since you still have the possiblity of having voltage on it.

A truly puzzling amp.

What are the two trannies you have in there now?

[M Fowler]

Not sure if this will help but this is how to convert the All American four for safe play.

Mark

[bradb]

That does help. Thats exactly what I was thinking.

I've been having trouble wrapping my head around why the isolation transformer will work.

Currently I have the chassis grounded, this in, effect shorts one of the prongs (hot or neutral depending on wiring) to ground causing the amp not to function.

the isolation transformer allows you to "float" the 115V and reference one of the secondaries to ground, without having a short from hot or neutral to ground.

[MartyT]

Hi, I came across this post on a google search. I recently bought a Kay 703 in SUPERB (like new) condition. I have determined it is not a C model, but the original 1963 703. I love the way the amp sounds, but after receiving quite a shock last night after playing through it, I started researching what I now know is dubbed a "widowmaker" of an amp...ouch! I know very little of amp/electric stuff, but have shared what I learned through this post and others with a fellow electrician, who says he can make it safe with $75 labor + parts.

My question is: is it worth it to make the mods to this cool little amp to make it safe to play through, or is it more "collectable" if I leave it deadly and not play through it? In which case, I'd probably repost on Ebay...your thoughts??? Much appreciated!!!