Gibson not sure of model - schematic

[pontiacpete]

Can anyone identify this old Gibson? Tubes are: 3 x 6c5, 4 x 50L6 and 4 x 25Z5
field coil speaker. The 2 wires that are unhooked in the picture, I don’t know where these go.
No sound. Tubes light but no DC voltages found so far.

[mozz]

Similar to a EH-160? EH-150?
https://www.superiormusic.com/page199.htm
https://www.gibson-prewar.com/gibson...er-3rd-series/


Be sure somebody didn't just stick tubes in there.

[pontiacpete]

It’s looking a lot like the eh 160, except for the 50l6s. I’ll have to check if they can be swapped in for the 25B6s

[mozz]

Could have been rewired due to availability of the tubes. Factory or DIY.

[pontiacpete]

Looks like a 25B6 is a pentode and has the same pin out as the 50L6
I’m still not getting DC voltages on the 25Z5s

[g1]

and 4 x 25Z5

Is this a typo? It's not really a Quadruple Rectifier is it? Mesa would be furious.

[pontiacpete]

It really is, can you believe it?

[g1]

I see now, and am attaching EH-160 schematic, even though power tubes are a bit different. I think they will just be arranging the power tube heaters in 2 parallel sets, rather than all 4 in series like the schematic shows.
Are rectifier tubes lit up?

[Helmholtz]

So another widowmaker.
Be extremely careful!
Only connect via a large isolation transformer and connect the chassis to safety ground.

[mozz]

Wow, for 220v operation, add the 100w resistor!

[Chuck H]

So another widowmaker.
Be extremely careful!
Only connect via a large isolation transformer and connect the chassis to safety ground.

Not just a widowmaker... A four output tube/four rectifier tube push/pull circuit widowmaker. I guess I shoud be be more familiar with the old Gibson amps but this is a first for me. Yeech!

[Justin Thomas]

It's not really a Quadruple Rectifier is it? Mesa would be furious.

You should jump the gun on them & file the TM now before they get the idea.

Jusrin

[Chuck H]

Not just a widowmaker... A four output tube/four rectifier tube push/pull circuit widowmaker. I guess I shoud be be more familiar with the old Gibson amps but this is a first for me. Yeech!

This plus a field coil speaker with HV terminals outside the chassis. Imagine trying to market this design today !!!

"Well sure a few stupid or careless people are going to die from electrocution but there's a public demand for what this unit does." And the powers at the time said "Okay then."

[pontiacpete]

So I’m not getting any signs of DC anywhere. There’s 120vac on the rectifiers but nothing on their cathodes. With no way of testing the 25z5s and none in my tube stock, I think I should just pass on this one.

[Helmholtz]

There’s 120vac on the rectifiers but nothing on their cathodes.

Are they heating?