while it may be a general "rule of thumb" some Gibson GSS had the "B" series of circuits
I believe that only the "B" version had the "Rock & Roll" switch on the front which makes that a pretty good indicator.
This switch bypasses the Tremolo/Vibration board, but like a pedal it isn't a true bypass, only the outputs of the Treble preamp and the Vibrato board are switched
I have a GSS-100 which has the "B" boards
It is very similar in design the American Thompson VOX Beatle amp (114/1141) amplifier of the same era.
On the Geofex web page there is a lot of information about fixing the output amp of the Beatle which is an interstage/totem pole amp as well.
I would go ahead and replace the Power Amp resistors and the bias trimmers.  I've had go luck with several Thompson VOX amps by adding precisions resistors and new transistor sockets

I have a GSS100 that has had a complete cap and resistor update
Overall it works fine but has a couple of issues.
1 - Persistent hum.  May be just part of the design after I added a 3 prong AC cord.  Worse with Reverb turned up
I was thinking of adding isolated Input jacks and having a dedicated signal ground.
2 - "spitting" noise - random from the system.  No specific control or cause. Appears to be from the power amp since it occurs with either pre-amp chain.  The main Power Supply caps are new as are the ones
3 - Pops - loud., But it seems to be only with the "Rock - n - Roll" switch in the Off position.  Turning the Tremolo knob from Vibrato to Tremolo creates a very large pop.  Turning the amp off/on creates a typical "solid-state" pop.  But none of this occurs if the RnR switch is On.  It seems like there is a ground issue or "floating" voltage when the Vibrato Board is cut out of the signal path.
I've attached the schematics of the affected boards - I have the "B" model set.
Any ideas would be helpful.

I understand about the idea that a lot of things can cause hum but I just was wondering sing the whole idea of the polarity switch and the "death cap" was to ground the side that produced the least amount of hum.
Wiring an older amp with a new 3-wire cord, and using the standard wiring code, it might not connect the amp hot & neutral up to the side that hummed the least.

I've never tried swapping the black & white wires to see if that changes anything.
I also can't tell what, if any, effect that the use of a driver transformer has on the overall rejection of hum.
It is the Epiphone that floors me.  When I got it, it was working, sort of, but there was no real appreciable hum.
The whole front panel and chassis seemed to be the ground plane.  Every ground was haphazardly connected to the nearest point, i.e. Cathode resistors to the back of a volume control, Pre-amp B+ capacitor and cathode resistor grounded together, etc.  Just about every "bad" layout connection you could name.
Added the 3-wire grounded AC line and there is now hum in the system.

It is next on my schedule so I will take another look at the wiring.
Michael

Update - It's working
The 2 10" speakers sound good
The bass/treble pots are shot - will have to figure out a replacement
I think the board was also used in the Polytone 412 amp.  The empty sockets and circuitry in the Mini V layout, appear to e for the Tremolo circuit.  Although there is a heck of a lot of other unpopulated real estate, I've seen models with two "stacked" controls in the center as well.  I was probably the same 2-channel board for all.

With my archtop you can hear why these amps enjoyed their reputation.  Nothing special in the design, but well built and not stressed.

The diode is "stuck" to the tab of the TO220 with silicon "paste"
I looked for a clamp - like you see in some of the SWTP "Tiger" amps but no luck
Right now it is working, "don't fix it if it ain't broke"
The amp was obviously worked on - there's a note for 2010
Would like to see - just for giggles - what the board looked like originally.  I suspect there was some form of clamp on the driver for the diode.
I'm finishing up the cabinet work so I hope to post a picture later

Thanks for the information
There were just a couple of things that appeared to have been changed when the amp was serviced - and I've not been ale to get an interior shot of this version
I'd like to see how the bias diode was originally thermally connected to the driver transistor
I admit to being a bit OCD about having all of the information.
Just finished a cleaning and cap update - new transistor sockets and insulators.  All the power transistors were TRW's
With 100 watts RMS into 4 ohms, there is a lot of weight to the sound, and it takes modulation pedals great.
Another interesting find for the collection

Michael

Sears Service Manual - Model Number 257.14313201
"slant face" design
I've attached the schematic and parts list
Only the STB567 is a standard part number for the bias diode
Only two Sears numbers crossed to an NTE
128-9050 = NTE 130 NPN T03 Outputs
126-1 = NTE 156 diode
Nothing on the rest of the semiconductors - although I suspect they are standard types for the circuit.
On my unit it appears that Q9 and Q6 have been replaced.
Just wish there was a Sears to normal cross reference for transistors

Interesting schematic - the preamp is about as simple as you can get, even for a bass preamp.
The output amp is much more sophisticated than many contemporaries, Harman Kardon, VOX, Standel all were using transistor drivers for their outputs well into the 70's
Solid design - 100 Watts RMS using 4 outputs 37 rails is pretty conservative.

Usually attached to its own ground point, or to a lug on the power transformer
I'm sure it's 60 cycle

Michael

It may be coincidental but a couple of the restored guitar amps I've done seemed to have an issue with running a 3-wire AC cord with ground and removing the polarity switch circuit.
The latest is a Gibson GSS100 head that has a more pronounced hum after a cord and capacitor replacement.
I've had the same issue with a Vox Berkeley 3 head and a Fender 1st generation solid state Deluxe Reverb
The amps have the same type of transformer driven "totem pole" output circuit. Could it be that this type has an issue with the hard chassis ground with the 3-wire AC cord?

A very frustrating issue as I haven't added/removed any of the circuit grounds, the inter-board wiring was the same.
Thanks
Michael

Not sure what the Silvertone part number would be as I don't think this version was a Silvertone design.
The last Silvertone designs all had driver transformers and  "totem pole" output stages like those of the Thomas Vox and Standel guitar amps.
I wasn't going to change any as it works, but the driver transistors appear to be replacements TIP 32A/31A.  The biasing diode is thermally connected to one but with the change I'd like to make sure the diode is connected correctly.
And to just add to it - the thermal bias diode is a STB567 -Stabistor diode.

The output circuit is very similar to the original RCA 70 watt amp "Quasi-Complementary" design, and the Kustom amps of the "tuck & roll" era.
Michael

I have a really nice, working, 2nd version Sears/Silvertone 200BLX head.
It has been upgraded once (caps) and sounds great
This is the later version with a more modern power amp - no driver transformer - looks like a Hafler or Kustom amp

The service manual lists all the parts with a Sears part number, no a problem with the passive parts, but no idea what the original devices were.  The driver transistors appear to be TIP devices (220 case) and not original.

Any place to find a cross reference for Sears transistor part numbers?
Thanks
Michae