5e6 Bassman alt schematic?

[maxkracht]

Does anyone know if there are alternate 5e6 schematics? This one doesn't seem to match the one I have, tone stack is different. Am I missing something?

[martin manning]

5E6 and 5E6-A have different tone controls.

[maxkracht]

Thanks Martin, I already checked the other bassman versions from the era. This one has an fmv tone stack. fixed 6k8 mid resistor, 100k slope, a 47pf cap, .02, and can't see the bass cap but I'm guessing .1uf.

[martin manning]

Interesting. Sounds like a step in the 5F6 direction.

[maxkracht]

That's what I was thinking, though I would have assumed 5E6As would have the transitional circuitry. Maybe I'm thinking too linearly.

[martin manning]

That's what I was thinking, though I would have assumed 5E6As would have the transitional circuitry. Maybe I'm thinking too linearly.

They were evolving continuously. I'd guess the -A was considered an improvement over its predecessor, since it became a production release. Yours might be a transition or prototype model going beyond the -A. Sounds like it has something approaching the AB763 Deluxe Reverb stack in topology. Can you confirm the circuit and cap values? 47p seems too small. 470p maybe?

[maxkracht]

I only peeked at the cap and saw a 47. Does seem overly small. Waiting on the go-ahead from the amp's owner before I dig in and get a proper look. Will trace the circuit and post a schematic.

[maxkracht]

Indeed, 50pf. Bass and middle caps are flipped from what I was expecting.

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[maxkracht]

Closer inspection, the bass pot and channel 1 volume are from the 60's. So, maybe ahead of its time, maybe someone's weird mod. Certainly has the right amount of patina to be original...

[maxkracht]

Does anyone have tips to gauge originality? Not all of the solder joints have the mounded up blobs like you usually see in tweeds, but that's not too unusual. Hard to tell the difference between a 70 year old solder joint and a 60 year old solder joint... I guess if I try to pull a component and it's bent around the back it has probably always been there. If it were a standard 5e6 it wouldn't have as many .02uf astrons. Waiting on some fancy red caps to come in the mail before starting repairs.

[maxkracht]

As far as I can tell, that section of the board was original. Slope resistor wrapped around the board and caps did a bit too.