Fender Bassman 100 rebuild

[Mark]

Hi Phil, I'm certainly not getting amazing service. I wanted to know the size of a filter board he makes and have received no reply, Doug says the size is specified on his site, but I haven't been able find it. The rectifier board is smaller than the width of 3.125 and I wanted to know if he could cut it down. I don't think so,

He sent me this link:

https://hoffmanamps.com/MyStore/catalog/EyeletBoard.htm

If you can see the sizes I'd be much obliged.

[pompeiisneaks]

On that page he says the size of his boards are all 3.125 on the one dimension, that's a static figure he can't change, I think due to how his jig is setup for his cnc machine or something similar.

He shows on each board, the length, so if you chose the the fender filter cap board with 5 caps it says it is 5.5 inches so your dimensions would be 5.5 x 3.125

Does that make sense?

Sorry he's not being forthcoming about it.

~Phil

[Mark]

I'm going to get a friend to help me out with the boards. I think that will end up with a better outcome. I'll post pictures as I progress.

[Mark]

I'm in the process of getting Garolite boards made for the amp. I dare it will take a while, but it will be good to get back to work on the amp.

[amidzadado]

Hi!

I'm in similar process of experimenting/restoring Bassman 100. Is there any schematics/advice how to put out master volume?

Damir

[Mark]

There are a few ways around it. You can use the Brownface 6G series PI and use a 25K presence pot, or use the 5F series PI which will have a bit of gain and use a 5K pot. The Tweed PI does have it's own sound, so it might not work if you want transparency.

I'll probably borrow from the Dumble circuit which uses a 2K pot. I'm thinking of sticking with the 47K plate resistors. I'm indecided on the output stage grid leak resistors.

https://ampgarage.com/forum/download/fi ... &mode=view

https://ampgarage.com/forum/download/fi ... &mode=view

[Mark]

The new boards have been made and they are on there way. The next thing is to decide what brand of caps to use.

IMG_1261.JPG

IMG_1262.JPG

[Mark]

Who makes good knobs for the silver face amps?

I only have four of the original knobs leave and they look pretty rugged.

I'll need the deep and bight switches too.

Any thoughts?

[martin manning]

https://www.tubesandmore.com/products/k ... -set-screw Generally a reliable source. You'll find slide switches there too.
https://www.tube-town.net/ttstore/fende ... black.html If shipping from Europe is more convenient.

[Charlie Wilson]

There are a few ways around it. You can use the Brownface 6G series PI and use a 25K presence pot, or use the 5F series PI which will have a bit of gain and use a 5K pot. The Tweed PI does have it's own sound, so it might not work if you want transparency.

I'll probably borrow from the Dumble circuit which uses a 2K pot. I'm thinking of sticking with the 47K plate resistors. I'm indecided on the output stage grid leak resistors.

https://ampgarage.com/forum/download/fi ... &mode=view

https://ampgarage.com/forum/download/fi ... &mode=view

100k grid leak for 47k.
CW

[Mark]

The amp rebuild has taken a bit on an unpleasant turn with the discovery that the output transformer is not the original output transformer.

The original output transformer has the number 021667 and it's obvious that it was larger than the current transformer which is a Schumaker 022889, which was used in Twin Reverb amps, or maybe even the blonde amps.

What to do next, what are your thoughts?

Thanks for your help.

EDIT: I have found out that output transformer 021657 is another Bassman 100 transformer.

IMG_1269.JPG

IMG_1268.JPG

[Zouto]

The amp rebuild has taken a bit on an unpleasant turn with the discovery that the output transformer is not the original output transformer.

The original output transformer has the number 021667 and it's obvious that it was larger than the current transformer which is a Schumaker 022889, which was used in Twin Reverb amps, or maybe even the blonde amps.

What to do next, what are your thoughts?

Thanks for your help.

EDIT: I have found out that output transformer 021657 is another Bassman 100 transformer.

IMG_1269.JPG

IMG_1268.JPG

You could use a https://www.hammfg.com/files/parts/pdf/290FX.pdf output transformer. I used it as replacement for blown OTs in several Bassmen 100 for best results, soundwise and mechanically.

[Mark]

Thanks for the reply, the link is to a power transformer. The core thickness of the 023889 is 1.5" wide, while TAD (Tube Amp Doctor) states the thickness of their repro transformer is 2" thick. The original transformer has quite a larger core. The problem with the TAD transformer is freight costs and the mounting holes don't line up with my amp, making me wonder how authentic it is.

[didit]

Try this link instead—https://www.hammfg.com/files/parts/pdf/1750WA.pdf.

[Zouto]

Yeah, this is the right link to the output transformer
https://www.hammfg.com/files/parts/pdf/1750WA.pdf