Fender Tweed Pro Owners

[Fletcher Munson]

I'm looking for some detailed pictures of 1953 to 1954 Pro amps (models 5C5 and 5D5). If you have (or can take) any gut shots, I'd like to see them. I'm looking to build a reproduction of what you might call the "5C5-1/2" model. In late 1953 or early '54, Fender converted the 5C5 from 6SC7 to 12AY7 preamp tubes. I'd like to see how they wired the inputs. Also curious about the lead dress and whether they modified the chassis or simply put in adapter plates to accommodate the noval tube sockets. If you've got a Pro amp from this time period, and you're willing to share, please let me know.

[Enzo]

Maybe this helps? Both have layouts

http://bmamps.com/Schematics/fender/pro_5d5_schem.pdf

http://bmamps.com/Schematics/fender/pro_5c5_schem.pdf

[Fletcher Munson]

Thanks. I’m familiar with those. I should explain that my question is more historical than technical. I know how I’d do the conversion, but I’m more interested in seeing how Fender did it. I’ve found pictures of 5C5 tube charts where “6SC7” is crossed out and “12AY7” written in. Maybe one of the owners did that but, given Fender’s well documented frugality, it’s quite possible that it came that way from the factory. Knowing that, I’d like to see how they did this conversion. Did they produce a new circuit board, or just modify the existing one? New chassis or modified? I know a lot of people find this kind of thing boring, but I don’t and I’m hoping someone out there has an example of one of these amps that I can document.

[Enzo]

Yes, Fender many times used tube chart stickers that were either altered or just didn;t match.

I can;t answer your questions. I have seen various fender chassis with cover plates for unused holes. Example one chassis might be used for models with rectifier tube and others without. But I have never sen a cover plate with a socket in it. Doesn;t mean they don;t exist, but I;ve never seen it.

According to the schematic, the 5C5 was the conversion, there are notes on the schematic and layout. Apparently both tube types were wired as grid leak. By the 5D5 it was changed to common cathode bias. The layout clearly shows the part board is different, if nothing else, all those large input caps were eliminated when the grid leak left. I have no guarantee, but on the 5c5 there would be no reason to change the part board. Change would just be the tube sockets.

[Fletcher Munson]

Yes, I think you’re right. They probably continued to use grid leak bias when they converted from 6SC7 to 12AY7. Therefore, no changes to the circuit board or inputs. All they had to do was re-route the wires to the sockets. They still needed to modify or replace the chassis, though. Thanks for you observations there.