Point-to-point help

[Geezer]

I've had a blue board and SCA-35 iron at hand for a few months but I haven't found the time to make a chassis--it'll happen, I just don't know when (my apologies to Shannon). But somebody upstairs must be trying to tell me something, because I just tripped across another half-finished ST-35 clone project for $50. It's got PA-774/Z565 cloth-lead xformers, six phenolic (sp?) tube sockets and gold input/output terminals mounted, as well as a number of poorly-soldered film resistors and caps and an LCR 200uf filter cap glued beneath the chassis--whoever began the project did a better job at fabricating the chassis than I could have, s/he just didn't have much wiring expertise. It's not tall enough for Baby Blue, I have no idea what plans the original builder was following but rather than start afresh I'd like to strip the existing components and duplicate the Blue board with point-to-point wiring. Since I plan to finish my original blue-board project and would like to eventually experiment with bridging the amps, I'd like the circuits to be identical. I can't seem to find a blue-board schematic, although I could puzzle it out from studying the board--I'm just wondering if anyone has any tips for making the job easier. Also, are there any special considerations if I'm copying the PC board circuit using point-to-point wiring? It kind of offends my sense of neatness since the two amps won't be physically identical but hey, this is all about experimentation, right? I can do some A/B comparisons and circuit changes will be easier with the wired unit. I also just got a free supply of mil-spec 12ga silver/teflon wire, this puppy is begging for completion. Thanks for any assistance/advice anyone has to offer.

[Shannon Parks]

You've got mail!

BTW, I would suggest dumping the adjustable cathode circuits - too much work for point-to-point. I would maybe use a 220 ohm, 3W or better resistor for each pair of EL84s, each by-passed by a 100uF-470uF cap.

Finally, just a note that the new Rev C board uses smaller filter caps and fits in a pretty small chassis.

Shannon

[Geezer]

Thanks Shannon--what are the assembled dimensions of the new board? The tube sockets are already drilled and mounted on my new chassis so I'd be using some spacers and short wiring rather than surface-mounting the sockets--it'd likely still exceed the 2" chassis height.

I guess I could do it right--I've got several pieces of restored tube gear needing cases, and an old friend who owns a custom cabinet business offered me the keys to his shop yesterday for after-hours access. I just need to overcome a phobic fear of large power tools acquired at the expense of two shredded fingertips in high school woodshop. But once I've decided on a Baby Blue chassis template making two won't take much longer than making one. It'll be an aluminum place in a solid wood base. If I can bolster my courage I'll give it a try and forget about the existing 2" chassis, it's too crowded anyhow.

Thanks again.

[tubes4hifi]

Hi Geezer,
you're just about 25 miles or so down the road, I used shorter power supply caps on my old Blue Board (rev A or B) and it fit fine in a 2" chassis.
If you're good at woodworking we need to get together. Email me.
I am currently half done on a new Rev C board, check out some photos on my web page, also anyone interested in custom top plates check it out
www.tubes4hifi.com/st35.htm