Neater Wiring - Cable Lacing

[loudthud]

I like many of the old Sunns, but the ones I've worked on have a problem with quiescent noise (sceptre and solaris come to mind). I suspect that much of this is due to ground loops. I would like to really take some time and track down the source and come up with a ready, serviceable fix for these.

I feel your pain. Grounding on old Sunns is a nightmare. About the only thing done right is the cathode of the first triode is returned straight to the input jack ground (on some models). The laced wiring harness makes tracing things out very difficult. You won't find any kind of layout anywhere.

Issues:
1) Can filter cap with 4 sections and common ground to chassis. (Later examples have axial cap as first reservoir cap.)
2) Center tap from transformer soldered to chassis near transformer.
3) Aluminum Pop rivets hold terminal strips to chassis for some grounds.
4) Cross talk in wiring harness (?)

I've tried soldering the terminal strips to the chassis with varying results. I built a couple of eyelet boards to hold series connected snap-in caps to replace the old style can filter caps. Bass and PA amps have space to put the board where the tremolo-reverb board would be positioned in a guitar amp. Sometimes I wonder if I shouldn't rip out the wiring harness and start over.

[Justin Thomas]

I have often wondered how hard it would be to put two ground tabs on a cap can - one for the power tube plates & screens & one for the other sections (or however the convention goes fir the improved ground schemes). I guess the CE cans are fairly set for a layout & are designed to direct-fit old Mallorys, but JJ & F&T might be able to work it in. I'd almost give up a fourth cap section if it meant two ground tabs...

Justin

[soundmasterg]

I have often wondered how hard it would be to put two ground tabs on a cap can - one for the power tube plates & screens & one for the other sections (or however the convention goes fir the improved ground schemes). I guess the CE cans are fairly set for a layout & are designed to direct-fit old Mallorys, but JJ & F&T might be able to work it in. I'd almost give up a fourth cap section if it meant two ground tabs...

Justin

Weber used to make custom can caps where you could specify separate grounds. I did that for a couple but didn't used them yet. The problem with those can caps was they had a wafer base that was super glued to the metal base of the can, and it was so thin there just wasn't enough surface area to ground to and the base would eventually come unglued, which isn't a cool thing to have happen. I reglued the couple I used that came undone but it was a poor design for the base and I didn't get any more.

Greg