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When changing an amp from a tube rectifier to solid state using diodes and a small board........what is the best way to deal with the unused 5 volt heater winding? Leave the 2 wires open? That should keep them inactive and out of trouble, right?

Amp in question is an AA764 Champ build with a 6L6 conversion. I can use the extra voltage that will be created/free'd up. :)
 

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Try one of these & don't worry about any of the wires at all?: Solid State Rectifier | TubeDepot.com
This is something I might consider in the future. At least try to see what improvement it might have. The only thing that worries me is the note that is listed on the site.

Please be advised that this replacement will increase overall B+ (plate voltage) by 10-20%. If your filter caps are older than 20-25 years, we suggest you replace them before installing this solid state rectifier.
If it is harder on older caps I wonder if it decreases the normal life of newer caps.
 

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Any solid state rectifier will raise the voltage. There is significant voltage drop when using a tube rectifier, but not when going solid state. As long as your caps are rated properly for the voltage you'll be fine.
There are a number of reasons for the warning, but if your caps are new and rated high enough, no problem.
 

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Discussion Starter · #9 ·
Any solid state rectifier will raise the voltage. There is significant voltage drop when using a tube rectifier, but not when going solid state. As long as your caps are rated properly for the voltage you'll be fine.
There are a number of reasons for the warning, but if your caps are new and rated high enough, no problem.
I was reading that a 5Y3 has an internal resistance equal to about 240 ohms. That's a fair amount of voltage drop. The other popular rectifiers aren't as bad, only about 120 ohms. Either way, it's going to make a big difference, specially when your wall socket is reading 123 or 124. I was planning to use a 40/20/20 @ 475V filter cap. Should be enough for one of those little champ/Princeton PT's.
 

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When changing an amp from a tube rectifier to solid state using diodes and a small board........what is the best way to deal with the unused 5 volt heater winding? Leave the 2 wires open? That should keep them inactive and out of trouble, right?

Amp in question is an AA764 Champ build with a 6L6 conversion. I can use the extra voltage that will be created/free'd up. :)
Leave it open yes, BUT the best way to do this mod is to use the unused pins on the rectifier socket to wire up the diodes (no need for a board) with a switch to go back and forth (tube vs ss rect.). Alternatively, buy an octal tube base (e.g. : 8 Pin Octal Tube Base Only | TubeDepot.com but your favorite tube/amp parts supplier should have them as well) and wire the diodes into that (they sell premade ones but stupid expensive for what they are) and just swap it for the tube (better if you don't want to drill the panel for a switch).

If you have The Garnet Book there's a bit where he discusses the switch on the socket method (schem as well as diagram of the tube socket showing how to wire it up - easy peasy) which is where I got the idea from (most of my amps are SS rect already, except one, but I use that for dirt so no need for SS - I will be implementing the switch in my Champ/Herzog with Stinger build, which I have not touched in 6 months due to busy).

[edited for clarity]
 

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I like to snip them so there is no wire protruding past the insualtion, add a bit of heatshrink over the ends, then bunch them up and zip tie.

Same advice here
Keep the wire long if possible- you may want to install a rec tube one day. Snip , insulate, coil, tie, tuck away :)
 

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Discussion Starter · #12 ·
Same advice here
Keep the wire long if possible- you may want to install a rec tube one day. Snip , insulate, coil, tie, tuck away :)
Good advice. I may want to use that transformer in another build someday, of return that amp to a 5Y3
 

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One slight word of caution. Replacing the tube rectifier with a solid state one can actually increase heat dissipated in the transformer. Since it a little one, it's good to keep that in mind as the surface area is not that large and consequently cannot dissipate heat as efficiently as a larger one. As long as you have a quality power tranny, you should be ok.
 

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Discussion Starter · #14 ·
One slight word of caution. Replacing the tube rectifier with a solid state one can actually increase heat dissipated in the transformer. Since it a little one, it's good to keep that in mind as the surface area is not that large and consequently cannot dissipate heat as efficiently as a larger one. As long as you have a quality power tranny, you should be ok.
Good advice, thank you. I'm using the upgrade Hammond 291AEX. I like them because they have a center tap on the 6.3V heater windings.
I was going to use a 40/20/20 @ 525V filter can, but I have since thought maybe a good quality 20/20/20 might be easier on the PT. Never thought about the heat aspect at all though.
 

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While you are increasing heat dissipation due to the SS rectifiers, it will not be a drastic increase. It is also helped along by not using the 5V filament winding. This allows the other windings to dissipate a bit more heat.
On the contrary, with small power transfomers, there's always the risk of heating issues. The difference in heat saving from leaving the 5V open can be offset by the heating created by the loading on the transformer due to the negligible resistance of the B+ capacitor and diodes. If this was a larger amp with more robust transformer, it wouldn't be a problem.
Since you've stated that you've upgraded the transformer, it shouldn't be a problem.
 

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Discussion Starter · #17 ·
I imagine those little "champ" power transformers are really running on the edge when they are powering a Princeton Reverb with 4 - 12A's and 2 - 6v6's. SS rectification must almost put one of them into meltdown mode. :)
 

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Discussion Starter · #18 · (Edited)
Well, I hadn't been working on this amp much lately but I finally got some time and finished it to the point of being fired up today.

I tried to go with carbon comps in the signal path, and what I think are
Cable management Electrical wiring Computer hardware Electrical supply Wire

good caps every where. I've heard so many difference opinions on caps, I'm not sure anymore what's truly good and what's just a waste of money.
6L6 power tube with an upgrade 15 Watt output transformer, Classic Tone #40-18031. Power transformer is a Hammond 291AEX. Chassis is from "zachmhunter" on eBay, boards & carbon comps are from "chuck0562" on eBay. Chassis front panel and back sticker are from MojoTone. Misc parts from everywhere else on the planet it seems.

First fire up with the tubes in it, I was greeted by one of those ear destroying, eyeball exploding, squeals I've come to know & love. With only one power tube I wasn't sure what to do.......but I reversed the leads to the OT and the problem was solved. Amp is nice and quiet too. I must be learning as I go. A big thanks to all the techs here who have supported me and put up with me on my (learning) journey. You guys are the best, and I couldn't have done any of it without you.

Cabinet will be a slightly tall BF Champ style with a pair of 8" speakers.
 
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