Tom Mobley Posted November 30, 2003 Share Posted November 30, 2003 I have a 222C power transformer being repaired, the guy asked my how voltage is required to be present at the leads. These are the red and red/yellow leads that go to pins 4 and 6 of the 5AR4 rectifier tube. These are the leads that provide the high voltage that ends up being B+. The file attached shows it to be 430V off the rectifier, but how much is it going into the rectifier? There's losses in rectification, right? The attached .gif of the schematic shows this 430 off the rectifier but doesn't say what's going into the rectifier from the transformer. Id there a standard formula for figuring this or is unique to each rectifier tube/amp design? I remember reading something on this awhile back but sure can't find it now.... Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 30, 2003 Share Posted November 30, 2003 I'm going to guess at 360V 360V Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted November 30, 2003 Author Share Posted November 30, 2003 at http://www.bonavolta.ch/hobby/en/audio/supply.htm the guy posts this chart: "# The output voltage of a tube diode is about 90% of its input voltage, here are the insertion losses of some common tubes compared to solid state technology: 83: 2-3% 5AR4/GZ34: 3-7% <----- our case here 5V4/GZ32: 6-12% 5U4/GZ37: 8-16% 5R4: 12-22% 5Y3: 13-23% 6087: 18-30%" using worst case, 430 x 1.07 = 460.1, pretty good guessing there Craig. anybody got any brilliant alternatives? otherwiser, I'll call him tomorrow give him that number. Tom Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted November 30, 2003 Author Share Posted November 30, 2003 oooops, 100 volts off. did you mean 360-360 really? not 460-460? how does 360-0-360 become 430? lets see 360 up and down is a 720 peak to trough: 720 x ( 2/Pi) = 461 hmpf, that's what I had before. Where's Deneen when we need him? Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted November 30, 2003 Share Posted November 30, 2003 Tom, My first guess was 350V then I went down and fired up a 299A and adjusted the Variac to 117 volt which produced 360V . I'm about 99% sure this will do it for you. The worst case scenario would be you have to adjust the value of the first dropping resistor so no big deal. I bet 360V does a fine job though. I've measured many before and they are usually real close to this in the Scott 7189 amps they just used a different dropping resistor for the different amps. Remember that the voltage will be higher and how much will depend on your wall voltage when you put it back together. Craig Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted December 1, 2003 Author Share Posted December 1, 2003 Thanks for taking time to check into it, Craig, I appreciate it. Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted December 1, 2003 Share Posted December 1, 2003 Hey no problem is Phil from are favorite tranformer company repairing it for you ? Craig Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted December 1, 2003 Author Share Posted December 1, 2003 Craig, Yes, I sent it to the usual suspect, but Phil doesn't ring a bell. I'll check on that. Ryan Thanks for posting that, I knew there was a sq. rt of two in there somewhere, I even had the 509 at one point, but couldn't remember the whole thing. Tom Quote Link to comment Share on other sites More sharing options...
NOSValves Posted December 1, 2003 Share Posted December 1, 2003 Mark, The usual excellant and easily understood posting ! Man I wish I had your talent ! Tom, What is your contacts name ? Craig Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted December 1, 2003 Author Share Posted December 1, 2003 Mark, There's dumb luck and then there's educated and experienced dumb luck. Not much doubt here as to which one you're taking advantage of. Thanks to all three of you guys for posting here. Is this a great forum or what? I've already copied all these into a doc, I'm sure I'll need them later when I build an amp (or two). Tom Quote Link to comment Share on other sites More sharing options...
Tom Mobley Posted December 1, 2003 Author Share Posted December 1, 2003 Craig, I talk to a guy named Aldan there. I think that's the right spelling. Tom Quote Link to comment Share on other sites More sharing options...
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