453 VDC from a 5Y3

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C Moore
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453 VDC from a 5Y3

Post by C Moore »

Is it "normal" to see 453 volts on pin 2 and 8 of a 5Y3 rectifier?
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M Fowler
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Re: 453 VDC from a 5Y3

Post by M Fowler »

Depends on your secondary voltage. Typical champ/deluxe circuit has 325v to 360v on pin 2 and 8 of the 5Y3 using a 300v secondary.

Mark
Last edited by M Fowler on Wed Mar 25, 2009 12:21 am, edited 1 time in total.
C Moore
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Re: 453 VDC from a 5Y3

Post by C Moore »

http://f1.grp.yahoofs.com/v1/IErESQfqvK ... ematic.pdf

Should have included this already, although it is does not follow the original amp 100%. This is the schem I used when I replaced all of the components and one of the tube sockets. Originally there was a giant 1K coil type resistor where the first 4.5K is on this schem. The 4.5K drops the voltage too much though. At that position I have a 5 watt 1K cement. It gets hotter than hell. Guess I will have to list some of the other volt readings, but they seemed kind of normal IIRC.
Can't figure out why the voltage right from the 5Y3 is so high. I will have to post some plate voltages tomorrow.
Thank You
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M Fowler
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Re: 453 VDC from a 5Y3

Post by M Fowler »

hired hand,

That link did not work for me?

Mark
C Moore
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Re: 453 VDC from a 5Y3

Post by C Moore »

M Fowler -
Not sure how to help with the shem link. I can open it without being logged in, as just a casual observer. I appreciate your effort. Maybe I should try to send it to you in a PM or email.
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M Fowler
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Re: 453 VDC from a 5Y3

Post by M Fowler »

I got your PM but that link doesn't work. If you have this schematic on your computer then attach it to your thread.

Mark
C Moore
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Re: 453 VDC from a 5Y3

Post by C Moore »

Oh Man, sorry about all this, computers are not my forte. I have attached it to my OP.
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M Fowler
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Re: 453 VDC from a 5Y3

Post by M Fowler »

Thanks for the schematic

318v is shown so the transformer is 282-0-282 into 5Y3 rectifier tube equal 318.66v. There is a conversion factor of 1.13 for the 5Y3; 1.3 for GZ34; and 1.2 for 5U4B.

250vAC into 5Y3 = 282.50
275vAC into 5Y3 = 310.75
280vAC into 5Y3 = 316.4
282vAC into 5Y3 = 318.66
300vAC into 5Y3 = 339
325vAC into 5y3 = 367.25

Go with the 275-0-275 or 280-0-280 tranny. Most common in champ is 250-0-250

Mark
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M Fowler
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Re: 453 VDC from a 5Y3

Post by M Fowler »

Check your secondary voltage.

453v divided by 1.13 factor = 400vAC secondaries and you want to get down to the 318v I assume, right? 453v-318v = 135v difference. So zener diode NTE5289AK would reduce by 130v wired to the center tap of the tranny and bolted to the chassis for heat sink.

Hope this helps and maybe others will give us a shout too.

Mark
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Structo
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Re: 453 VDC from a 5Y3

Post by Structo »

That's what I did with my Hammond amp.

130v 50watt zener from center tap to ground.

Be sure to buy one that is cathode to base.

I dropped from 460 to 322v.

Be sure to use heat sink compound between chassis and zener.

I also bypassed the zener with a .01uf ceramic to help quell the switching noise.

Worked great!
Tom

Don't let that smoke out!
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Structo
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Re: 453 VDC from a 5Y3

Post by Structo »

Hey Mark,

Where did you find the multipliers for the voltage after the rectifier tubes?
Tom

Don't let that smoke out!
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M Fowler
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Re: 453 VDC from a 5Y3

Post by M Fowler »

"Inside tube amps" by Dan Torres.

The book is filled with good information and has been recommended reading by many other tube amp book authors as well.

I had Dan personally rebuild my Super Reverb and it sounds like crap, so some day I will be rebuilding that myself. Of course a transformer upgrade could probably help this amp out.

Mark
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