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Old 22nd February 2013, 10:00 AM   #1421
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Zoe,
Please post pic of build, if you dont mind. Inquiring minds want to know.
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Old 22nd February 2013, 11:26 AM   #1422
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Quote:
Originally Posted by Zen Mod View Post
put fat and short(est you can manage) wire between two central grounds of two main pcbs

that will look as bridge between them
Humming problem solved.

I think there are some conditionalities in the schematic of dear NP. He forgive me if I'm saying something stupid, but after several tests is my interpretation

One is the choice of transformer, I have a 2x24VAC, has no center tap, so I only have 24V on each winding, they are completely independent, can unite in series but I'm not 48V.

And it was here that I received what seemed like half-wave rectified.

I used the layout of the original full F5TV2 only takes a bridge when I joined two exits to the GND got a common point, and the other two will bridge that connected, but in this case 0 Volts enters and exits the bridge 0 Volts.

Only when I connect GND will get that PSU is 24V to 24V and over one side to the other side, but there is failure in the rectification of the union that always behind AC.

disassembled the entire PSU, soldered everything again, and used a bridge to each side, all was well, I notice less 2V on each rail, with only one bridge there is less voltage drop and would be faster.

in short, one can not use only transfores with independent side with a bridge rectifier has to be toroidal with center tap.

I'm using two KBPC35404W, but I need faster, someone gives you a hint ...
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Last edited by Blink_PT; 22nd February 2013 at 11:32 AM.
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Old 22nd February 2013, 12:26 PM   #1423
henryve is offline henryve  South Africa
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Blink

I really struggled to understood what you are trying to say, but I think I get some of what you are saying and that tells me that you have an inbalance between your 2 transformer secondaries, which is exactly why NP uses 2 bridges when having 2 separate secondaries.

I think you had DC going back into your transformer which caused it to hum. Am I making sense here?
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Old 22nd February 2013, 01:05 PM   #1424
6L6 is online now 6L6  United States
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I think he had the transformer secondaries windings wired incorrectly to make a 'center tap'
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Old 22nd February 2013, 01:08 PM   #1425
omishra is offline omishra  India
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Blink, just exchange one of the blue or red coloured wire from your diagram with its another counterpart of same color. It seems you haven't done series of secondaries correctly.
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Old 22nd February 2013, 01:15 PM   #1426
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Quote:
Originally Posted by henryve View Post
Blink

I really struggled to understood what you are trying to say, but I think I get some of what you are saying and that tells me that you have an inbalance between your 2 transformer secondaries, which is exactly why NP uses 2 bridges when having 2 separate secondaries.

I think you had DC going back into your transformer which caused it to hum. Am I making sense here?
No, not that. My secundarys has 24V each, are equal.
The problem that can not just use a bridge rectifier with this type of toroidal 0-24, 0-24. They are two independent windings.

I wonder if any member has connected two independent secondary with one bridge.
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Old 22nd February 2013, 01:28 PM   #1427
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Quote:
Originally Posted by omishra View Post
Blink, just exchange one of the blue or red coloured wire from your diagram with its another counterpart of same color. It seems you haven't done series of secondaries correctly.

This is not toroidal 24-0-24.

It is 0-24 + 0-24.

Red + Red = 24V
Blue + Blue = 24V

Join any red any blue, never gives 48V, measured in total 0Volts.

Maybe if I had already ordered with center tap work because the winding would be the same, with a connection to medium.

What matters is that now is working very well.

He liked to have the bridges faster, any suggestions?
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Old 22nd February 2013, 01:40 PM   #1428
Zen Mod is offline Zen Mod  Serbia
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see ;

you have good xformer ; just need little more to think about
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Old 22nd February 2013, 01:42 PM   #1429
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that is no problem, as long as one conect the secondaries correct.
there is no difference between a centertap transformer and a dual sec transformer with the secondaries in series (conected correct)
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Old 22nd February 2013, 04:43 PM   #1430
zoe is offline zoe  United States
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Here are some pix of my amp.I was up late last night reworking amp changed resistors in cascaded front end to get 13.3 volts to little fets as they had only 10v before.Also sodered bigger wire for ground bridge and increased resistance to RCA ground wire. I've got the two Anvil Lindberg 625va 25v tranys (parts express) hooked together.I wanted to try one and then two to see the difference. Two is better. Amp still has buzz louder now. Left channel is dead quiet.also changed preamp no difference.
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File Type: jpg 2-22-2013 amp 011.JPG (546.5 KB, 288 views)
File Type: jpg 2-22-2013 amp 009.JPG (560.7 KB, 264 views)
File Type: jpg 2-22-2013 amp 008.JPG (585.1 KB, 174 views)
File Type: jpg 2-22-2013 amp 001.JPG (559.6 KB, 203 views)
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