Gyuri's Pass SONY VFET2 build.

[Zen Mod]

I would hardly accept even half of that

bloody 23W of heat

bad tranny

 

[Gyuri]

I was afraid from it.
The man from whom I bought, he says, there are two other pieces:
These are sucks about 120mA.
Anyway he did not say how much was the primary voltage.
Suspected it is 230V.
I haven't checked yet, is there a short circuit caused by outer shield.

 

[Gyuri]

bad tranny

I certainly enjoy it, if I could allow to myself a purchase like this:
600 VA - Shop Toroidy.pl
But I can't.
Customs duty and other taxes was about 90$ for the kit.
And I'm in trouble with chassis.
The heat sink, which I have so far I used for my previous builds, it can not be purchased anymore.

 

[Zen Mod]

I know for boyz in your neihborhood

hmtrafo

then add .hu

they're good , supposedly

I don't wanna post their proper web site addy , just because they're ignoring my emails ...... but you can call them or visit them - my friend took amorpous cores from them , for bigbada$$ zeroformers

 

[Gyuri]

Thanks.
I have more or less familiar with the domestic supply.
Not much cheaper than in Poland.

I'm wondering, what if I would connecting in series two of that TH173?

 

[Zen Mod]

primaries in series , no good

drek, even with rock solid steady load

 

[Gyuri]

Many thanks for your help!
Then I reject this idea which was stillborn.

 

[Gyuri]

primaries in series , no good

drek, even with rock solid steady load

Well, this is obvious, if I'm thinking of it a little.

 

[Gyuri]

It's now really just a thought experiment:
What if I connect primaries of two equal transformers in series while secondaries in parallel?

 

[Gyuri]

I have even more crazy ideas:
There are two 220VAC/110VAC (230VAC/115VAC) trannies from above-mentioned BULL computer.
These are at least 1500-2000VA ratings I think.
So I use one of them to supply that TH173.
It sucks some 5-6 mA at 115VAC.

 

[Zen Mod]

you'll still have drek in chain , whatever way you choose to feed them

bad tranny is bad , how long you can expect of them , to go even worse ?

 

[Gyuri]

I can understand you.
I decided that this tranny must have to go.
I will try to choose from two other.
Or, do you think, I must forget those ones?
I would rather ask the money back?
It was about 50$.

 

[Zen Mod]

you can either ask money back , or give it to them as gift

but tranny is drek , no need to bang your head why and how

btw. what is that right one donut on picture ?

 

[Gyuri]

I think there is some short circuit in outer magnetic shield.
Maybe it has some other problem, I don't know.
I will try it to exchange for a better one.
It was too pricey for me to give it to a (poisoned) gift.

Right one is courtesy of our forum member Sajti.
I bought two from him.
One of them heating my 4xF4.
These one measures 33mA at 274VAC.
It is designed on 1500VA core for 1000VA power.
It has 2x25VAC secondaries, and 2x160VAC and 6.3VAC for possible tube stages.

 

[Zen Mod]

I think there is some short circuit in outer magnetic shield......

outer magnetic shield - you mean case or blind winding (static shield) ?

 

[Gyuri]

That metal housing forms a winding.
Not really short circuit, that aluminium hole of that big central screw not isolated galvanically from housing.
I suspect there was originally an insulation, but they tighten that screw so much, that it is now passed away.
I expressed it so beautifully.

 

[Gyuri]

Doesn't matter.
That tranny must have to go, it is for sure.
It would be good to know, how much current sucks a tranny like this, if it is in perfect condition.

 

[Gyuri]

That one has gone.
I have two other ones.
These are good for my opinion.
I'd like it to power up tomorrow.

 

[Gyuri]

I have some questions.
Papa said, R15/R16 values
with 24VDC supply:
22V=2.5V*(R15+4750R)/4750R
22V*4750R/2.5V=R15+4750R
41800=R15+4750
37050=R15

with 28VDC supply:
26V=2.5V*(R15+4750R)/4750R
26V*4750R/2.5V=R15+4750R
49400=R15+4750
44650R=R15 -> actual value on schematic is 41200R

with 30VDC supply:
28V=2.5V*(R15+4750R)/4750R
28V*4750R/2.5V=R15+4750R
53200R=R15+4750
48450R=R15

Is it correct or I missed something?

For me, with that tranny I have, I get 29,5VDC loaded by my F6 at 1.3A/rail/side.
So with this, estimated rail voltages will be around 30VDC for my Sony VFET amp as well.

Which R15/R16 values I can choose?

Kind regards,
Gyuri

 

[Gyuri]

Or it doesn't matter, because Papa also said:

"This amplifier is designed to operate with voltages between about +/-26V DC
and +/-30V DC."

So I can drop in something I have, for example 42.2Kohms or 47.5Kohms.