V 72 Stuff

Here is a hand drawn V-72 main board, one with dims, one with resistor placement.
Coupling caps are soldered direct to tube sockets.
I will post pics of the actual board maÑana.
Used metric since it's from over there.





Pretty simple, eh?

I gots the pwr supply board up next.

cj

Wow... that sure is simple

Here is your pwr board.
Probably your supply will not end up like this, but just for your original info memory bank.

http://vacuumbrain.com/The_Lab/Telefunken/V-72/v72_pwra.jpg

http://vacuumbrain.com/The_Lab/Telefunken/V-72/v72_pwrb.jpg

Don't thank me, thank Heir Jens!


V72 schematic:

http://vacuumbrain.com/The_Lab/Telefunken/V-72/telev72.gif

and some stuff:

(wow, where the H did I get this!)
http://vacuumbrain.com/The_Lab/Telefunken/V-72/Telefunken1930-31.pdf

http://vacuumbrain.com/The_Lab/Telefunken/V-72/V72SH.pdf
http://vacuumbrain.com/The_Lab/Telefunken/V-72/V75_Schematic.pdf
http://vacuumbrain.com/The_Lab/Telefunken/V-72/V72ASchem.jpg


warning! 5.5 meg
http://vacuumbrain.com/The_Lab/Telefunken/V76/V76.pdf

1/2 a meg:
http://vacuumbrain.com/The_Lab/Telefunken/U273/u273_Limiter.pdf

http://vacuumbrain.com/The_Lab/Telefunken/V376/V376_Schematic.pdf

http://vacuumbrain.com/The_Lab/Telefunken/V675/V675_Schematic.pdf

http://vacuumbrain.com/The_Lab/Telefunken/Sv70/Sv70_schematic.jpg

http://vacuumbrain.com/The_Lab/Telefunken/V776/V776_schematics_compressed.jpg

http://vacuumbrain.com/The_Lab/Telefunken/V74/V74.jpg

http://vacuumbrain.com/The_Lab/Telefunken/V75/V75_Schematic.pdf

http://vacuumbrain.com/The_Lab/Telefunken/W295/w295b_all.jpg

http://vacuumbrain.com/The_Lab/Telefunken/W295/w295_a.jpg

http://vacuumbrain.com/The_Lab/Telefunken/W295/w295b_all.jpg



cj

What modern model of transformers would fit V72 design?

jim

Big thanks, CJ...now if I could just find a couple of tubes I'd be ready to build one.

A P

What modern model of transformers would fit V72 design?

Click to expand...

I think the original output is a 40k:600 isn´t it? Well, it´s not an easy one to find...

Some time ago I´ve contacted HAUFE about making the original V76 parts. I was planning a group buy, but no one in the old Forum showed interests. HAUFE replied saying it would be possible, but they only had lams stock for one hundred chokes and two hundred input transformers. And the price was something like 110 EURo for the choke, and more for the transformer. I do not remenber exact price, but not cheap.

You could contact haufe about making original V72 iron. I bet they will be able to offer something. They do have all the Blue Prints!

Olie at TAB also has all the material and all the blueprints for making an exact replacement. Price shouldn´t be different than HAUFE. More or less the same. And I would say that after all these years that Olie has been researching and building V72 reissues to the original specs, I would rather go with his stuff.

But if you wanna go cheap, I´m quite sure that Sowter has averything you need. Even cheaper would be Hammond, we do not know if the choke they offer is multi-chamber bobbin wound, for lower capacitance, like the original. The original used three chambers, and so does Olie/TAB. Sowter uses two chambers for a 800H choke, and I bet hammond uses just one, but can´t confirm on this.

Also, TAB and Haufe are the only two that has Permendur (Cobalt) for the input transformers. But there are original V72 versions that used a 49% nickel core, did you know it? And it seems that it also works nice. The input transformer that CJ posted here sometime ago is not the only version. there are more "sane" and "easy" versions out there over the time and all the companies that produced V72 amps...

I would say that if you wanna go V72s spend the extra at least on the TAB choke. Other models transformers wold work well, but won´t sound like a telefunken, so for a V72 clone, all TAB iron is the only way. But then again, with so many out there, of different vintage and different components, how does a Telefunken V72 sounds? I never heard one myself, so what the hell am I talking about??? :roll: :?

:grin: Thanks.

:thumb:
Thanks, CJ
:grin:

I owe you a :guinness: or :guinness: :guinness:

wooo-hooo!! BIG, BIG THANKS CJ!! :thumb:
And BIG, BIG THANKS to Jens!!:guinness: :guinness:
-grant

Thanks CJ!

seems worthy of the META.

Hold on, a lot more stuff a c'mon.
I left out a 50 pf cap across the 80K-5K resistors.
Will fix shortly.

Edit: cap now in pic.
update file-it has the same name as the old one.
the trimmer shown on the schemo is mounted on the chassis.

also,
the coupling caps are Not soldered direct to tube sockets, they are on the back side if the board, which I will post a pic of later.

cj

OK, some pics from the lovely units from Jens:

This is the main amp board:
White thing is feeback cap.
Siemens, shown here, used better wire than Telefunken.
Org and Grn coax = input primary wiring.



Front to back: xfmr assy, 2 ea. EF 804S, pwr board...



Pwr board- wires entering tunnel go to cilene dione rectum frier:

http://vacuumbrain.com/The_Lab/Telefunken/Jens/jens_3.jpg

overall- pwr trans has mu can, this is ok with low level stuff.
big pwr trans no good with mu can, saturates the can.
Need heavy metal.
Heavy metal on left is mu shield for in/out/choke assy.
Selinium bridge (no ct on pwr trans) is in that black can.
Circuit board with Freds stuffed in can to retain orig look.
I would not trust those seleniums, they are pretty old and tired.
Reminds me of my days suffering thru Blaupunct car stereo repairs.
Compact, jeeves!

http://vacuumbrain.com/The_Lab/Telefunken/Jens/jens_5.jpg

in/out/choke assy- Telefunken assy on top of Siemens assy.
choke missing cause needs rewind:

http://vacuumbrain.com/The_Lab/Telefunken/Jens/jens_6.jpg

orig 3 chamber chucked up fo some #44:

http://vacuumbrain.com/The_Lab/Telefunken/Jens/jens_7.jpg

input on rt, has newer seperators, clear plastic as opposed to older permali.
sec-pri-sec-sec-pri-sec
that brekout wire melts when you look at it.

http://vacuumbrain.com/The_Lab/Telefunken/Jens/jens_8.jpg

xfmr assy brkt- probably stainless to avoid mag field coupling.
all transformer and choke wiring has to be unsoldered before you can work on any of the iron. Permaliu header plates for terms.

http://vacuumbrain.com/The_Lab/Telefunken/Jens/jens_9.jpg

this is what you will find inside the selenium can.
I was going to leave filter caps for orig sound, but I noticed some swelling and fever among some of the caps so an upgrade willmean more depedability and less hum, possibly better sound.

http://vacuumbrain.com/The_Lab/Telefunken/Jens/jens_a.jpg

[quote author="CJ"]

orig 3 chamber chucked up fo some #44:



[/quote]

Yey, baiby!

What are the lams and how thick is the gap?

lams are snap in werid things, one piece EI, if you can imagine that.
gap is permanent at about 5 thousanths but let me mic it to be sure.

stock dcr is around 12 K.

[quote author="cj"]lams are snap in werid things, one piece EI, if you can imagine that. [/quote]

M42 laminations.

ed

does it make me a nerd if this thread gets me hot?

no, a geek :green:

makes 2 of us who dare to come out... (probably 300 lurking nerds too)

CJ and Jens, THANKS A LOT!!!

:guinness: :guinness: :guinness: :guinness:

[quote author="amorris"]does it make me a nerd if this thread gets me hot?[/quote]

That's what this thread is supposed to be good for :green:

Here is the V-72 choke lam, I measured the gap, looks like 0.020 inches from this side of the periscope.

http://vacuumbrain.com/The_Lab/Telefunken/Jens/v72_choke_lam.jpg

See that they must toss out, or recycle, the metal in between the legs when stamped.
You wouldn't want to do this to a Ni lam, unless you wanted to go bankrupt.
Your typical "scrapless" EI lam means that no steel is wasted, the shape of the lam adds up to a square or rectangule, depending on the leg length.
The steel stamped out in between the legs is, well, grounds for a divergent joke that I just thought of, but we know better, anyway, scrapless means no waste.

One advantage of this choke lam is that the gap don't drift!
And it is probably tempeture compesated!
The choke gets hot, the tongue expands, (yeah, baby!) , but the legs expand with the tongue.

:grin:


So, you are saying, how the heck do you lace up the darn choke coil!
You carefully bend the lam.
Here is how you snap it in, good to know if you are trying to "snap it out" without destroying the lams, or the coil:

http://vacuumbrain.com/The_Lab/Telefunken/Jens/v72_lam_install.jpg All lams face the same way, face down on Broadway, so that when all are in place, the bobbin can be "tweaked" down a bit, which covers up the gap and kind of cleverly holds the whole enchillada together.

This is a non square stack, 1/2 by 5/8, 0.0145".
Needs to be taught, do to the bending, would not want to use a thinner gauge. This lam is half a ten thousandth over the standard 29 ga.
Don't want to say M6, probably had their own recipe as far as steel alloy and anealing.