V 72 Stuff

[guavatone]

[quote author="martthie_08"]
One thing boggling my mind: The factory installed caps have metal pins which go through the plastic mounting board and are then turned to physically hold the caps in place. (see pic below) Question: are these also the electrical connectors for the caps? I am asking because there are no wires on the "-" side and there is no continuity to 0V.

[/quote]

On my V78 there are neg. connections to ground on the opposite side of the caps. Like regular axials. The thing is that both those tabs on top are connected to positive. I recapped with Sprague Attoms and with some hot glue on top and connecting all the bottom grounds you should be golden. I still have to old caps-lord knows why......

 

[CJ]

yes, they spot weld a tab on the ground side of the cap, to the actual case.
you can get those tabs welded on at a battery place, at least if there is a big ni-cad dealer,
we have Batteries Plus out here, they made a zillion on computer back up
also have all the ni cads from that james bond movie, was that thunderball with al the all giddings underwater action, sleds and stuff?
well, they used the batts for the pic, and that was it.
the ni cads powered the dc motors in the sleds.

there is limited space for recapping the v72.
thery kind of sandwiched those suckers in there between the floor board, and the fire wall.
they sell the right size, use the same uF for the same sound, maybe go a little higher on C1.

 

[CJ]

err.they spot weld the tab on the Positive side, sorry!
I hope yo aren't dead yet.

noteic links fixed

cj

 

[martthie_08]

CJ, thanks for putting your stuff back on, very nice :thumb:

I haven't done any more work yet though, managed to sneak in a short vacation.

Did you end up replacing the rectifier?

 

[CJ]

yes, FREDs's put on a pc board that i burned.
the board fits inside the can so it still looks original.

 

[Greg]

I have a pair of these. Not mine, of course. The owner said one channel is acting funny. They've been sitting in my shop for a month or two. I'll get working on them eventually.

 

[CJ]

you have a lot of work if its been worked.
pwr trans,choke, output need to be re wound.

why?
1)orig were sloopy, wire crossovers, reliabillity issues, short turns, depending on which factory made it
2)see #1

otherwise its wait til it pops, which will be in the middle of Frank's .....hmmm....Frank is dead, right?
Did they ever find his kidnapped son?

rewind with Nomex insl and these pups burn forever.

 

[martthie_08]

getting to work on the V72 recap, just a quick one: Are caps 31, 32 and 33 on the schematic electrolytics? If so, are they bipolar? This is what I'm talking about (click for larger pic):



What would be a good substitute for these? I guess I could fit some Solen's or something film in there, would that be a good idea?

 

[CJ]

you drive a VW?
just go out and dig around the distributor for that bosch feed back cap.

i dont think you need to mess with the silver cans, just those 5 guys in the pwr supply, with the cardboard covers or not.
those are polarized lytics.
stick with the same values, brand should not matter that much with this circuit.
size will be the big hassle.

 

[CJ]

Paging Mr Ed...
sorry about the gamma correction, or lack of.

http://vacuumbrain.com/The_Lab/V72/72out_b.jpg
http://vacuumbrain.com/The_Lab/V72/72out_c.jpg
http://vacuumbrain.com/The_Lab/V72/72out_d.jpg
http://vacuumbrain.com/The_Lab/V72/72out_e.jpg
http://vacuumbrain.com/The_Lab/V72/72out_f.jpg
http://vacuumbrain.com/The_Lab/V72/72out_g.jpg
http://vacuumbrain.com/The_Lab/V72/72out_h.jpg
http://vacuumbrain.com/The_Lab/V72/72out_i.jpg
http://vacuumbrain.com/The_Lab/V72/72out_j.jpg

 

[edanderson]

thanks cj.

 

[guavatone]

[quote author="martthie_08"]ok, I can't get the HI-Z input working properly, I'll come back to this when I understand a bit more about tube circuits.
[/quote]

did u get this working?

 

[martthie_08]

nah, this particular unit I was working on was really buggy to start with and I didn't have the patience to look into the DI thing. It turned out it was the damn fuse holder, replaced it and it's working fine. It was all green and some smartass put a 4A fuse in there :roll: Thanks CJ :guinness:

 

[CJ]

I blew my fuse trying to beat this guy:

http://www.guitarshredshow.com/

hey, check out "five oclock shadow man" on the strat:
dude spent ten years and 5 tons of coffee on someone elses chops!
no one told him when to run
he missed the starting gun
ex crack head, looks to me...

http://www.mastertheguitar.co.uk/mtr/17/

that does it, im building a strat:

http://www.desopolis.com/midwest/Strat1.htm

 

[Freddy G]

Hey CJ,
You might wanna try a Lester while you're at it :wink:
http://home.cogeco.ca/~fritz/lespauls.htm

Freddy

 

[CJ]

these guys are good, it would take me years to get all the tools and learn that crap.

i would like to see him build a Mary Ford.

 

[Freddy G]

these guys are good

Thanks!

I'd love to build a Mary Ford.....I'd just need to get my hands on the original to backwards engineer her! :green:

 

[hagen daaz]

[quote author="rafafredd"]

What modern model of transformers would fit V72 design?

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

[/quote]

Reading "Recording the Beatles" book, they said the REDD desk use a 200 ohm output because the 200 ohm standard inside EMI.

 

[jensenmann]

German broadcast standard was 300 Ohm if we´re talking about the "usual" V72. Don´t know about the EMI stuff though

 

[Gabriel Sousa]

i would love to build a v72....

are you , working on that ?