OT: Need help with a tube transformer.

[sir_modulus]

Hey all, I just found a RCA Victrola record player. I thought it was junk, but found it had a tube amp inside(I took the good tubes (Sovtek 2 EL84's and a 12AX7)) now my question to you is about the trannie in there. There is this massive power transformer, and i decided to test it. One side has a big metal plate over it and the other side is open(inside the amp chassis). On the open side there are 9 Wires. I put 120Vac on the two leads(on side A) that were previously hooked up to power. The other two leads on side A read 40V. There are five leaads on the other side. One 30V AC output and one Centertapped 600V output (so i can also get 300V) This trannie has the markings 3963-3 and DYE 1 and has some wax like stuff on it. I know a lot of amp schematics use either 180-200V or 275V to power them. I want to know if anyone knows any 300V (or 600V) B+ tube amps?

P.S. I found some other weird things. I'll post pics later, but two small trannies that i think are output transformers(there are also two speakers so that might be why there are two) and i found two small transformers with only 2 leads each. Are theses transformers modded to be inductors?

[petemoore]

About ten years ago I got an RCA Victor console, I removed the amp [two frames], and speakers and re-mounted them in a more compact homemade wood boxes, and replaced the EL84's.
 I use this amp all the time, at a 40$ investment level, I find this amp is great sounding [gonna be hard to beat for 40...] and sounds very close to [when A/B tested] against a Fender Deluxe...-reverb. At least 'comparable' in output and sound quality.
 I don't know how to read and write as well as you do about Tube Transformers...but you have a very nice sounding amp there if it works right

[Paul Marossy]

There are a lot of tube circuits that use a B+ of around 300V. It depends on the current capability of transformer is. That will govern what you can do with it.

[Lonestarjohnny]

Sir Modulus, You have what sounds to be a 50 watt Stereo power amp, If it has 2 output trans., Best to post a picture showing the top of the chassie, and a shot of all the transformer's, the 2 small transformers with only 2 leads are choke's, now is the Primary voltage 120 ? also normally the info for voltage input and Sec. output will be stamped on the paper side of the Transfomer, some time's you have to look very close if it's got a lot of wax buildup on the paper, with EL 34 power tube's she could be running as high as 600 v. on the Secondary's, because back in those days the Mullard's were rated at 800 VDC, nuff voltage to make the hair Curl on your neck, LOL! so be careful and yes that old amp could make you a Great Sounding guitar amp.
I'll wait for you to post some Pic's
JD

[Lonestarjohnny]

Sorry, I missread your post, My Bad ! :oops:
2 EL84's are gonna give you about 18 to 25 watts, still a good find, you can still build a nice amp out of it.
JD

[Paul Marossy]

18 to 25 watts can still give you a very loud amp. I am interested to see what you come up with.  

[ErikMiller]

That's a great power transformer for a guitar amp. The Fender Champ used a 300-0-300 PT.

Older output transformers usually have 3 leads (unless they have multiple output impedances available). The 2 inductors you have that have only 2 leads are probably chokes.

The best way to figure out what all these parts are is to see where they are hooked up before you disassemble the amp. If the 2-lead guys are in the power line, they're chokes.

If you want to build a tube amp, I recommend you visit www.ax84.com and look through their forum. Lotta great information and people willing to help. It's the tube amp version of DIY Stompboxes.

[Aharon]

You can build any of the great amps that use 2XEL84 tubes like the Vox AC15 and the MAtchless Spitfire to name only two.
Aharon

[petemoore]

My RCA Victor has 4 X EL84, two for each side of stereo output.

[petemoore]

I was reading the old but great RCA Tube manual, and decided to
Email pmmillet in regards to old RCA amplifier schematics...we'll see what happens.