Rewinding UTC interstage transformer from BA6A

[22busy]

I'd really like to be able to repair a UTC interstage transformer from an RCA BA6A that has a bad primary winding (I think it's open but it's been awhile since I messed with it). I was just reading C.J.'s very informative post about the UTC HA100 transformer and how a new one could be made up from a less popular unit's core, and it made me wonder whether it would be possible to have my blown UTC interstage transformer rewound to original specs.

It would be wonderful to be able to get this piece up and running again. Is this a job that could be done DIY? Or, can anyone suggest someone who would be willing to tackle it and who would do a good job?

BB

 

[CJ]

Was the UTC stock in the BA6a?
We have been dying to get the specs on that x-former!
If you want, I can reverse it, then rewind it for you!
That way I could give the specs to Brian Sowter, who has been asking us for help.
Give it some thought before you say yes or no.
cj :guinness:
Darn it! When I read that about the Ba6a, I almost fell out of my chair!
I lost track of the turns on the 100X!
Now I have to wind it up and start over!
:grin:

btw, is there any kind of part number on that x-former?
And good luck to Ollie who is going in for heart surgery!
:shock:

 

[22busy]

Wow, I must be living right. This place is wonderful!!!!!!!!!!!!! Thanks C.J.

I've actually got 2 of these transformers that developed the same problem, and yes, they are the original UTCs that came stock with that unit. You'd be welcome to reverse engineer one or both and I'd be very happy to pay to get either or both back up and functional again.

The transformer is contained in a pretty large circular can, about the size of a coffee mug. Printed on the outside of the can it states: "Made for RCA by UTC" and underneath is the number "F-7770". In small letters near the bottom of the can is "CW30". There is one other number on the bottom near the lugs. It reads "949097-1"

The transformer has what appears to be a center tapped primary (for balanced operation) and a single secondary. I just checked and one side of the primary is open. I think it must have been from too much DC. If I can get some batteries for my digital camera I'll post a pic or two.

Really sorry about your HA100 snafu C.J. I hope the interstage tx can be of some help to you.

If you want to PM me I'll send you my email address and contact info.

Bruce

 

[CJ]

I was just kidding on the 100x!

Well folks! It looks like we finally found the BA6a inerstage!
I will do it for free.
Payment will be obtaining the knowledge and the fun of unravelling yet another classic!
I really do love doing this!
:guinness:

 

[22busy]

Got your PM C.J. My hat's off to you.

If anybody is interested in detailed photos of the BA6A layout I'll be glad to provide them.

It is a monster sounding compressor (and there's a tremendous improvement in sound when it's working :shock: ).

Bruce

 

[CJ]

Heck yes on the pics!
Does this place rock, or what!!!
:guinness: :guinness: :guinness: :guinness:
Happy Friday everybody!

 

[adrianh]

Off topic but on topic for condenser mics.
CJ keep us in the loop on Ollie
I hope we do not loose him!
Those things are still not 100%
He is most knowledgeable on tubes for mics; on the planet that I know.
And gus wants to know!

 

[Plexibreath]

Do put up pictures of the BA6A. I've never used one but have heard great things about them. Where does it sit in a comparison with other classics like the LA2A, 1176, 660 and SSL?
Kelley

 

[Guest]

I have no experience with tube DIY, but for a RCA BA6A clone, I will jump head first. Every time I've used a BA6A it has brought a smile to my face.

I have have a press brake / shear on my shopping list with a desire to learn all things sheet metal. I might actually try to recreate the chassis as well. I've already learned that RCA used an "Umber" hammer toned paint for most of their "pro audio" equipment back in the day. As it happens Wes Dooley of AEA Associates, has a recreation of a RCA DX-77 and DX-44, which looks like the same finish as a BA6A. He is only about 2 miles away, so I would try to see if he has the same paint as the original. He also has recreation (old skhool) badges. RCA console knobs, forget about it, they're all over the internet.

If we could get the same kind of graphical wiring diagram as we had for the LA-2A, or the Pultec EPQ-1A, I would be a happy phuker.

This of course this is if we can successfully (CJ) reverse engineer the transformer.

Cheers,

elco
Mike Stromsoe< coming out of his shell.

 

[22busy]

Here's a try at posting some pics of the interstage tx. 'Hope it works cause this is the first time I've tried to set up a website and host photos.

BB


http://members.cox.net/22busy/RCA_BA6A/BA6A_IT1.jpg

http://members.cox.net/22busy/RCA_BA6A/BA6A_IT2.jpg

http://members.cox.net/22busy/RCA_BA6A/BA6A_IT3.jpg

 

[mcs]

It doesn't work. Add .jpg to the filenames and upload the files again.

It would also be better if you just inserted the links (remote the codes), as the photos are rather large.

Best regards,

Mikkel C. Simonsen

 

[gyraf]

You can copy/paste the links into your browser, and they'll work (at least with ie) or follow the link:

http://members.cox.net/22busy/RCA BA6A/BA6A_IT1

http://members.cox.net/22busy/RCA BA6A/BA6A_IT2

http://members.cox.net/22busy/RCA BA6A/BA6A_IT3

Jakob E.

 

[22busy]

I renamed the files so the links should work now. Thanks and sorry for the confusion.

Bruce

 

[mcs]

[quote author="gyraf"]You can copy/paste the links into your browser, and they'll work (at least with ie)[/quote]
If you use other browsers they are displayed as text though...

Best regards,

Mikkel C. Simonsen

 

[mcs]

Here is a set of working links for non-IE users:

http://stiftsbogtrykkeriet.dk/~mcs/BA6A_IT1.jpg
http://stiftsbogtrykkeriet.dk/~mcs/BA6A_IT2.jpg
http://stiftsbogtrykkeriet.dk/~mcs/BA6A_IT3.jpg

Best regards,

Mikkel C. Simonsen

 

[Winston OBoogie]

...

 

[22busy]

Glad you like the pics. Here's a few more. (this is getting addictive :grin: ) Please let me know if you're having trouble with these links cause I'm just trying to work out the kinks myself.

Bruce

http://members.cox.net/22busy/RCA_BA6A/BA6A_front.JPG
http://members.cox.net/22busy/RCA_BA6A/BA6A_rt_front.JPG
http://members.cox.net/22busy/RCA_BA6A/BA6A_top.JPG
http://members.cox.net/22busy/RCA_BA6A/BA6A_tray.JPG
http://members.cox.net/22busy/RCA_BA6A/BA6A_CATthode.JPG

 

[Winston OBoogie]

...

 

[22busy]

Oh !#$%, I know nothhhhhhhhhhhhhhhhhhing :shock: :roll: :wink:


Although, ........................ I do seem to remember some, er, stories (cough, cough) ........about this guy with a limey accent ...........................

 

[NewYorkDave]

I posted this back on RO a while ago; but for those who missed it the first time, here's an article about the BA6A I scanned from an old issue of Audio Engineering

900kB PDF File