JRE Productions

API tranformer question for the GURU's.....API 2517
« on: March 28, 2006, 12:51:21 AM »
I am having a ton of fun with the transformer kits I got. THANKS!  I have learned alot on constructions and ran into a strange bird...


In an API 575 module (tone Oscilator), there was a output transformer that I removed. It is numbered API 2517. It is smaller than the 2503 and has 3 windings.  Two windings measure 25 ohms and one measures 16 ohms.  Which would be primary?  For a preamp. would I have to place a pair windings in series for some gain?

The color on the wires are strange too. One pair is blue/white white/blue. One is Red and Brown. and the last White/brown and grey.  Not sure how to tell the Hi side of each coil.

Also when I checked my transformer kit, all the coils measured 14 ohms. But CJ mentioned the primary is 75 ohms, and the secondary is 600 ohms. How does this work?


Thanks,

Joe


JRE Productions

API tranformer question for the GURU's.....API 2517
« Reply #1 on: March 28, 2006, 02:12:48 AM »
Sorry the number is 2157. And I am certain I am confused on more than what you stated. But hey, if thats all you have caught me with for now, I am ok with that!


JRE Productions

API tranformer question for the GURU's.....API 2517
« Reply #2 on: March 28, 2006, 01:30:46 PM »
maybe CJ can sort some of this out....

CJ

API tranformer question for the GURU's.....API 2517
« Reply #3 on: March 28, 2006, 02:57:20 PM »
Do you have the circuit for that thing?

It's an output. We know that.
But that's about it.

Ohms seem like 2503 only twice as much.
Transitor to line I am guessing.
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

JRE Productions

API tranformer question for the GURU's.....API 2517
« Reply #4 on: March 28, 2006, 03:45:19 PM »
It was driven by two 2520 opamps:




Some one mentioned that they used the same one for a preamp. That is what I was thinking too...

Joe

CJ

API tranformer question for the GURU's.....API 2517
« Reply #5 on: March 28, 2006, 03:51:25 PM »
See if you can see the winding structure or wire thru the bobbin.
Hold it up to a brite lite.
Is it multi strand mag wire?
If I can't fix it, I can fix it so nobody else can!
Frank's Tube Page: www.mif.pg.gda.pl/homepages/frank/vs.html
Guitar Amps: http://bmamps.com/Tech_sch.html

Family Hoof

API tranformer question for the GURU's.....API 2517
« Reply #6 on: March 28, 2006, 11:30:08 PM »
We know it's a smaller-sized output transformer (so less headroom than the 2503) and we also know that API used a number of presumably similar small transformers in their console routing modules and other less important, more utilitarian applications - like that osciallator for example - so there's nothing stopping you from using as the output of your preamp. If you have the oscialator that it came out of you should be able to visually trace the circuit and see how it was hooked up to the 2520. This will clue you as to which winding is the primary and which wire is the start of the winding. I will check the schematics and affirm when I get the chance, it just didn't happen today.

JRE Productions

API tranformer question for the GURU's.....API 2517
« Reply #7 on: March 29, 2006, 01:40:45 AM »
Well it appears that I can wire it for 1:2 with no problem. I will give it a shot with audio next.

JRE Productions

API tranformer question for the GURU's.....API 2517
« Reply #8 on: March 29, 2006, 10:13:34 AM »
It appears that the 16 ohm coil was the primary, and the two 25 ohms coils were the secondaies. I sent a signal into the primary and both secondaries look to be a 1:1 ration of the primary. Nice clean output on each. I placed the secondaries in series and had a beautifull looking 1:2 ratio signal on the scope.

I don't know what that means as far as source and output impediance. I  will probably drop this into a 325 card and see what she does. I have a test box set up for 325 cards, so once connected up, it should be plug and play to test.  Eventually I want to use this in a preamp, but my first need is to use it as a test fixture for all these 2520 opamps I built. So the card is going to have sockets for the 2520...

CJ,

The best I can tell holding this to the light is that the wire is the same color as your kits. I could not tell what the actually winding looked like. The bobbin is smaller and also the lambs.

Joe

Family Hoof

API tranformer question for the GURU's.....API 2517
« Reply #9 on: March 29, 2006, 11:58:26 AM »
According to 575 schematic...

2157

primary hi = RED
primary lo = RED/YEL

secondary hi = BRN
secondary CT = BRN/YEL tied to BLU
secondary lo = BLU/YEL

Oh, and it IS one of the little ones found on router modules. I knew I'd seen this guy before. I'll check for Litz tomorrow, CJ.


JRE Productions

API tranformer question for the GURU's.....API 2517
« Reply #10 on: March 29, 2006, 12:13:50 PM »
Thanks! That is awesome. I will have to go back to the shop and see if that is how I connected it up....


 

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