low voltage power transformer - case standards?

by **a.d.a.m. baby** » Tue Sep 06, 2011 10:56 am

One of the secondaries in the PSU transformer in my TR909 has failed. The case bolts on to the chassis and is the support for the PSU PCB, so getting a similar physical unit is important. Roland no longer have any spares (can't understand it! - it's only 30 years old!).
My question is, is there a standard casing system with these things like there is for ICs and transistors? Or is it just, measure it up, and good luck?

cheers
Adam

by **rob** » Tue Sep 06, 2011 3:09 pm

measure it up, find something with the correct secondaries then scratch your head on how to mount it in there. As a broad generalisation something with the same amount of iron in it will be of the same wattage.

by **Thirteen** » Tue Sep 06, 2011 6:50 pm

Which secondary winding has failed? It has a centre tapped winding for the +/- 15V analog supply and a single winding for the 5V digital supply.

by **a.d.a.m. baby** » Tue Sep 06, 2011 7:01 pm

Thanks Rob and Steve.

The 9.5 secondary for the 5v supply has gone.

Its rated 17VA, but next to this says 15V as well..??
Anyway near enough should be good enough, but getting the physical size to match for the reasons I mentioned will be more critical due to the tight space.

cheers
Adam

by **Thirteen** » Tue Sep 06, 2011 7:04 pm

I will take a look tomorrow and see if i have anything that will fit.

by **a.d.a.m. baby** » Tue Sep 06, 2011 7:48 pm

Steve I really appreciate it, many thanks

Adam

by **Thirteen** » Tue Sep 06, 2011 10:17 pm

What is the code number on the transformer? Is it a Bando?

by **a.d.a.m. baby** » Wed Sep 07, 2011 4:11 pm

It says "TAM E57-3PD/30" moulded into the plastic base. A sticker on it elsewhere says "245-364U" with "3L102" beneath this.
On the schematic (page 12 of the SM) the unit is referred to by the "245-364U" code.

cheers

by **a.d.a.m. baby** » Thu Oct 06, 2011 2:59 pm

I must not be using the correct terminology - I can't seem to find anything close to what I'm after on the web. I would've thought there would be a stack of transformer options for a supply that is required to give +/-15 and +5 volts.
Any suggestions? Preferably from Australia but not critical....

by **Thirteen** » Thu Oct 06, 2011 3:13 pm

Sorry, I forgot about your transformer. I have a whole bunch of transformers with +/- 15 and +5 taps, I bought as many as I could from Roland some time ago because they are becoming so hard to find, and every brand of digital analog hybrid synth over the last 25 years uses them and I am always looking for them. I doubt that I have the specific transformer from the 909, but I may have something that fits. I will look on the weekend, sorry I forgot to look for you before!

by **a.d.a.m. baby** » Thu Oct 06, 2011 5:22 pm

Thanks Steve. If you've got one that is chassis-mount with holes at 72mm (2 13/16 in.) I'm sure near enough will be good enough..

by **a.d.a.m. baby** » Mon Oct 17, 2011 6:11 pm

I've had a couple of suggestions:

1) Get the transformer rewound (apparently this is not too uncommon? - I was surprised)

2) Use toroids, as shown here...

http://www.colinfraser.com/tr909/909psu1.jpg
http://www.colinfraser.com/tr909/909psu2.jpg

Someone (in the UK) suggested I could get a custom toroid wound to my specifications for a reasonable price, which would save even more space and trouble (again - I was very surprised).

Does anyone have any suggestions for "local" businesses that do the above work?

by **Gian** » Mon Oct 17, 2011 6:41 pm

I get custom toroids wound for me all the time. I use harbuch. Just ring Peter and tell him what you need. He is very helpful.

http://www.harbuch.com.au/

by **Thirteen** » Mon Oct 17, 2011 7:51 pm

I have found a couple of transformers that might fit, I need a 909 to se if they will go onto the board... It's a pretty tight fit from memory.

by **a.d.a.m. baby** » Mon Oct 17, 2011 9:02 pm

Gian wrote:I get custom toroids wound for me all the time. I use harbuch. Just ring Peter and tell him what you need. He is very helpful.

http://www.harbuch.com.au/

That's good to know, thanks Gian

Thirteen wrote:I have found a couple of transformers that might fit, I need a 909 to se if they will go onto the board... It's a pretty tight fit from memory.

Exactly, a very tight fit. Those photos show the 909 board "before and after" the toroids. The transformer mount plate is 83mm wide with 72 mm between the mount hole centres. The height off the PCB needs to be not much more than 60mm. If you think you have something close PM me, thanks Steve

by **a.d.a.m. baby** » Mon Dec 05, 2011 6:35 pm

Good outcome. As it happened, I found a local business (Gold Coast) that specialises in transformer winding and re-winding. Gary Hjort from Transformers and Coils Australia did a great job, preserving the mounting bar and the pin-out, saving me heaps of trouble - parts and labour all up $118.00

Now, what was I doing again....?

low voltage power transformer - case standards?

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