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Graflarger Transformer Question

 
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Gammanine



Joined: 11 Aug 2001
Posts: 46
Location: Brooklyn NY

PostPosted: Sun Nov 07, 2004 11:52 pm    Post subject: Reply with quote

I'm breathing life back into a graflarger. After trying to build my own I had to admit defeat and buy one on the much beloved auction site. Aristo had quoted me a price on a new tube, and I'll get that this week. The transformer works, but the line cord to the "head" is sketchy and seemingly irreplaceable without messy R&R. So I'm looking around to replace the original with a new one. But I'm not sure of the output voltage. Anyone here have one they can test or maybe have a spec sheet on one? If not I'll attempt to "unpot' this one and have a go at replaceing the cable. Any and all tips appreciated. Thanks

[ This Message was edited by: Gammanine on 2004-11-07 15:54 ]
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RichS



Joined: 18 Oct 2001
Posts: 1467
Location: South of Rochester, NY

PostPosted: Mon Nov 08, 2004 2:58 am    Post subject: Reply with quote

I looked at mine, and spent an hour or so searching the net... No info that I could find... Sorry 'bout that...

I would suggest asking Aristo. They were very helpful when I bought my new tube, although I never thought of asking them about the transformer. They would obviously know the details of the voltage and current recommended for the tube. And I hope you got the V54 tube?

And a word of caution to anyone who may not think twice about opening up their graflarger to measure that output voltage. The tube is a neon light. Standard voltages for such light tubes run from 3,000 to 10,000 volts! Unless you have the specific high voltage measuriong equipment and are experienced at such things, DO NOT try to measure this voltage!
Said by someone who's been zapped too many times to remember....
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jdman



Joined: 13 May 2001
Posts: 302
Location: Midwest

PostPosted: Mon Nov 08, 2004 6:19 pm    Post subject: Reply with quote

With all due precautions a good device to measure the voltage would be a B&K high voltage probe. They will handle 30 to 40K with no problem. Used them for years when setting the high voltage on TV sets. Of course they may not be still available. Russ
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Gammanine



Joined: 11 Aug 2001
Posts: 46
Location: Brooklyn NY

PostPosted: Thu Nov 11, 2004 6:31 am    Post subject: Reply with quote

Yep, I got the V54 tube. Louise at Aristo gave me the heads up on it. She was unable to get me specs on the original transformer though. Fortunately, I found a solution. I emailed several people selling transformers on that famous auction site and told them all about my project. One cool guy came to the rescue. He actually sent me a transformer for free, just to test it out. (he thought my little project sounded cool).
What he sent me is a auto ranging 2kv to 6kv solid state transformer. It automatically senses the load and adjusts acoordingly. I hooked it up to the old tube and its working like a charm.
I've managed to extricate the core and windings from the original housing, That potting compound was tough as nails. But an hour of carefully prying and chipping away allowd me to get a hold of it and pull it out with brute force. I sure as hell hope that stuff isn't a pcb compound. Well, too late to sweat it now.
Now, If I can get the new transformer to fit in the original housing....... Now that would be something. hehe.

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RichS



Joined: 18 Oct 2001
Posts: 1467
Location: South of Rochester, NY

PostPosted: Thu Nov 11, 2004 6:47 am    Post subject: Reply with quote

That's good news, I hope

Does this mean you're putting the new auto-transformer into the graflarger case? Or are you still trying to fix the old transformaer?

Either way, a manufacturer and part number for that new transformer would be appreciated for anyone else who may need a replacement!

The potting is usually refered as some form of asphalt. This can dry hard as rock and was very common in transformer use way back when... It was usually(?) disolved in some pertroleum based solvent like kerosene or gasoline, but it taked days to soften (and of course is a bit dangerous). Some recommendation on unpotting old transformers included shorting the outputs to heat it up to soften the potting. I don't recommend that myself...

But out of curiosity, you could take some chips of the potting and soak them for a while in kero or gas to see if they would soften & melt. That might help future do-it-yourselfers too.

Ohhh, the responsibilities of being the first one to tackle such a job

Good luck and keep us posted!
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Gammanine



Joined: 11 Aug 2001
Posts: 46
Location: Brooklyn NY

PostPosted: Sat Nov 13, 2004 3:10 am    Post subject: Reply with quote

I read (on the web) about the various means to separate the transformer from the potting compound. Seems the sci/fi guys building jacobs ladders have lots of webspace devoted to transformer R&R. None of that was on my agenda. I'm not that motivated. I'm surprized that I found the energy to pull the old one apart. In doing so I hacked up the original coils assembly beyond repair. I knew I wasn't going to use it so I gave myself the freedom to be less than careful while prying and chipping away. In a strange way that event was sort of theraputic.
My plan is to try and fit the new variable transformer into the original graflex graflarger housing.
The unit is made by Marshall Electric. Item number 5197b.
Output is 2-6 kv. 30mA. input is 120V, 60hz, 1.5A.
Now, this has not been 'road tested". I have a ways to go before I get to actually give a performance report. But so far, its all good.
Ironically, its distributed out of Rochester.
Rochester, Indiana that is.
By the way, the tube came from Aristo this morning. Nice company to deal with. I should have this all together in a few days. I want to repaint the inside of the "head" before I reassemble it. No sense in cutting corners at this point.
Additional info on topic:
The guts of the new transformer are not able to be removed and installed in the old housing. Seems there is a small section of a potting compound in the works and I'm not going to screw up this transformer trying to retrofit it into the original graflarger housing. So I've reassembled the unit, having repainted the inside of the 'head' and wired up the transformer and the new Aristo tube. Everything went well, no problems. Its working perfectly. All I have to do is get a few trays out, mix some dektol and see what develops. hehe. I think this is the ticket. The new transformer weighs about 1 pound, much better to deal with than the old clunky one. Storing and maneuvering or traveling with this set up will be a breeze. The new tube is much brighter too. I'm not sure what to do with the old one though.

[ This Message was edited by: gammanine on 2004-11-13 17:23 ]
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Gammanine



Joined: 11 Aug 2001
Posts: 46
Location: Brooklyn NY

PostPosted: Tue Nov 16, 2004 2:35 am    Post subject: Reply with quote

More transformer info.
Since I really wanted to use the old housing, I kept looking for a coil/core transformer to fit inside of it. I've found one I think will do the job, and I may just pick it up and install it in the original graflarger transformer case.
I just cant bring myself to toss the old housing out just yet. If this pans out I'll post more info. Looks like the cost of this coil/core will be about 62.00. We'll see.
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