Looking for information on a Presto 900A3 preamp?

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Looking for information on a Presto 900A3 preamp?

Unread postby gmrgtrs » Fri Apr 07, 2017 8:55 am

Hello all,

I just joined these message boards, and I've just posted my formal introduction and am happy to be here, and wondering if anyone might have some input or advice for me.

I am starting to look into what will be necessary to restore a lovely looking Presto 900A3 preamp that belongs to a friend of mine, and wondering if anyone has any information on these units specifically? It looks to be in mostly original condition, but there has been a little bit of (obvious) work done here and there. It needs a power supply, and the inputs and outputs have been cut off and need to be rationalized somehow. I contacted Alan Graves (from the Presto History website) and he was kind enough to furnish a schematic for the 900A4, and a 900A1 PSU. On initial inspection what I have looks pretty close to the schematic I've got, but if anyone had a schematic or other literature that was specifically for the A3, and wouldn't mind sharing, it would be most appreciated! Also, if anyone happens to have any other information or experience with these units, it would be great to know, and make your acquaintance.

thanks!
gmrgtrs
 
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Re: Looking for information on a Presto 900A3 preamp?

Unread postby gmrgtrs » Fri Apr 21, 2017 9:08 am

Since my last post, I've done some further investigating into my preamp, and have found that unfortunately one of the two output transformers has an open winding. Does anyone have any experience either a) finding replacements for the UTC transformers used by Presto or b) getting transformers rewound? The output transformer code is F-8603, but based on some old UTC catalogs I've seen floating around the internet, it doesn't really look like a UTC code. Any ideas?
gmrgtrs
 
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Re: Looking for information on a Presto 900A3 preamp?

Unread postby markrob » Fri Apr 21, 2017 4:13 pm

Hi,

Have you looked at Hammond Mfg?

http://www.hammondmfg.com/1650p.htm

They might get you in the ballpark.

Mark
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