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 Post subject: Universal Electronic power supply
PostPosted: Apr Mon 28, 2003 9:38 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 41
Location: Maine, USA
I own an older regulated power supply for tube work which was built by Universal Electronics in Santa Monica, probably in the 60s. The Model is 425A.<P>I am looking for any info or schematic for this model.<P>TIA O.<P>------------------<BR>


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 Post subject: Universal Electronic power supply
PostPosted: Apr Wed 30, 2003 9:33 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3162
Location: Cockatoo, Victoria, Australia
You haven't been swamped with replies. What tubes does it use and what are the voltage and current ratings of its output(s)? What problems do you have?<BR>Don Black.<P>------------------<BR>


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 Post subject: Universal Electronic power supply
PostPosted: May Thu 01, 2003 4:20 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 41
Location: Maine, USA
No Don, no overload of information yet.<P>The unit has 8 tubes, 5R4GYB, three of 5881, one tube with no markings, 0D3, 6SH7 and 6SN7GTB. <BR>It supplies filament voltages up to 8 amps, high voltage up to 400 volts and 250 mA and bias voltages up to 150 volts.<P>There is no problem with the unit right now except for the occasional bad contact here and there. There is a modification somebody did, I don't know what for, I don't know what it does and my inquiery is basically a long term wish to have all the docs with the unit so it can be maintained. <BR>The meters will need to be calibrated.<P>As you can see it might really be a longterm goal, nobody has ever heard of this unit, even though it appears to be a well made, substantial piece of equipment. Too bad I can't add a pic (no attachments here?), you would see what I mean.<P>Best regards Uwe<P>------------------<BR>


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 Post subject: Universal Electronic power supply
PostPosted: May Thu 01, 2003 5:47 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 12268
Location: Mpls, Minnesota
Are you sure this is a power supply and not an amp?? You can post a jpg picture in the picture gallery<P>Dave<P>------------------<BR>


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 Post subject: Universal Electronic power supply
PostPosted: May Thu 01, 2003 7:17 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 37189
Location: Livermore, CA
Hi<P> Might be a series regulated supply with 5881's in parallel? Reasonable for the 0D3 to be a reference, controlling 6SH7, going to grid of 5881's. <P> Check Radio Amateur Handbooks from late 50's or 60's. They had similar circuits but using a 6AS7G instead of 5881's. Your tubes can supply higher voltage. <P>------------------<BR>Norm


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 Post subject: Universal Electronic power supply
PostPosted: May Thu 01, 2003 8:36 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 41
Location: Maine, USA
I just posted a pic but I am not sure about the results, the upload goes well but then I cannot see the picture myself afterwards!?!<P>You tell me<P>Uwe<P>------------------<BR>


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 Post subject: Universal Electronic power supply
PostPosted: May Thu 01, 2003 1:13 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 3162
Location: Cockatoo, Victoria, Australia
Hi Uwe, I can't see the pictures either. The most common problem is having spaces in the file name. That's a substantial supply, very nice to have on the bench. I haven't found anything yet but I'll keep looking. Does it say where it's made (USA or imported)? Does the unmarked tube have a glow inside? It might be a voltage regulator.<BR>Don Black.<P>------------------<BR>


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 Post subject: Universal Electronic power supply
PostPosted: May Thu 01, 2003 8:19 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 30698
Location: Pocasset, Cape Cod, MA
Never heard of this particular maker, but it's a common tube lineup for about 1950. You're missing the second rectifier, so the mystery tube could be a 5Y3. Kepco made a supply like that. Since Santa Monica already had the Douglas Aircraft Co. there were plenty of technical people around, and a ready market for such things. I've had to trace circuits myself for a couple of supplies of that vintage.<P>------------------<BR>


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 Post subject: Universal Electronic power supply
PostPosted: May Fri 02, 2003 5:25 pm 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 30698
Location: Pocasset, Cape Cod, MA
Pretty. You can find date codes on the tubes, electrolytics, pots and perhaps other components.<P>------------------<BR>


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 Post subject: Universal Electronic power supply
PostPosted: May Fri 02, 2003 7:00 pm 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 41
Location: Maine, USA
Date codes?<BR>I don't know about those.<P>The only dated info is the calibration sticker, apparently in 1974 this was still in service.<P>Uwe<P>------------------<BR>


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 Post subject: Universal Electronic power supply
PostPosted: May Sun 04, 2003 4:06 am 
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Joined: Jan Thu 01, 1970 1:00 am
Posts: 974
On a 1946-1960 unit, look for 6-digit EIA (Electronic Industries Association) date codes on the pots, electrolytics and transformers. The first three digits denote the part maker, the 4th digit is the last digit of the year, and the last two digits are the week of the year. After 1960, 7-digit codes were used, the 4th and 5th digits denoting the year. For more information, Google "EIA" and "date code". <P>------------------<BR><BR>


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 Post subject: Universal Electronic power supply
PostPosted: May Sun 04, 2003 4:19 am 
Member

Joined: Jan Thu 01, 1970 1:00 am
Posts: 30698
Location: Pocasset, Cape Cod, MA
And tube codes are in Lud Sibley's book "Tube Lore."<P>So Ted, I didn't see you at Hoss Traders today. Not that you missed a lot, but I sold some junk, bought new toys, and came back with more money than I left with.<P>Couldn't pass up an H-P 122A scope in absolutely mint shape, always stored in a padded wooden case custom-made for it. Seller wanted $10 for the box, scope was free. Also got a school-lab VOM demonstrator made by Welch. Schematic silk-screened on the panel. That one was literally free.<P>------------------<BR>


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