Spellman DXM70N600X3547 power supplies on ebay -70kV 8.56MA

This forum is for specialized infomation important to the construction and safe operation of the high voltage electrical supplies and related circuitry needed for fusor operation.
Cliff S
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Cliff S » Wed Nov 30, 2016 4:59 pm

To answer Andrews questions:

-15V: Uses a charge pump converter. See attached. Has a pretty high output impedance. Usually "-15V" can be in the -12.5- -14V range...ish.
See attached info on the other test commands.
Attachments
DXM Code Snippets.pdf
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+,-15V.pdf
(289.54 KiB) Downloaded 178 times
ICL7662-Si7661.pdf
(335.89 KiB) Downloaded 188 times

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Rich Feldman
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Rich Feldman » Wed Nov 30, 2016 9:06 pm

Hip, hip, hooray for Cliff. Very generous of you to share those official schematic pages. And the story about those pesky C149's. Good to know that my employer isn't the only one who sometimes traces reliability issues to product abuse by customers.

The charge pump IC for -15V reminds me of a new-ish class of components possibly handy in fusor labs. They're called photovoltaic MOSFET drivers, e.g. APV1121S or VOM1271. You put in about 10 mA and get an isolated DC source of more than 8 volts (with s/c current in the low microamp range). We have a design with 4 in series for 30 volt power to some "high voltage" CMOS analog switches. Might be handy for biasing certain radiation detectors whose average current is negligible.
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Dan Knapp
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Dan Knapp » Thu Dec 01, 2016 2:55 pm

Does anyone have a pin identification diagram for the CA11 connector? Does anyone know the derivation of the letter codes for the pins?

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Rich Feldman
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Rich Feldman » Thu Dec 01, 2016 3:12 pm

The C,S,G etc are named in DXM manual somewhere, maybe even on short brochure which gives pinouts of all connectors.
Left two terminals are internally connected, and right two terminals are connected.
If you aren't using the filament supply, any single pin could be used for HV. No practical difference which side you choose.
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Dan Knapp
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Dan Knapp » Thu Dec 01, 2016 3:33 pm

I couldn't find the pin identifications in the DXM manual nor in the documents on the Claymount web page. I know they're all connected in the DXM in regard to the HV, but some people are planning to power a filament with these supplies. Does anyone know the historical derivation of what the letters stand for?

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Rich Feldman
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Rich Feldman » Thu Dec 01, 2016 4:24 pm

Just learned that S and L are for Small and Large filaments, and C is the "HV output" according to http://vjv.linx.netdna-cdn.com/wp-conte ... VG223k.pdf .
Same here from Spellman, in brochure for a line of bigger power supplies:
xrv.JPG
Now when there are 4 terminals, what's the fourth one called?If the letter is G then I bet it's for Grid, aka focusing cup or Wehnelt electrode. Okonite, a cable mfg, says:
Cable Core: Each Low Noise cable core contains two insulated filament conductor. In 65, 75, and 100kV cable filament conductors are #15 AWG (19x) [1.65mm2] tinned copper insulated with heat sealed color coded polyester tape. ...
Four conductor cables include one #20 AWG (7x) [0.52mm2] copperweld conductor per ASTM B-45 insulated with heat sealed polyester and shielded with metalized red polyester.


[edit] OK, my money is down on the table.
Small filament
Large filament
Common to both filaments
Grid -- for beam focus, could be 100 or 200 V more negative than the filaments.

From an early post by Andrew S:
lcsg.JPG
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Dan Knapp
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Dan Knapp » Thu Dec 01, 2016 9:02 pm

The CA11 pin list from the DXM data sheet is reproduced below along with the wiring diagram from the DXM manual. They recommend a Claymount L3 cable as listed, but it seems strange to state that the "bare shield wire" would be connected to the high voltage. I think they must be referring to the bare inner wire which is one of the three conductors and not to the outer braided shield. I checked an old full size federal connector (3 pin) cable I have, and the braided outer shield is indeed connected to the chassis ground part of the plug as one would expect, with one of the three pins connected to the bare wire inner conductor. It must be part of the X-ray cable jargon to refer to the bare inner conductor as the "bare shield wire."
I still have found no diagram that identifies the positions of the C, S, L, and G pins on the CA11 connector; i.e. the relation between the 1,2,3,4 on the drawing below and C,S,L,G.
Attachments
CA11 pins.pdf
diagram of the CA11 pins
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Claymount L3 cable.pdf
Claymount L3 cable
(75.45 KiB) Downloaded 157 times
DXM-Neg output.pdf
CA11 connections on the DXM
(79.04 KiB) Downloaded 188 times
CA11 on DXM.pdf
CA11 pin list from DXM data sheet
(114.69 KiB) Downloaded 149 times

Dan Knapp
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Dan Knapp » Thu Dec 01, 2016 9:08 pm

I just looked again at Andrew's connector photo and noticed that he has the pins marked (the old eyes aren't what they used to be). So relating this to my drawing of the "CA11 socket":
1 = L
2 = G
3 = S
4 = C

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Rich Feldman
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Rich Feldman » Fri Dec 02, 2016 2:26 am

Looks good, but I'd number the pins differently. Here's my take on it:
csgl.JPG
A convention has persisted since vacuum tubes, including IC's in TO-cans, DIPs, etc., even modern packages smaller than vacuum tube pin diameters.
Pin numbering runs clockwise when viewing a socket from the wiring side, or a removable part from the pins side.
Counterclockwise when looking at a socket from the user side.
untiny.JPG
tiny.JPG
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Jim Kovalchick
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Jim Kovalchick » Fri Dec 02, 2016 10:04 pm

Ran Andrew's DXM test on my unit. The xray on light comes on momentarily followed by the over voltage light. Any ideas?

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