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.
Andrew Seltzman
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Andrew Seltzman »

I finished the HV cable for the supply
SAM_5467.JPG
SAM_5466.JPG
and have successfully tested with plasma and a neutron output
SAM_5465.JPG
At 45kV, 8.56ma about 1.5e6 n/s
neutrons-45kv-1,5e6.jpg
At 50kV, 8.56ma about 1.8e6 n/s
neutrons-50kv-1,8e6.jpg
Some notes about operating the supply on a fusor:
The supply does have an arc fault protection system that is fairly sensitive, when triggered it will momentarily reduce output voltage and then bring it back up to the set point. After a certain number of arcs in a given time window(about 5 arcs in a few sec) it will shut off the power supply. This does not present a problem with an occasional grid arc on a well conditioned grid, but is an issue with charge buildup on the surface of an unshielded HV cable(like the silicon one I have built). As the charge builds up on the outer surface of the insulating cable it will be attracted to a conductor and discharge, causing the arc fault to reduce voltage, this will cause the cable to pull away from the conductor and then attract once HV is re-applies causing another discharge. This repeated mechanical oscillation of the cable will trip the arc fault circuit.

Arc fault trip due to repeated static discharges from cable
neutrons-50kv-corona-fault.jpg
The HV cable will need a shield to prevent this effect, and possibly a semiconductive anti-corona tape layer between the silicon cable and the shield before higher voltages are attempted. Other then this effect, the supply operates very stably with a fusor and should help most people significantly increase their neutron output.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Dan Knapp »

Has anyone been able to figure out the login and password for the Spellman interface at 192.168.1.4?
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Dan Knapp »

To answer my own question, after overlooking it multiple times, I found the login and password on p. 15 of the DXM Digital Interface Manual: username: admin, password: SHV_Applet.
These worked on my DXM using Internet Explorer on an old laptop running XP. I was able to access the Web Monitor and Control Applet and read the hours meter. My unit reads 173.1 hours.
With a high voltage probe inserted into the CA11 receptacle and the enable pins 11 and 12, and 12 and 15 on J2 connected, I can step up the voltage using the web interface. Starting at 1000V, I get the right voltage on the output and can step up to 1400 volts in 100 volt increments with the correct output voltage. The current setting was 0 ma; with the current set to 1 ma, I get an "under current" fault both on the web interface and the front panel LED. When I try anything over 1400 volts, I get an "under voltage" fault both on the web interface and on the front panel LED.
Trying Andrew's standalone Matlab program, it starts scanning and fails the same way. I've not yet been able to get Andrew's DXM Control2 program to run under Matlab, possibly because I'm running a 2011 versionof Matlab whereas Andrew is using a 2016 version of Matlab.
I am unable to get any output using the analog control inputs via J2. This is perhaps a clue to where the fault lies.
At this point, my DXM is close enough to running that I think I'll keep it and continue to play with it.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Sarvesh Sadana »

After connecting pins 11 and 12 on the J2 connector, the interlock closed and I was able to enable the high voltage.

Despite that, I still got a message stating that my DXM is incorrectly configured, and I was not able to set the voltage or current. What am I doing wrong here?
IMG_0351.PNG
Also, has anyone made any further progress regarding the group purchase of the HV connectors and cables? I'd much rather buy one than try my hand at making it.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Dan Knapp »

Sarvesh
Have you tried connecting pins 12 and 15? Pin 15 is a second interlock on this version of the DXM (see Andrew Seltzmann's post).
Have you logged in to the web interface? Login: admin, Password: SHV_Applet
Are you getting the "x-ray on" LED on the DXM?
Your post gave me a clue to my problem. You are showing a reading on the "LVPS-15V" where mine is showing zero. I'll try to check the 15V power supply.
Keep sharing; between the various owners of the two dozen supplies maybe we can turn up enough clues to make them all work.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Andrew Seltzman »

As preventative maintenance, I replaced the C149 electrolytic capacitor on both supplies. One had started to bulge and the other has leaked a little out the top. The replacement was(thanks to Peter Schmelcher for finding a better version of the cap):
http://www.digikey.com/product-detail/e ... ND/1246008
SAM_5475.JPG
During the upgrade I also noticed that come of the 450V capacitor pins on the bottom of the board were beginning to rub through the plastic insulating sheet. If these do puncture the sheet they may short with the grounded insulating frame.
SAM_5468.JPG
SAM_5469.JPG
These areas were reinforced with kapton insulating tape, and the pins were trimmed a little closer to the board, and the solder balls rounded a little more. Everyone with a short in their supply should check these. In addition I added some heatsink compound to the rectifier to make better thermal contact with the frame.

Additional pictures of the bottom of the board:
SAM_5472.JPG
SAM_5474.JPG
After the modifications both supplies were tested with the dummy plug to 70kV without any problem.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Richard Hull »

Andrew nailed it and proved the supply can work in a good fusor provided the arc fault cutoff is properly handled. He climbed higher on the cross sectional curve via voltage. This curve is rather steep up to a little over 100kv, (get more bang - fusion- for increased voltage). Few are the folks who have drifted over the 40kv applied mark. I can get to 1.5e6 n/s sec, but I am at the limit of both my X-ray supply and the fusor insulator at about 43 kv where I hit that high neutron mark. There is negligble boost in fusion in going to 200kv applied as the curve flattens quickly

Andrew, can you report on the x-radiation at those higher voltages? The shell starts to go transparent at about 35kv applied and at 41kv, I am getting about 100mrem/hr at the glass view port, but at the shell, up close, the fusor only puts out about 20mrem/hr At 6-7 feet from the shell it is down to 1or 2mrem/hr and during a normal run will not effctively move my 100mr pen dosimeter off zero at that range.

I would imagine at 50kv applied the shell, acting as a filter shoots out only the most penetrating x-rays which are only a small portion of the x-radiation produced by the fusor, (and trapped in it). The x-ray energy at 50 kev applied only has a tiny fraction at that energy level.

To others here with these wonderments, Andrew's setup can handle the higher end voltages..... Can yours? Most fusioneers fall a bit short in their insulators. Of course, you need not run this supply full out, voltage wise. Most will discover their "rope limit." I know mine and it is about 43kv applied.

Richard Hull
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Fusion is the energy of the future....and it always will be
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Andrew Seltzman »

I modified my cable with some resistive anti-corona tape salvaged from another HV cable and some braided shield, this improved the tolerance to arc faults, but it still is a problem over 50kV.

X-ray rates were measured ~1ft from the fusor, my system has a 1/8" thick stainless shell, the view port has a 1/4" thick lead glass shield.
40kv <1mrem/h
45kv 5mrem/h 1e6n/s
50kv 15mrem/h 1.2e6n/s
55kv 50mrem/h 1.8e6n/s
Brief operation at 60kV possible before the arc fault system tripped, but not enough to to get a measurement. These were brief runs with minimal prior conditioning and no optimization of pressure / ion source tuning to get maximum neutron output. The runs were at 8.56mA current.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Richard Hull »

Thanks Andrew, That is good data and shows how the shell gets real transparent real quick with increasing voltages. As I have noted many times over the years. You do not have to shield for neutrons. Shield for X-rays!....And then only if you are wandering over the 35kv mark in an SS chamber of normal .0625 inch thickness. Andrew had double that thickness which is rather unusually thick for a fusor and his x-ray really shined through over 50 kv applied.

Note: normal, inexpensive, spun SS hemispheres are all .0625 inch thick. .125 inch is rather rare

Richard Hull
Progress may have been a good thing once, but it just went on too long. - Yogi Berra
Fusion is the energy of the future....and it always will be
The more complex the idea put forward by the poor amateur, the more likely it will never see embodiment
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Andrew Seltzman »

Does anyone know a distributor for an impregnated polyester anti-corona tape like this:
http://www.dexlu.com/woven-tape/anti-corona-tape.html
or something like it?

3m makes semi-conducting tape for field grading on the ends on HV conductors:
http://www.ebay.com/itm/NEW-Scotch-3M-E ... SwhcJWO5Br

But I can't seem to locate a distributor for resistive tape.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Rich Feldman »

I found C149 and CR34 both shorted. With those parts out, the DXM70 board DC rails are no longer shorted. Haven't yet installed replacements. For use exclusively on nominal 120 VAC mains, does anyone think the boards need or benefit from 450 volt rated capacitors?

The offending capacitor from my board doesn't appear to have bulged or leaked. Smoking gun was toasted FR-4 around the diode attachment holes. Sometimes that happens on working designs that have poor cooling or insufficient component derating.
dxm_bot_detail.JPG
That's a little snip from a full-board pdf file off a flatbed scanner, here in case anyone wants to carry on with reverse engineering.
dxm70_bot.pdf
(112.54 KiB) Downloaded 501 times
I experimented with Visio as a tool for reverse engineering. Took the flatbed scan and overlaid circles and rectangles, keyed by color, on various layers. Looks promising, and I already learned some practical details of half-bridge drivers etc.
dxm_overlay.JPG
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Andrew Seltzman »

The supply uses a PFC/boost converter system which increases the voltage to a few hundred volts, so the 450V cap is required.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Andrew Seltzman »

Here are 2 good references:

Spellman power supply reference
http://www.spellmanhv.com/-/media/Files ... manual.pdf

How to terminate cables for low corona/leakage
http://www.spellmanhv.com/Technical-Res ... age-Cables
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Rich Feldman »

Those are great references, Andrew. Thanks for the pointers.

Speaking of group buys, how about some repair kits with the nickel-and-dime components that many of us found dead? If you have to order an individual item by mail, you can buy ten for about the same total money (after shipping charge).

As Peter said a while back, "The supply is conservatively laid out and the RTV is a good indication of vibration testing for harsh industrial environments. Honestly it would be a pleasure to work on if I had a schematic. So it’s just finding the hours to do a methodical investigation/repair with a budget of $100 for parts."

I don't think Cliff would mind if we continue to share notes about the bill of materials, and sourcing of replacement parts. Here's a piece of a schematic learned by inspection, as others here have done. So far un-reviewed.
h_bridge1.JPG
Who wants to draw the power path from AC input through PFC circuit (Q10 and Q6), so we can see if it matches my scribbles? Can't see the label on my RV2 without removing the part, which measures about 24 ohms at room temperature. Can't see the label (or even the ref des) of rectangular pink capacitor next to the main bridge rectifier.

Almost forgot to mention, I made a DC resistance model of the whole interface coming up from the DXM70N's basement level. If the fancy inverter and control board were totally dead, or missing, why not use the potted "basement unit" to make a dumb HV supply, substantially derated of course?
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Liam David »

I replaced the blown IRFBG30 mosfet on my power supply board, but it still does not function. I checked all of the capacitors, and C149 has a slight bulge but has no continuity. Otherwise none of the components on the board appear damaged. Removing the fan revealed that there is only about 2V on the bus, which I assume should be 24V. Any ideas what could be causing this problem? Some kind of bad voltage regulator? All six red warning lights on the front panel light up and blink repeatedly, so some power is going somewhere.
The other supply functions properly and I was able to turn the voltage up to 28kV. Still working on making a CA11 connector.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Cliff S »

Hey guys,
A few have emailed me on this one...

...I feel your pain on this...attached are a few sheets of the power section schematic. Below is copied from what I have been telling a few of you that have emailed me directly:

Re: C149: There is a history on this parts failure mode: It had to do with some applications, when keeping the DXM in standby, at elevated temps. I don't recall the details off the top of my head...but it had something to do with the PFC hiccupping at light loads, causing high ripple on the cap. Under elevated temps, and after years of operation, it would fail. I think you can replace it with a similar rated part, and in your application it will probably be fine.

I do see that many fusor guys have these DXM's off of eBay....a flurry of posts in the past week. This specific model X# has a particularly sorted past... to date we have shipped over 1,000 of these units to one customer for their food inspection system. We have wrestled with reliability issues early in the program due to our customer using these in a inadequately cooled cabinet. Ambient temperatures far exceeded the ratings of the supply. My guess is the customer has replaced many of the units in the field, and you guys are seeing these used, replaced units. Failures tending to be around the power semi's and in the HV section. (Some ceramic HV caps do not like high temps).

Your “X3547” l unit has some differences from the standard interface:

High Voltage Interlock: Pin 11 on J2 is the H.V. interlock in both local and remote mode. The hardware based dry contact closure must be closed in order to enable the high voltage via J2-15 in local mode or USB, Ethernet or RS232 mode. This can be done by connecting pins 11 and 12 on J2. The interlock must be closed prior to the unit being enabled. If the interlock is open and closed while the unit is enabled, the enable will need to be re-asserted to generate high voltage.

High Voltage Enable: Pin 15 of J2 is the H.V. enable for the local mode only. The hardware based dry contact closure must be closed to enable the high voltage. This can be done by connecting pins 12 and 15 of J2. This I/O is disregarded in remote mode.

Good Luck. Be safe.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Andrew Seltzman »

Cliff, thanks again for the continued help you provide to the fusor.net community, I'm sure those pages will help a number of people debug their supplies. By the way, what is the -15v LVPS variable and what should it's normal value be(is this just the -15v DC bus voltage)? The manual also specifies that there are some test commands that you can send the supply, could you provide us with the syntax for these?
6.7 SPELLMAN TEST COMMANDS
 Program Hardware Version (Hardware setup)
 Program Model number(Hardware setup)
 Set USB Mode (Program USB)
 Set USB Page Address (Program USB)
 Send USB Page Data (Program USB)
 Toggle Passthrough Mode (Diagnostics)
 Store A/D Calibration Value (Hardware setup)
 Request Miscellaneous Analog Readbacks
Contact Spellman High Voltage for details and the syntax of these
commands.
Liam,
The IRFBG30 mosfet is part of a flyback converter that generates the 24V(first page of the schematic Cliff posted) that then is regulated down to all the lower voltages the supply requires. If you apply 24V to the fan connector this should power up all the digital circuitry/Ethernet interface for testing. If there is 2V on the fan connector when the supply plugged in I would suspect a problem in this flyback converter.
The converter draws power off of C149, what voltage do you have across this capacitor when the supply is plugged in?
Is the transformer primary ok(pins 3-4 on T2)?
Diode CR34 feeds voltage to C149, is the diode ok?
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Liam David »

I applied 24V to the fan connector and the digital circuitry came on with a green system power light. This narrows the problem down to the converter. C149 has about 120V across it, diode CR34 is good, and the transformer T2 appears intact. Both secondary coils do have continuity between them, but I would assume this is because of other components. My suspicion would be that the UC3845 chip or the CL70 NTC thermistor is bad.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Andrew Seltzman »

Check R206, if it is open the mosfet won't be sinking any current to ground.
Also check for an open in the traces between C149 positive and pin 4 of T2, the trace between pin3 of T2 and the mosfet, and the trace from the mosfet to R206.
Check voltage on pin7 of UC3845, it should be bootstrapped by the R192,R200,R197 resistor chain even if the boost converter is not working.

Does a relay click when you plug it in?
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Liam David »

The relay does click when I plug it in. I will update this post tomorrow when I check the other components you listed.
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Re: Spellman DXM70N600X3547 power supplies on ebay -70kV 8.5

Post by Cliff S »

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

Post by Rich Feldman »

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

Post by Dan Knapp »

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

Post by Rich Feldman »

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

Post by Dan Knapp »

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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