Spellman XLF mystery malfunction

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George Ressinger
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Spellman XLF mystery malfunction

Post by George Ressinger »

I've restored a spellman XLF 30kv 30 ma power supply from not turning on at all to lighting up and partially functioning.

however, when i turn it on, the "HV OFF" light the manual claims should be illuminated doesn't turn on. when i depress it, as the procedure states, only the voltage display reacts, but I am unable to change it with the pots.

the original problem was a disconnected thermistor on one of the boards, but I don't currently see any other loose bits, and all wires seem to be connected.

has anybody encountered this before, or have any thoughts on what the problem might be/how to fix it?

just thought I'd ask before I start really digging into it.

thanks,
George
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Richard Hull
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Re: Spellman XLF mystery malfunction

Post by Richard Hull »

Can you raise the voltage on the voltage adjustment pot on the front panel?

I imagine the lamps are LED and not incandescent. In the old universal voltronics supplies if either the HV off or the HV on incandescents were burned out the supply would not function. That was a great way to avoid dangerous conditions, (no indication of on or off HV on the supply). Incandescents might still have a place in such instances. Universal Voltronics routed the on-off relay power through the lamps. No good lamps would allow no main relay latch action.


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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Steven Sesselmann
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Re: Spellman XLF mystery malfunction

Post by Steven Sesselmann »

George,

Does it have the terminals at the back for remote control?

If so the voltage and current terminals need to be shorted for the front control knobs to work.

PS: and the interlock as well.

Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG
George Ressinger
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Re: Spellman XLF mystery malfunction

Post by George Ressinger »

Thanks for the tips, I'd already set up the interlock, but the HV return worked perfectly. the power supply now supplies power.

however, I am unable to adjust either the voltage or current as the procedure instructs. the pots seem to do absolutely nothing. it runs at an arbitrary voltage of -1.7 KV and a current of 12.7 ma, with the interlock closed and output current being regulated. the voltage regulator light is only illuminated for a second after "HV ON" is pressed
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Steven Sesselmann
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Re: Spellman XLF mystery malfunction

Post by Steven Sesselmann »

Silly question, but do you have a load on it?

Steven
http://www.gammaspectacular.com - Gamma Spectrometry Systems
https://www.researchgate.net/profile/Steven_Sesselmann - Various papers and patents on RG
George Ressinger
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Re: Spellman XLF mystery malfunction

Post by George Ressinger »

yeah, I have it connected by a cable/plug i made to the grid in my chamber. though it isn't evacuated.
John Futter
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Re: Spellman XLF mystery malfunction

Post by John Futter »

So the chamber is lighting up
1.7kV sounds about right
disconnect the cable from yje PSU to your chamber and see what voltage control you have
Dan Knapp
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Re: Spellman XLF mystery malfunction

Post by Dan Knapp »

If the chamber is not evacuated, then you have no load on the supply.
George Ressinger
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Re: Spellman XLF mystery malfunction

Post by George Ressinger »

problem solved, just had to connect some more pins on the jb connector on the back so the supply would think it was properly connected.

all knobs, displays, and buttons are working properly, which means I"ll be firing immediately after I get my vacuum properly sorted.

many thanks,
George
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Re: Spellman XLF mystery malfunction

Post by John Futter »

Dan
Of course there will be load on the psu with the chamber filled with air, The air ionises and therefore conducts, I use this @ work to save time tracing ionsource shorts --saves waiting for vacuum
Dan Knapp
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Re: Spellman XLF mystery malfunction

Post by Dan Knapp »

12.7 ma at 1.7 kV through air at atmospheric pressure?
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Re: Spellman XLF mystery malfunction

Post by John Futter »

Dan Actual current and voltage depend on many parameters
But our usual penning ion sources and anode layer sources typically run @ around 2kV 5mA anode to cathode under Vacuum.
On the bench in air raising voltage slowly breakdown @ 3kV and voltage falls to as per current limit to 1.2- 1.6kV 10-20mA.
It pays not to muck around for too long as the ozone production doesn't do the metal and insulating surfaces much good
Dan Knapp
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Re: Spellman XLF mystery malfunction

Post by Dan Knapp »

John
Unless the air in New Zealand is significantly different than air in South Carolina, we seem to be having a miscommunication. You seem to be saying that an electrode at atmospheric pressure with -3 kV on it will show a discharge current of milliamps. I regularly operate apparatus with 15 kV on the atmosphere side of feedthroughs and see at most a few microamps leakage, most of which I believe is surface leakage rather than corona. Just to be sure I wasn’t missing something, I just put -3 kV on an exposed point (BNC center conductor) with a current meter that reads down to 1 microamp, and I see no discharge current in air. I don’t believe anyone is going to see much current drain at all with a power supply connected to an unevacuated spherical fusor.
With regard to your comment about testing ion sources at atmospheric pressure to check for shorts, I don’t see the relevance to the discussion at hand. In my prior life, I spent forty years working on ion sources and always checked for shorts at atmospheric pressure before evacuating the system. Are you talking about putting high voltage on the source at atmospheric pressure? (how high?) If so, and you say that you get milliamp currents from discharge in air at a few kV, how could you see a resistive short in the presence of milliamps of air breakdown current?
Please tell me what I’m missing here.

P.S. My lab is at 23 degrees, 58% relative humidity. Its very humid here, but I didn't think atmospheric moisture was a very good insulator.
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Richard Hull
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Re: Spellman XLF mystery malfunction

Post by Richard Hull »

Dan is spot on! After years in the Tesla coil business and working in real atmophere work with superb instrumentation, especially electrometers, micro amps are what one would expect in free air bleeds at high voltage in the 1-10kv range. Once highly visible corona occurs it can go up to a hundred micro amps, maybe.

A working load current of an electrostatic motor with a 100 gram rotor, spinning at 2300 rpm, at 20kv applied with noisy coronal hiss is on the order of 400 microamps here. I know, I have one and demo it regularly.

Milliamps?! If you measured milliamps, something is grossly wrong with your instrumentation or the supply.

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
John Futter
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Re: Spellman XLF mystery malfunction

Post by John Futter »

Dan
please read what I wrote carefully all is there
and to find a resistive fault is easy as current flows before breakover.
However the worst kind of faults are the ones that are open circuit at low voltage and suddenly short before operating potential is reached
And our RH and temp range is very similar
Dan Knapp
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Re: Spellman XLF mystery malfunction

Post by Dan Knapp »

John
I did reread your posts and had overlooked that you were talking about Penning and anode layer sources. That is a very different kettle of fish than a fusor. Both of these sources have a magnetic field that causes the electrons to take helical paths. You can of course get discharge at higher pressures and lower voltages in a magnetic field (increases path length of electrons and probability of ionization), but this has no relevance at all to a fusor.
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