Spellman -40kV PTV power supply

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Re: Spellman -40kV PTV power supply

Post by Richard Hull »

I am unsure of your HV connector. I have several Spellman supplies that I picked up at hamfests. The ones I have have what looks like a PL259 uhf type threaded barrel with no guts in it sticking out of the back. I have cobbled up my own cable with large diameter, heavy, yellow, 50kv, silicone auto ignition wire, (copper core). I solder a naked banana male end, (barrel removed0, to the silcone cable. I next get a piece of plexiglass or lexan tube about 12-inches long and thread the silcone wire and banana plug through it. Note: the tube must, obviously, slide smoothly into the PL259 opening.

Epoxy the banana plug such that only the point of the plug extends from the end of the plexiglass. No need for a shielded cable here as long as you are mindful not to touch or move the silicone wire while the supply is on. Note: the plexiglass tube must extend about 3" outside of the back of the unit for insulation purposes.

Hope this helps and is the type plug you have on your device.

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 -40kV PTV power supply

Post by Cliff S »

Regarding Andrew’s Q’s:
One schematic is dedicated to the X2094, the single PWB, open air HV type construction. (See title block). The other is the Control PWB for the generic PTV series, the potted HV section with the 2-PWB construction. The inverter sections (half-bridge FET’s) are basically the same. The HV in the potted section is a half-wave CW, with feedback R’s and stuff like that.

350W is OK for continuous operation, with some air cooling. 600W is pushing it. Maybe OK for some low duty, maybe 1 minute ON, 10 minutes OFF. But don’t yell at me if you pop those diodes.

Not sure why you would be getting OVP faults. But it’s possible. Really hard to say about any post filter. Probably not a concern on stability. If in doubt, just put a large R in series. As large as you can allow. Make sure it can handle the 40kV impulse, and the power.

On the HV connector: That model has an LGH 4I style. Google it. Good luck. It may be tough to find. Let me know if you hit a dead end.

On Rich’s comments on the HV connector: I think maybe this is a general comment, and yes, Rich, you have it deciphered. See attached as an example of a typical cable construction. This however is NOT the cable that would mate to Andrews unit, it’s just an example of how one type may look. Andrew’s connector will not support 40kV reliably unmated, and without the proper mate. LGH styles rely on a compression fit, forcing our air. Generally called “cone” type connectors because of the cone taper shape.

Best Regards,
Cliff Scapellati
Executive Vice President of Engineering
Spellman High Voltage Electronics
631-630-3110
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Does anyone have a table with the jumper functions?

The LGH-4i connector is hard to find, no-one stocks it as a standard component, they are all made to order and cost several hundred per unit. It would be easy to male a matching connector if I could find the metal nut for the connector, it is a 1-14 thread. Does anyone know a good source for a cap / compression nut with this thread?

Andrew
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

I decided to make my own connectors. The nuts are made by turning down a 1-14 brass jam nut, and silver soldering (w/ kester 2222 flux) a washer onto the top. The washer is partially recessed into the nut face for proper centering(nut was turned down on a 1-14 precision arbor to center the threads on the lathe axis) and the soldered area was then filed down so there is a seamless transition between the nut and the washer. The threads on the nut were smoothed with purple scotchbrite so they don't damage the plastic LGHI thread on the connector.

The brass hex nuts are:
http://www.ebay.com/itm/360415477101?ss ... 1497.l2649

The washers are:
McMaster P/N 92916A420

The HV plug will probably be made out of PEEK, and will be held into the connector with the nut.

Andrew
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Re: Spellman -40kV PTV power supply

Post by mircado »

Cliff S wrote:See attached.
The PTV series has many generations, and has many custom models. No claims made on how accurate attached doc is to your models.
Sorry, can't send some of the high kV schematics. Our policy is not to share that knowledge in such detail.

As always, any servicing of these units should only be made by qualified service personnel. Be careful.

Best Regards,
Cliff Scapellati
Executive Vice President of Engineering
Spellman High Voltage Electronics
631-630-3110
Dear Cliff Scapellati ,
thank you for your services
if you please i need the schematic for spell man PTV5N350
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Re: Spellman -40kV PTV power supply

Post by mircado »

i have T3 burnt in PTV5N350
what can causes this and what can i do and what is alternative
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Re: Spellman -40kV PTV power supply

Post by Richard Hull »

An image of T3 would be nice. It could be a death spiral for the rig or an easy fix. No pix, no suggestions.

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 -40kV PTV power supply

Post by Dennis P Brown »

Interesting series of posts; I too have one of these 40 kV, 5 ma units (with the proper HV cable/connector rated to 50 kV.) So, just adding forced air cooling along with a low input fusor resistance allows a higher current draw to be safely handle by the unit? Of course, a proper ballast resistor must be included in line with the fusor.
So, would 10 -12 ma then be a workable safe limit?

Also, Mr. Couter, concerning this part of your post
It might take nothing more than using a larger cap across the supply output before the ballast impedance - but you'd need either a large inductance or something that would limit the micro arc current to lower levels and let it "go out", which a 100k ballast resistor alone doesn't manage to do.
(In fact, going to that from 50k only dropped the voltage under load - no other change was noted)
I have a 50 kV 0.2 uF cap. Exactly what does that buy me if I place it on the output side of my Spellman unit for continuous operation (besides instant death if I make a mistake ... )? I thought that adding a cap in that part of the circuit only helps with output ripple and nothing else (assuming this isn't a reference to a pulsed system; then the usefulness of the cap for increased current is obvious.)
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Finally got around to modifying the spellman supply, I am now well versed in how the spellman feedback control circuitry works.

Modification of power supply successful, system now operating at 9mA output. The modification involved changing the voltage input on pin 10 of U7 (LF444ACN) from 5V to 9V. My version of the supply has a non-standard current feedback calibration of 1V/mA rather then 10v=100%(5mA) so the gain of the MAFBK op-amps did not have to change. This brings the current limit to 9mA instead of 5mA, the previous limit for the 200W version.

The transformer secondary does start to get hot as viewed on a thermal imager, next modification is to add an internal blower to blow air over the winding.

The OVP problem was caused by the power supply being designed to take a 0-4v input for 0-40kV output, rather then the 0-10v for 0-100%(40kV). When connected to the 10V reference the input potentiometer was trying to tell the supply to go over 40kV and tripping the OVP circuit.
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Also, the HV cable that I built for the LGH-4i connector. An o-ring(not shown) fits on the barrel and is compressed against the fitting when tightened
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Re: Spellman -40kV PTV power supply

Post by Richard Hull »

Very, very nice work Andrew. This shows "where there is a will, there is a way"! Onward and upward.

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
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Annotated schematic with modifications:
spellman-annotated-schematic.pdf
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

As advised by Cliff, I have added a blower to keep the HV transformer secondary cool. It is a 12v blower and is fairly high performance generating significant airflow over the winding. The power supply is designed for a 24v fan so a DC-DC converter is used to convert the voltage to 12v.

12v DC blower
SAM_4446a.jpg
Standoff added to power supply
SAM_4447a.jpg
12v DC blower mounted on standoff and aimed over transformer winding, DC buck converter converts 30V from supply to 12V for the fan
SAM_4448a.jpg
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

Drawing power from the 24V port was found to cause a voltage spike of shutdown(even though this is where fan power was supposed to come from). Instead an AC-DC power brick was connected to the internal corecom inlet filter to supply power to the fan, solving the HV spike problem
SAM_4506a.jpg
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Re: Spellman -40kV PTV power supply

Post by Garrett Young »

Another question for Cliff ...

Is there any headroom on the voltage multiplier section? Can the PTV30N be run at 31 or 32 output kV with feedback modification?
- Garrett
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Re: Spellman -40kV PTV power supply

Post by mircado »

Hello
I have a spellman high voltage power supply have a burnt transformer T3.
What is the solution and what id the reason
Best Regards
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Re: Spellman -40kV PTV power supply

Post by Dennis P Brown »

First, great post and work, Andrew!

Poster mircado - first, you need to fix your name, we use full names in all sections (yes, nick names are used by people in day-to-day activities but policy here we use full names). Second, using someone else's post to ask your own question is not the proper method (I understand the reason.) Rather, start your own post or send a PM to the poster.

Thanks and good luck with your efforts.
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Re: Spellman -40kV PTV power supply

Post by Andrew Seltzman »

My best guess is to try to find a similar surplus secondary and try to replace the burnt one, it would be pretty difficult to wind your own (though not impossible).
Also you posted about this in this thread in 2015, is this the same supply?
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Re: Spellman -40kV PTV power supply

Post by mircado »

Thank you for your reply.
Yes it is the same, i change the complete unit before.
Now it is very difficult to change it again so i am searching for another solution
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