NIM Power Supply Fix

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Aidan_Roy
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NIM Power Supply Fix

Post by Aidan_Roy »

Hello,

I just got a Nuclear Chicago 3 Kv power supply for my NIM bin and it was cheap. It looked to be in good shape cosmetically on the outside but sadly is not functional as hoped. The only obvious thing I can see upon opening it up is one wire that is disconnected from where it belongs. That’s where I need the help. Assuming all of the bits and pieces are all still working, re-soldering this one wire should allow the thing to work but since I don’t know anything about the circuitry and can’t get a wiring diagram for the product, I don’t know where it goes. The indicator light still comes on if I turn the high voltage on but there is no output. Pictures attached below. Thanks if anyone can help but if not I’ll just return it and find a working one for sale.

Aidan
Attachments
Top
Top
Right side panel
Right side panel
Bottom
Bottom
Left side panel zoomed in on affected area
Left side panel zoomed in on affected area
Left side panel
Left side panel
Last edited by Aidan_Roy on Wed Aug 26, 2020 11:48 am, edited 1 time in total.
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Richard Hull
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Re: NIM Power Supply Fix

Post by Richard Hull »

I see the bare wire, it is on the voltage control pot. I probably goes to some spot on on of the control boards. Don't know where. I would have to be in person to make a good guess. sorry...

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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Dennis P Brown
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Re: NIM Power Supply Fix

Post by Dennis P Brown »

Unless someone cut that wire free and it is now far shorter then it was, not exactly many places that wire can reach. If you believe it is original (not been cut short) it is fairly obvious what it was connected to - the item in the pic appears to have a piece of wire remaining that might have been that wires connection point. Unless you can find a circuit diagram, at some point you have little choice but to try the only location it can reach (you got the unit cheap and it is currently a boat anchor so not exactly a huge loss if you are wrong on that guess. At least it doesn't use ultra touchy chips.) Also, make sure that pot is turned all the way down before applying power if you try that route.

Do realize, even if you connect it to the correct location, that doesn't mean the unit will work - there might be other issues. Buying non-working electronics is always a risky business. If in worse case it does not work, that units has some very nice high voltage (HV) diodes, and caps - wouldn't be difficult to take those components, test the HV x-former, and then use those parts to make your own HV supply. That diode bridge could be used as is.

Aside: I saw a fuse in one pic. Do check any/all fuses - could be an issue, too. Finally, if you do try it, be careful of those HV caps (they might charge up even if you get no output from the unit and their bleed resistor's might not be functioning.)
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Richard Hull
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Re: NIM Power Supply Fix

Post by Richard Hull »

The more I look at this, I think the supply might be modified for another use. In pix 3,4,5, I see what looks like non-manufacturer wire. The fine red wiring looks like 28-30 gauge wire wrap wire.
Check all solder points for this wire. If bright and shiny or if the joint looks either bunged up, rosin covered or vastly different in shine over other solder joints then suspect modification by some past user or a terrible attempt to re-purpose or even repair the thing. I could look and tell at an instant. my eyes are not there, though.

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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Aidan_Roy
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Re: NIM Power Supply Fix

Post by Aidan_Roy »

Richard, one of the fine red wires looks like it could not belong. The other looks like it does belong but, it could be that it was just buried under the solder that was already there. I think you are right as far as someone trying to repurpose it because the voltage control knobs actually lower the tiny amount of energy coming out when it’s turned on. Turning up either one will lower the output and same goes for the vernier pot. More energy comes out of the delta E control than does from the high voltage output.
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Richard Hull
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Re: NIM Power Supply Fix

Post by Richard Hull »

The beauty of NIM is that a good electronics man can specialize the modules as needed to a specific purpose desired. I have seen this a number of times. Of course, as surplus, the units are not what they were in the beginning, but the original owner who paid the freight at full list price and modified it, got his use out of it, once modified.

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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Rich Feldman
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Re: NIM Power Supply Fix

Post by Rich Feldman »

Aidan, can we see pictures of the front and back panels, from outside?
Maybe some reader here will recognize the model; might even have a datasheet.
[edit] nameplate is visible in your side panel picture. [\edit]

FWIW, I could provide schematic diagram for the Ortec 459 bias supply module reported in a thread last year.
Runs on +/- 24 V. Discrete transistor multivibrator, step-up transformer, voltage multiplier (in module that's reversible to get + or - HV).
The softness of the output (equivalent impedance 2 megohms?) comes from intentionally small C values in the multiplier.
viewtopic.php?f=13&t=12649&p=82952
All models are wrong; some models are useful. -- George Box
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Aidan_Roy
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Re: NIM Power Supply Fix

Post by Aidan_Roy »

Rich,

Not sure if it will help even if a schematic is found but here they are.
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7B906C08-4837-4AFF-82F4-A11948545145.jpeg
CD3D1E1C-FB0C-4BBE-96D7-CCDD54C5EB35.jpeg
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Richard Hull
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Re: NIM Power Supply Fix

Post by Richard Hull »

Gee whiz! I consider myself a bit of an expert on Nuclear Chicago instrumentation. I collect and use there old stuff extensively. This is the first time I have ever heard of or seen any NIM stuff made by them, but it seems reasonable, in retrospect.

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: NIM Power Supply Fix

Post by John Futter »

Aiden
please post pics of each circuit board take one out at the time so you do not mix them up
they should be keyed so this does not happen but???
your first pic shows three wires that were not part of the original
Red blue grey so someone has been playing
note all the other wires are stripe colored to identify
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Aidan_Roy
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Re: NIM Power Supply Fix

Post by Aidan_Roy »

John,

I edited the original post labeling the pictures. I labeled them based off of the orientation that the module would be sitting in in the bin.
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Rich Feldman
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Re: NIM Power Supply Fix

Post by Rich Feldman »

Could anyone use a free spool, or two, of the narrow waxed ribbon used to lace up wire harnesses?
Then you can make your restoration, or hack, hard to distinguish from the original. :-)
All models are wrong; some models are useful. -- George Box
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Re: NIM Power Supply Fix

Post by John Futter »

Aidan
What i meant
please pull each circuit board out of its edge connector and photograph it please
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Aidan_Roy
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Re: NIM Power Supply Fix

Post by Aidan_Roy »

John,

Here are the boards.
Attachments
HV Regulator Board back
HV Regulator Board back
HV Regulator Board front
HV Regulator Board front
LV Supply Board back
LV Supply Board back
LV Supply Board front
LV Supply Board front
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Re: NIM Power Supply Fix

Post by John Futter »

Aidan
there are not many components you can check all resistors with a DMM look for carbon ones that have gone high in value
cap lift an end and measdure capacitance
transistors use the DMM diode function to check BE BC EC CE

you still need to try and find where thr three wires from the pot should go --use a magnifying glass to check possible solder joints /connections
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Aidan_Roy
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Re: NIM Power Supply Fix

Post by Aidan_Roy »

John,

Honestly, I’m not sure it’s worth it to try and fix. I can either return it and replace it with a known working one or I can harvest all of the still good components for later use and replace the PSU anyways. The more I look at it, there just doesn’t seem to be a high chance of this thing being repaired to its original state.
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Richard Hull
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Re: NIM Power Supply Fix

Post by Richard Hull »

Aidan, I assume you are in the U.S.? if correct, I might buy offer to buy it it if low enough in price. Remember I collect Nuclear Chicago stuff. I might try and repair it or just add it to my collection of N.C. broken.

With no metering, it is not a great piece to own for NIM work. I noticed they changed their really cool logo on the label. Boo, hiss...

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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Richard Hull
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Re: NIM Power Supply Fix

Post by Richard Hull »

A follow up. I did buy the supply non-working from Aidan and fixed it this morning between midnight and 5 AM. It turns out someone had been soldering in the supply. Probably they were trying to troubleshoot via disabling various sections. I cleaned up their solder joints. I ultimatedly found one bad transistor on the multi-transistor control board and two 9.5 volt reference diodes. Tweeked the pot on the board to fine tune the 500 volt switch output to true 500 volts. (it was 480 volts before the tweek.)

Now it will joined other Nuclear Chicago items I have, but as a now working item.

I note that based on the manufacture's tagging Nuclear Chicago had been sold to Searle Ind. and was now claimed as a division of Searle. Nuclear Chicago lost it identity some time in the 70's.

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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Aidan_Roy
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Re: NIM Power Supply Fix

Post by Aidan_Roy »

Richard,

I am glad you were able to repair the unit. I saw a few solder joints as well and tried to see if the broken wire was supposed to go to one. Since none were correct, for reasons you have now made known, I left some messy. Not more than 2 though. As far as the bad transistor, I would not have had enough justification in finding a flaw like that so, I’m glad that all worked out well. Thanks.

Aidan
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