How To Repair A Plasma Ball

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Firefox

Thu Jun 26 2008, 04:30am

Registered Member #1389 Joined: Thu Mar xiii 2008, 12:50am
Location: Pittsburgh, PA
Posts: 346

I was over at a friend's firm today when I spotted an old plasma globe in the corner, all dusty and neglected. Of class, I couldn't let that wonderful piece of HV hardware go unnoticed, and asked him why he didn't have information technology plugged in, and he said it was broken. And then I plugged it in, and certain enough, I got one or two thick, fairly vivid solid streamers to the glass. Knowing what it should expect similar, I knew this wasn't right, and I heard some whining from the step-up board.

Now that I take the thing home and taken apart, I found its a unproblematic TL494 driver into a mini AC flyback transformer. The vacuum in the globe seems fine, every bit the driver board got the same operation with a burned out light seedling. I found one of the transistors gives a resistance reading of shut to zero (or even negative) and then slowly works its way above my multimeter'southward range, well-nigh 2Mohms. Is this an indication of its failure? Also, there seems to exist a identify for a large polarized capacitor next to this transistor, could it be possible that this cap was left out accidentally?
All of the caps give a infinity reading on the meter, and the resistors give nominal resistances. I would like to repair this thing, as it seems nothing is terribly incorrect with it. It also seems like it would exist a fun thing to drive a CW multiplier off of.

termination
Registered Member #1559 Joined: Mon Jun 23 2008, 10:17am Location: Posts: 10	Look up the datasheet for the transistor (simply google the number that'southward written on it) and see if information technology says annihilation virtually internal resistance or other specs that might intrest you.
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Dr. Dark Current
Registered Member #152 Joined: Sun Feb 12 2006, 03:36pm Location: Czech Rep. Posts: 3384	I would say that the gas within the globe has leaked. If the HV is working and so most probably information technology is working as it should. Otherwise yous would come across smoke, blown fuse etc.
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KresoLiubov

Registered Member #1153 Joined: Monday Dec 03 2007, 07:27pm
Location: Croatia
Posts: 213

I can help you little:

I collect plasma globes and all variations of them. There is always place for electrolytic capacitor on input but its never populated and i populate it myself and it makes performance better.

Are you lot sure there is a TL494? In every unit of measurement i disassemble always there was HEF40XX within, except i used feedback winding.

Here is what brakes on 99 % of this plasma globes:

The nipple where was air pulled out and gases pushed in is on bottom side. Normally by assembly the nipple comes exactly side by side to FET oestrus sink. Trough time there is a modest discharge from nipple to estrus sink and glass slowly "fissure" until air escapes inside. All plasma globes i take i put the globe few cm upwards (its in rubber stand) to escape from this problem.

I don't remember you circuit is expressionless. I will be on your plasma globe and that it allow air in. Second thing to endeavour is to input picayune bigger voltage, come across if it will piece of work fine. Those Chinese transformers that come with it overheat and die soon.

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Firefox
Registered Member #1389 Joined: Thu Mar xiii 2008, 12:50am Location: Pittsburgh, PA Posts: 346	Yes, its a Texas Instruments TL494CN to exist exact. One transistor is a TIP122 (heatsinked) and the other is an NEC D882. What kind of cap do you unremarkably put in Kreso? The other caps on the board are x or 1uF 50V along with a 3.3nF film foil and a 10nF ceramic. I tried hooking the output of the board to a burned out light bulb, and functioning was about the same, given I had my fingers shut to the glass. Without a nearby ground, at that place weren't fifty-fifty streamers, though I exercise not know if this is a fair comparison or not. In any case, if the earth is broken, in that location are all kinds of other things to practise with this lath.
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KresoLiubov

Registered Member #1153 Joined: Mon December 03 2007, 07:27pm
Location: Republic of croatia
Posts: 213

Firefox wrote ...

Yes, its a Texas Instruments TL494CN to be exact. One transistor is a TIP122 (heatsinked) and the other is an NEC D882.
What kind of cap do you usually put in Kreso? The other caps on the board are 10 or 1uF 50V along with a 3.3nF film foil and a 10nF ceramic.

I tried hooking the output of the board to a burned out light bulb, and functioning was almost the aforementioned, given I had my fingers close to the glass. Without a nearby ground, there weren't even streamers, though I do non know if this is a fair comparison or not. In whatsoever case, if the globe is broken, there are all kinds of other things to do with this lath.

Merely any used non need electrolytic i take. 16-25 V 1000-4700 uF.

Very interesting that its a TL494 i never seen it.

If you connect a light bulb and there isn't o sparks inside (until y'all put a finger there) then there is still a hope your world is fine. 1 funny thing that could happen is the frequency determing cap dying and its working on some foreign frequency which is not good for plasma world?

Or your flyback transformer is busted. If you had one more plasma globe you lot could know fault in ii minutes. BTW what is size of plasma globe? Dont tell me its tat 25 " i forever desire . Can you browse or post photos of both sides of board, i would exist glad to see how its made

Firefox
Registered Member #1389 Joined: Thu Mar 13 2008, 12:50am Location: Pittsburgh, PA Posts: 346	Haha, the earth is a half dozen", not anywhere close to being a 25". In any case, I will endeavour putting 1 of my squeamish big electrolytics on it correct now. I may take some caps to replace the originals as well. Strange that the mini transformer could be busted, as I can yet draw faint 3 mm arcs to an ungrounded screwdriver on the end of a plastic stick. What frequency are these things supposed to operate at? Similar I said in my original postal service, one of the transistors whines when ability is supplied, and I don't retrieve the manufacturer would take intentionally left information technology in the audible range.
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Hon1nbo
Registered Member #902 Joined: Sun Jul fifteen 2007, 08:17pm Location: Due north Texas Posts: 1040	Firefox wrote ... Haha, the globe is a 6", not anywhere close to being a 25". In whatsoever instance, I will effort putting i of my nice big electrolytics on it correct at present. I may have some caps to supplant the originals equally well. Foreign that the mini transformer could be busted, equally I can still describe faint iii mm arcs to an ungrounded screwdriver on the end of a plastic stick. What frequency are these things supposed to operate at? Like I said in my original post, i of the transistors whines when power is supplied, and I don't call up the manufacturer would have intentionally left it in the audible range. they by and large wont be in the aural range (who that is not an HV enthusiast wants that dissonance for a petty gadget?), I take a spare board around hither and it nonetheless works as far as I know... I will see if I tin make up one's mind the frequency, but first I have to borrow some things from a teacher at my school and I can let you lot know, but there is a good chance that someone here knows...
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Firefox
Registered Member #1389 Joined: Thu Mar 13 2008, 12:50am Location: Pittsburgh, PA Posts: 346	Update: Schematic. T1 is the NEC D882 and T2 is a TIP122. The chip is a TI TL494CN.
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KresoLiubov
Registered Member #1153 Joined: Mon Dec 03 2007, 07:27pm Location: Croatia Posts: 213	All my plasma globes, even iv " ones give a 1 cm spark. Really foreign it sound similar your flyback shorted somewhere. At that place is no cap on pin 5 ?
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