[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [kinda-ot] Plasma ball driver HVPS



Original poster: "Dr. Resonance" <resonance@xxxxxxxxxx>



We have replacement boards for flybacks. We used a MOSFET that switches the 120 vac directly to produce the HV to drive the globe.

Contact me off-list if you want to order a new board.

Dr. Resonance



I've been given a HV powersupply for a plasma ball with the request to repair it. I've been googleing for the last few hours and I can't find anything similar to this design.
This list seemed like the best place to ask for some guidence.

I'm an EE but I'm mostly a uP level digital man. So this is a tad bit out of the bulk of my expertise. I have played a bit with HV in the past though and I'm not a total stranger to analog but I'm not having any luck getting my head wrapped around this circuit.

The PS uses a flyback xformer with a custom wound primary just like you see in all the 2n3055 designs all over the net. The key difference is that it dosen't use low voltage on the primary winding.

The whole thing runs off of filtered, half-rectified 120VAC. The power transistors mounted on to a heatsing are a MJ8501 and a D40E5. I found data on the MJ8501 but not on the D40E5 other than its a high frequency NPN. I found some crosses listed for the D40E5 but the pinouts on them don't seem to make sense with what I see in the wiring.

I've tried to draw out most of the circut but when I get to how the trasistors are wired up it's confusing. The flyback has 3 other parts of the coils hooked up to the trasistors. Without the wireing info of the flyback and the the pinout of the D40E5 I don't have much of a clue how its hooked up. Its obviously got to be some manner of osciliator for it to pump the flyback but its certainly non-obvious to this digital boy.

This apparently was some sort of kit that was purchased aound 10 years ago.

Has anyone have any idea what setup I may have or perhaps a link to any flyback driver circuits that drive the primary with 120VDC?

I'll be happy to go into much greater detail on what I have drawn on the the schematic if anyone is interested in helping me figure it out.

TIA,

--
Richard.