How to switch polarity of a Laser PS Kit

[Larry Upjohn]

I have a laser power supply kit complete with stepup xformer, xformer diode bridge, and multistage multiplier resulting in a "positive" output and ground for final laser supply. Where do I start reversing diodes to convert it to a "negative" output and ground for fusor use. I understand the process of diode reversal but I am not sure if I need to reverse all diodes in the kit including the transformer diode bridge or just the diodes in the multiplier. Thanks for your help. I have checked several textbooks, Online HV Wikis and here and the process is well described but it is not clear to me how much of the diodes in the whole PS should be reversed. Stupid question for the day (or rather senior moment question). Larry Upjohn.

[Carl Willis]

Hi Larry,

I'm not sure how it could have both a "diode bridge" and a "multistage multiplier." Are you able to provide a coarse schematic so I might be able to better understand the situation?

If it's got a bridge or a multiplier, all you have to do to reverse output polarity is reverse each individual diode. Take it out, put it back in facing the other direction. Caveat, though...if the power supply circuit uses feedback from the output to either operate metering or control circuits, reversing the polarity will probably cause improper operation of those circuits and they will have to be reconfigured.

-Carl

[Larry Upjohn]

Carl;
Thanks for the quick reply! I was attempting the note from memory and I may have not have this correctly described. I have continued to search and have answered the CW side of the question. I will attempt to scan the schematic and attach it here for future reference. I believe there is some sort of feed back that is adjusted for specific laser tubes. More later, Larry Upjohn.

[DaveC]

Larry -

Without a schematic this is only a guess, but early Spectra-Physics Lasers used a multiplier to get enough kV to light up the tube (strike the arc, so to speak). That multiplier was quite small capacity, so once the laser lit off, its output would collapse to the voltage of the main HV supply.


Not sure that's applicable to your system... FWIW.

Dave Cooper

[pfostini]

What is the name on the power supply. Its a spectra Physics Model ?