Bertran Model 205A-03R High Voltage Power Supply

[btufekci]

Hello,

I have an old school Bertran Model 205A-03R High Voltage Power Supply. I had the voltage at like -400V and switched the polarity without dropping the voltage to 0. Now it's giving me no voltage. Is it fried? I opened it up and the components look fine, and I don't see anything physically wrong with it.

Nevertheless I'm getting no voltage or current readings. Does anyone have any experience with this? Could someone at least send me to a forum where old school high voltage power supplies are repaired?

Here's what it looks like: https://www.surplussales.com/PowerSuppl ... 3rd_L.html


Thank you!

[JoeBallantyne]

Some old school supplies require you to turn the voltage all the way down, before you can engage the high voltage switch.

Then after the high voltage switch engages (only while the variac is all the way down), you can then turn up the voltage.

Try turning the voltage all the way down, then switch on any HV enable, then raise the voltage.

In general it is a TERRIBLE idea to try to switch from positive to negative while the HV is on. You very well may have killed the supply, regardless of whether or not anything is obviously destroyed.

It is always a good idea to try to find the manual online for any old supply, and READ IT before messing around with the supply. It is amazing what one can learn by simply RTFM.

Joe.

[JoeBallantyne]

This popped from a quick google search. I suggest reading it.

Bertan-205A-10P-Specifications-AC56C.pdf

(1.46 MiB) Downloaded 37 times

Joe.

[JoeBallantyne]

From the above linked manual. (I couldn't copy the text, so I snipped it.)

I'm afraid Mccoy's diagnosis might well be "It's dead, Jim."

Its ALWAYS good to read the manual FIRST.

Joe.

[btufekci]

Yeah I most likely killed it. I admit I made a foolish mistake. Thanks for the responses. I would like to know why though and how this works? Like, what is the idea/theory behind switching polarities in high voltage power supplies? In fact, I've accidentally shut down a power supply while the voltage was at like 2kV and nothing happened to it. What happened when I tried switching the polarity from -400V to +400V without dialing down to 0V.

Thank you all!

[JoeBallantyne]

From the manual, you actually are supposed to have the supply completely disconnected from power, and fully discharged before doing the switch, not just dialed down to zero volts.

Clearly the internal design was not meant to have the polarity switched while under power. It killed it.

Could have been for many reasons. One thing that comes immediately to mind, is that if you had the output at -400V and switched to the opposite polarity, the supply would very likely get overloaded, trying to pull its output capacitors from -400V to +400V, and burned something out due to excessive current draw.

There are of course many other possibilities. Clearly per the manual, and your experience, switching polarity with the supply energized is a fatal (to the supply) mistake.

Joe.