Need Help Diagnosing Fault in EVG EPS200 UV Lamp Driver (Power Board Issue)

https://www.radwell.com/Buy/HONLE%20GROUP/HONLE%20GROUP/EVG-EPS200?srsltid=AfmBOoreK_fBtm6EQTLHoOW3MSSOb14eku8UXp-PooNZ_oPksoDjT1Ob

This unit has been discontinued, I would obtain another unit while you still can, and repair the one you have now for a backup...

https://industrialrepairstore.com/product/honle-uv-america-inc-evg-eps200/

It sounds like the diagnostic is pointing to an earth connection on the lamp supply leads, so it would be good to figure out just how that earth connection is monitored, such as a low current connection at the output leads going back to the control board.

I assume the lamp hasn’t illuminated for you, but if you can measure the voltage to earth in the short time the system powers up on the lamp leads, you might get some information. Or measure with an ohmmeter with the lamp out of the circuit.

It seems you’ve done a thorough job checking your components, what happens if you disconnect the lamp, for example.

It could be helpful to use an oscilloscope measuring lamp supply voltage to earth during power up, the power board will gate on a low voltage for a short time looking for current flow or low voltage for maybe a half cycle at power up for both leads.

Here is what I found when I did search for a circuit schematic diagram for the EPS200:

Not very clear, but it may help if you enlarge it.

IGBTs/MOSFETs may check good with a meter, but fail under load. If all else fails, replace them.

There are links on this page to professional repair services with warranties:

https://youtu.be/7_glWtnjW_8

https://duckduckgo.com/?=++circuit+board+schematic+for+EVG+EPS200&atb=v461-1&ia=web

It would be embarrassing to send out the module to be repaired only to find out the problem was in an external component...

Be sure to check all interconnecting wires and connectors.. Any discolorations may indicate poor, loose or intermittent electrical connections.. If I were you, I would jiggle /wiggle, bend and pull or apply some tensions on some of the wires as you search around for what is causing the problem...You may have a break in one of the wires?

An octopus and Lissajous patterns always helped me when no advice or docs were available.

I see a couple of polarised capacitors in the circuit schematic HTRN found: if any of those are aluminium electrolytics I would replace them. Far and away the most common cause of failure in power supplies.

As it takes a few seconds for the fault to appear, I would look at as a thermal issue. Try gently heating the board and re-check.