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John Noell
07-16-2016, 10:37 PM
Prelude: I thought I would finally replace the cheap PSU that came with my Shenhui and put in a RECI PSU. I plan to replace my tube soon as it has lost just enough power that I cannot cut the wooden keytags out that I often make. I thought I should first do the PSU, then when all is okay do the tube. However, not all IS okay.

The RECI PSU alarm (yes, it has an alarm and a nice LCD display with temp, humidity, incoming voltage, and output specs) keeps going off and saying there is a short. Thinking that the old high voltage wire might be the problem, I replaced it with RECI's new (slightly thicker) wire. The wire from the PSU is about 18" long, goes through an insulated connector (like many if not most Chinese machines have), and then goes to the tube. There is no sign of arcing. After checking the connector inside the insulator (no problems visible) I have suspended the insulated connector in the air so nothing is near it. I removed the metal box covering the end of the tube and can see where the wire connects to the tube. There is no sign of arcing. Sometimes, I can run the laser for a while without the alarm going off, but not usually for very long. The laser usually continues to fire even as the alarm beeps away - but at least once the laser also stopped firing until I turned off the power to the tube and (after waiting a minute of two) and turned it back on. When I put the Shenhui PSU back in, everything works like it should. I would like to use the (supposedly) higher quality RECI PSU but I cannot figure out why it keeps saying it is unhappy. Any suggestions would be welcome!

Dave Sheldrake
07-17-2016, 6:07 AM
Run 3mm bore 7mm OD silicone tube from the block connector yo the tube over the wire John,likely current leaks from the wire as at best they aren't the best insulated.
Check coolant as well, the RECI supply will detect current leakage into any conductive coolant as well.

John Noell
07-17-2016, 9:58 PM
Thanks Dave. The coolant is just plain water (no antifreeze needed in Fiji!) so not much conductivity there. I'll have to order the silicone tubing from overseas as there isn't like to be a source in Fiji (and certainly not on my island). I guess I will go back to the Shen PSU until I can source the tubing.

Just ordered it from UK. :)

Dave Sheldrake
07-18-2016, 6:29 AM
Distilled water? most types of tap water are conductive (contamination) from memory the RECI psu also pre-ionises so has a trickle current running (usually 4mA) and that can cause issues as well :)