Failing SPS705 power supply (68vdc Leadshine)

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Thanks for your reply John and for the tips on the cap charge!

Indeed it might be a faulty controller / stepper, I simply jumped to the conclusion it's the PSU as the voltage was fluctuating so much, first only moving between 40-60VDC, then slowly drifting more and more towards lower voltages, now only moving between 0VDC and 20ish VDC. Oddly enough the stepper still works, not straight away after switching the power on, but if you leave it for a few minutes the voltage must creep above 20VDC as this is the absolute minimum the DM856 can work.

The PSU is overspec'd for the stepper set up as it stands, I'm using a SY57STH56-3008B Nema 23 stepper and all it does is move a few steps each way, a few times a day, then the whole lot is powered off. There's also an additional circuit added on the output of the PSU which is a Zener diode used to drop the voltage from 68VDC to 24VDC which can then be used to drive a panel mounted indicator, see here:

http://www.mycncuk.com/threads/7948-...s-and-high-VDC

No idea if this is somehow affecting the PSU over time and causing a failure? Another thing which happens fairly often is powering the kit on / off, typically 2-3 times a day, sometimes more often. There is a servo with a controller mounted on the same AC supply (it's got an AC filter mounted to reduce noise when it comes on / off), but it has it's own MCB, the SPS705 is powered via an additional switch, so even if there was some back current from the servo controller startup, the additional switch should protect the SPS705 (or so I think).

Regards,
Tom

EDIT: not got any GLS bulbs at the moment but I can order some I reckon (assuming they are still available)