Mitsubishi Inverter fault diagnosis

Hi

Wondering if anyone can help diagnose a problem with my inverter. It is a Mitsubishi E500 and has worked flawlessly for 10 years or so. I have it connected to a large 4 pin socket so that I can swap it between my lathe and mill.

It now only works very intermittently. When I power it on fans start as they always have with 0.00Hz on the display. When I lift the lever to start either machine the motor buzzes loudly the hertz figure increases but the motor doesn't start. If left buzzing it will "trip" and show OL on the display. This behaviour is replicated when connected to either the lathe or mill which makes me think I can rule out the machine motors as being faulty. Nothing has been disturbed or changed recently.

There are two links below to short clips of the motor noise and the inverter display.

Any assistance would be appreciated, thank you.

Kevin

https://youtube.com/shorts/Vl1CJuadBUk?feature=share

https://youtube.com/shorts/mcxUKomEvmY?feature=share

Page 183 of the manual says:

Dave

Thanks for taking the time to reply. I have checked all terminal connections and they're tight. The switch over socket is wall mounted. I have rattled, pulled and twisted the cable between the VFD and socket but the symptoms are the same. I haven't tried the multimeter yet but will next weekend.

Since your reply another fault code has appeared on the E500 - E.LF but only when connected to the lathe! This is an open circuit on phase U.V.W load side.

I'm wondering if I have two gremlins - a faulty motor on the lathe and an intermittent fault in the switch box (on/off switch or speed potentiometer) for the VFD?

Kevin