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Fanuc O T lathe screen issue


Apr 11, 2014
NZ or canada
Hi all.
I just found this site and looks like some very helpful people here.

Jist bought a leadwell gt20 lathe. It was unplugged and has lost all parameters I'm pretty sure. (Unpowered for 2 hrs).
Before it was unplugged the old CRT screen died and was replaced but never gotten running. Now when I try start it I get a broken rainbow type look. One time I got some broken writing and I did get a few error codes another time starting with reset and delete held.

I'm really hoping to get it running. Graphics card was swapped by last owner, but again, still doesn't work

Thank you for your time. Feel free to explain everything like talking to a 2yrold. I have very limited knowledge of this. If I was wise I would have got a working machine.


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Jan 5, 2014
Vancouver, WA. USA
24V from the control power supply. Need to scope and look for noise. Multimeter won’t tell you that. If no scope available, it’s not expensive to just replace all the electrolytic caps in the control power supply. Make a list and put together an order at Digikey. IIRC, the last one I did was on a Fanuc 11M and the caps came to $10-$12. Many weird troubles on CNC controls result from a bad or dying power supply.