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Fanuc Wire EDM Pulse Encoder Alarm


Oct 31, 2015
Just recently our Fanuc Wire EDM W1 (1990-03) developed a pulse encoder alarm. We had just finished moving the machine and we switched it on for the first time when up came a '317 X ABS. Pulse Coder' alarm. I hit reset and the alarm cleared. After that I ran a G28 and referenced the machine and after that I rebooted and it worked just fine, no alarm. I then set it up on a job which ran overnight and shutoff on automatic. In the morning when I switched it on again the screen was fragmented, mostly black with fragments or thin strips of colours spread across the screen(it's a replacement LCD for CRT screen from DNC Electronics here in the UK). Anyway, rebooted the wire and the screen was fine and I carried on with the next job. It started running then suddenly stopped, with the used wire bin still running but no machining and no response from the panel by the screen. The machine couldn't be reset, nothing worked. I rebooted the machine and the screen came back fragmented as before but this time the machine was completely unresponsive, nothing worked. Rebooting made no difference, same fragmented screen, same unreponsiveness.
We did see a red LED on the motherboard, just below a green one. We checked the PSU on the floor of the cabinet, that was showing 24v as it should. Plus, there was an SPA8 connector disconnected from the Remote Buffer board but it looked like it had been disconnected for a long time. Still, my boss decided to plug it back in and suddenly it booted back up perfectly. Then he disconnected it again and still it started fine. Everything now works just fine, panels all working, machine moving etc. The red LED on the m/board has also gone. Haven't tried machining yet, that will be next Monday, but just getting it booted back up was a step forward.

During this time I was in conversation with a Wire EDM expert on the phone and he was just as perplexed by the problem and the solution.

Does anyone know what the Remote buffer board does?
What is the SPA8 connector and would disconnecting it make any difference?
Why did I get the Pulse Coder alarms?

Attached some photos so you can see the alarms etc.

Any thoughts welcome.


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