[Dean-R]

Hello Guys,
I am looking for some help with a Fanu o/t control.Recently fuse FX14 +24E has started to pop bringing up "system alarm 950 fuse break" message.I have searched for a short in this 24 V cicuit but cannot find one.the machine can run for several days no problem or can blow a fuse when sitting idle.Could it be something on the I/O board that is at fault.
Any thoughts welcome

[Shoprag]

Intermittent problems like this are always fun to find. Common short problems occur in items that move- ATC, foot switches, etc. Also look at the RS232 connector on the machine panel. Pin 25 on the DB25 port is normally wired up to 24VDC for a tape reader. If the connector on the machine comes loose, like they often do, this pin could touch the frame and blow the fuse.

[tc429]

on a horizontal lathe, I'd look in the turret and x axis limits, they usually get rusty/wet eventually...shoprags got a good point on the rs232 plug, ive seen them pretty filthy on the footswitches, also look for quick connects - we had some mori(i think) lathes with plug in footswitches, the plugs shorted out often.

eventually, hopefully it will short out hard and stay- then take a good meter that can read in hundredths of a ohm, start going from ground down the terminal strips...16.5/17.5/18.5 are decel/ot inputs, if anything is shorted 24 to ground, these will normally be also, as they are nc contacts...but with low ohm meter, just look for the lowest reading, and pull the 24 wire off that its common to...Ive had op panel lights and switches short out too...anything arcing to ground intermittently is fun.

[Dean-R]

Thanks for your input guys.Machine has not blown a fuse for a couple of days.When it does hopefully the short will remain long enough to allow me to trace.Will let you know how I get on.