Here are some issues that can happen Fadal machines and some tips to solve your issues. Typically this happens on early Fadal machines that the control cards were updated, but did not receive all the wiring upgrades found on newer Fadal cabinets.
Issue:
is running in Auto, and the machine will randomly go into SLIDE HOLD
A keypress will be missed. When typing X10.222 but the zero is skipped
Jog wheel loses pulses when turning the MPG
Jog mode issues
Possible solutions:
check the 1090 keyboard control revision. If it is not at least the 1090-3A board, which has filter capacitors and a removable software EPROM, then this is definitely the root problem. Update to at least the 1090-3A with the latest software, this is usually the solution that directly addresses the problem
Fadal increased the gauge of the +5 and DC ground wire going the 1090 power terminal. Fadal ended up using a very large gauge red and white/black wire to power the 1090. At least 12 AWG. This improved the voltage drop all the way to the pendant as well and improving the noise on the DC ground.
Improve the chassis green ground wires by increasing gauge, reference a late 1990s built Fadal electrical cabinet the used larger gauge wire as well as single point chassis grounds.
The keyboard signals are on a 26 wire parallel cable that goes back to the 1060 motherboard. Make sure this cable does not run next to any high power wires. Look at the bundle in the top cable tray over the machine, remove it from the bundle if it is wire tied into other wires.
Make sure the Feed rate and Spindle % pots aren't shorting onto the front panel. This can create odd intermittent problems. Look for shorts to the panel with a multi-meter. Look for improvements by disconnecting the 2 pots from the panel so they hang in the air not touching anything. If the issues improve, look for where the short on the panel.
With a new 527F control upgrade, purchase the Calmotion version of the 1090. The 26pin parallel cable can be replaced with a much more robust RS-485 serial connection using CAT5 cabling. Contact Calmotion with a picture of your current 1090 card and the set of 527F control cards in the 1060 motherboard. Calmotion will help selecting the correct parts to update the keyboard controller.