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Test of I/O Board P2 Operations


Cast Iron
May 29, 2014
ca, US
One check that I made for the gears not changing was to see if the output to the gear change solenoids was working. This checks from P2 connector to the optical coupler, to the Triac, to the solenoid. The connections in P2 control the Tool Changer In/Out, Carousel CW/CCW, High Gear, Low Gear, Spindle Unclamp and Lock. With the machine powered up all these can be checked with a battery and socket pins. I used a 7.2V nicad pack. The normal voltage on these pins is 12VDC.
Each row of the P2 pins is one function, from top to bottom: TC In, TC Out, TC CW, TC CCW, High G, Low G, Unlock and Lock. The left pins are NEGATIVE polarity, the right are POSITIVE. If you get this backward you will likely destroy the relay diode and LED unless you put a resistor in one line to limit the current. The diode is a 1N4004 and most any generic red LED will work as replacement.
I had a polarized connector between the battery and socket pins so I could move the pins around without applying power.
With the machine powered, check the diagnostics page for the switch positions. Mine was in high gear so the first thing I wanted to do is change to low gear. With the pins on the sixth row from the top I plugged in the battery and the gearbox changed gears and ran the spindle to confirm. Next I moved the pins to the fifth row (high gear) and tested again. The gearbox changed to high gear.
If you are checking the tool changer In/Out, BE SURE the spindle is up out of the way and there is no tool in the pocket.