Check the 5 volt, you can addapt it with potmeter R116
or recheck BRDG21

Reset Circuitry:
The I/O will reset in three (3) cases:
1. The CPU is in reset. The CPU’s reset signal is fed into the I/O through connector J1 and forces
the I/O into reset.
2. The 5v supply has fallen below 4.75v.
3. The watchdog is not being fed by the scanning of the light matrix. More specifically Pin-19 of U6
must be toggling once every 50ms to prevent the watchdog from resetting. The scanning of the
light matrix is controlled by the CPU through J1.

LED L204 shows the reset state of the I/O Board. If this LED is not lit either the 5v DC is below 4.75v or the
CPU/Sound Board is holding the I/O in reset. If the LED is flashing this means that the watchdog is not being feed
by the CPU/Sound Board and the I/O is oscillating into and out of reset. If the LED is continuously on the board is
out of reset and communication from the CPU to the lamp matrix is confirmed. Testpoint Blanking is the actual
reset signal on the I/O Board. A low voltage indicates that it is in reset this will turn off all Solenoid (Coil) Drivers,
Flash Lamps, Lamp Matrix Drivers, Auxiliary Outputs and Flipper Outputs. A high voltage indicates that it is out of
reset and normal operation can take place.

Hope this helps