Ricoh D093 Service Manual page 271

If the breaker switch is covered with soot, this could indicate that the breaker switch
has been damaged.
To prevent damage to the breaker switch, installation of a voltage stabilizer (constant
voltage transformer) is recommended for work sites where there is significant
fluctuation in the AC power source.
Re-installation
Be sure to re-connect the breaker switch correctly.
The harnesses are color coded:
The machine will not operate if these connectors are re-connected incorrectly.
SM
Brown, Blue, Black,
5-89
Boards
White.
D093/D094