Kyocera TASKalfa 420i Service Manual page 205

Code
F090 Fax control PWB communication
error
F278 Power supply in drive system error
Contents
Causes Check procedures/corrective measures
Defective main Replace the main PWB and check for cor-
PWB. rect operation.
Main power switch Turn on power.
was turned off with- (To switch off power, first press the power
out using the key until the main power indicator goes off,
power key, or a then turn the main power switch off.)
power failure has
occurred.
Remarks
2KR/2KS
1-4-47