Mita xi8020 c550 code

[shady1988]

Hello dear all!
My machine when it's warm up and going round it's turn off suddenly and turn on again three times then give a code "Call for service C 550".

I had read this code in the service manual and the result like thies :

Dark potential correction
problem: out of range

The drum potential sensor
output remains at less
than A0h (650 V) when the
grid potential is increased
to larger than A0h (650 V)

during potential correction.
--- My question is: Is the machine act right by turning on and off three times?
Please help evry body>>>

[shady1988]

Sorry gays I had watch the machine well ,The machine is not turning off but it's show message as you open the fixing unit "Close fixing unit" three times then show this 'C550' code
Please try to help me evry body I'm realy hot to fix this problem!