I've been puzzling over this one a almost a month now -- a client has a Aficio Color 4006, along with the Fiery module for allowing the system to be used as printer. The machine has been (what appears to be) powering off totally - the fans die, the control panel etc. All except for the fan in the Fiery unit. Initially I stripped the system down, checked the connections on the PSU board, thermister connections, etc. I removed a small amount of torn paper form the fuser, but other than that, nothing unexpected. All was fine for more than three weeks, but I got a report last week that the problem had reappeared.
I stripped the machine down again, and did some investigation.
There were a couple of unrelated SC's being logged, specifically to do with the sorter, which I've fixed, however, the machine still powers off.
I removed the fiery unit totally (I see why the fan on it remains on -- the unit has a seperate power supply, which is fed directly off the mains switch, thereby byp*ssing the actual main PSU), and started checking voltages etc at the PSU - however, as soon as I try and probe them, the copier switches off - exactly the same as what happens when it switches off on its own (yes, I have checked all the auto power off timers, etc).
It seems to be more common when the machine is cold, and warming up -- once it has warmed up it seems to work.
I did, however, observe that the hot roller (fuser) is heating up quicker than the pressure roller (and as such, the hot roller heater is switching off, the pressure roller one is still on, and the hot roller temperature keeps climbing for a bit). The highest I saw the temperate at was around 166 - now, I know the temperature cut out on the fuser is around 167 - 170, but I do not know what sort of cut out it is (does it totally power the system down, or does it through a SC?).
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