Brother MFC 9420CN Color Laser Printer

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I'm trying to repair this multifunction color laser printer / copier /
fax / scanner. The person who gave it to me indicated it needed a new
OPC belt. Sure enough, when powered up it gives a message "No OPC
Belt. Install OPC Belt" Unusual, the normal message is "Replace OPC
belt". Once I found out how to replace the OPC belt, I discovered the
belt was already present. And I discovered the tension release pins
on the belt cartridge were still inserted (they are to be removed
before installing the cartridge).

Since a new belt costs in excess of $200, I would prefer to establish
the cause of the error message before spending that much money. There
are no obvious pressure or optical switches to detect the presence of
the OPC belt. Does anyone have any experience servicing these?

PlainBill

 

[circuit]

That means the photodiode or whatever they are using to detect the presence
of the opc belt is not being triggered. Could be toner on the sensor, or
the release pins may be somehow preventing the detection.

 

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Remove the pins.

Already done.

Do a factory reset.

'Factory reset?' I've reset the OPC counter, and checking the other
counters(page, drum, fuser), they all appear to have been reset. Is
there one I've missed?

PlainBill

 

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That means the photodiode or whatever they are using to detect the presence
of the opc belt is not being triggered. Could be toner on the sensor, or
the release pins may be somehow preventing the detection.

My idea also. However, the presence of a microswitch is non-obvious,
and there are no signs of optical sensors present. Or maybe I've been
barking up the wrong tree. I've been thinking in terms of a detector
that would be blocked by the cartridge. Perhaps a reflective sensor
that detects the presence of a cartridge. Thanks, some good ideas.

PlainBill

 

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Ooops. That won't work with the MFC 9420CN. It has a chip on the OPC
cart. See:
<http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=120501369126>
for a replacement.

I still think it's a bad insertion sensor (microswitch) or cable
connector.

Note that the chip is usually a PCB with a chip wire bonded or glued
to the PCB and covered with epoxy. I destroyed one by pushing on the
epoxy. They're quite fragile.

Thanks,

I'll see if I can locate anything. You sugestion of an incorrect
cartridge is also worth looking into.

PlainBill