C6501 C4721 then C4101

**Choclit008** · 04-04-2015

C6501 / 2.2M copies / FW GN3-70 / PM kit installed 1 week previously
The customer was printing when Black dropped out of the prints eventually popping C-4721 K write unit 12V code.
I power cycled twice with code recurring both times during power up.
Then I pulled the K write head ( 4 connectors), blew the dust off & reinstalled it.
Since then only C4101 codes come up (yellow polygon motor)
I temporarily swapped Y & M units to see if the code would follow the unit - it did not.
I was advised to check all connections on harnesses going to the write units (uplugged & reconnected) but this did not resolve anything.
I inspected the harness back to the PRCB.
I have swapped the PRCB - no change.
Started the unit in tech mode & tried to start the polygon motors for the write units but do not hear anything.
Pulled the top connector off all units (polygon wires) & powered on - same code

Seems to be a phantom code
Suggestions? I don't understand what would have caused the 2nd code

I will probably try to swap K write unit & IPB next to see what happens

**Albonline** · 04-06-2015

swap out k write unit, think it may be loading the power supply.

**Choclit008** · 04-06-2015

Thanks - will do that next

**Choclit008** · 04-08-2015

Have swapped PRCB IPB & write unit/K and still getting C4101 code.

Have confirmed continuity in harness from Y 9Pin connector to PRCB connector 651

With door open so unit does not code voltages are consistent across all write units on the 9 pin connector.

Output check does not seem to turn polygon motors on - I can't hear any noise at all.

Will order harness per KM support but I don't think I have any broken wires in it.

**blackcat4866** · 04-08-2015

How about the 12v supply? Where is it coming from, and is it consistently present? Shorting to frame ground?

On a Toshiba recently, I assisted on a toner motor issue, which after much metering of harnesses brought us all the way back to the filter board. That 5vdc lead was shorting out a 5vdc logic level, which happened to include the toner cartridge rotation sensors and the toner motors. The point of this digression is that a short can take you anywhere in the machine. There is no logic to it. =^..^=

**Choclit008** · 04-08-2015

All the voltages on the PRCB looked ok
I found 3 12V points on the wiring diag for DSCP/1, none on /2

I will give that a look in the morning - I was starting to wonder about power issues...

**Albonline** · 04-08-2015

try dcps2 24v2-2 is sourced from there, connector 127.

**Choclit008** · 04-09-2015

RESOLVED
Bad M43 fan motor that appears to spin normally was at fault.
My Service Manager decided to replace it & the C4101 code did not happen.
To test I opened the front door and plugged the suspect fan back in and code happened right after I closed the door.

After unswapping PRCB, IPB & Kwrite unit the original C4721 code came back.
Swapped the loaner K write unit back in and unit is fully useable.

Also - there are 5 fans & a TEMS/HUM unit mounted on the frame & no way to keep it off to the side so I completely disconnected it & set it aside as it did not appear to cause any fan codes which I expected to show up. This obviously is faulty logic. Don't do it.

My SM thinks it is time to replace all 5 fans -the unit has 4 & 1/2 yrs of use now & will be kept in use for the foreseeable future.

Thanks for the input and hope this helps someone else - watch out for those fans.

**blackcat4866** · 04-09-2015

Congratulations on your success. =^..^=

**tulintron** · 01-17-2018

Originally Posted by Choclit008

RESOLVED
Bad M43 fan motor that appears to spin normally was at fault.
My Service Manager decided to replace it & the C4101 code did not happen.
To test I opened the front door and plugged the suspect fan back in and code happened right after I closed the door.

After unswapping PRCB, IPB & Kwrite unit the original C4721 code came back.
Swapped the loaner K write unit back in and unit is fully useable.

Also - there are 5 fans & a TEMS/HUM unit mounted on the frame & no way to keep it off to the side so I completely disconnected it & set it aside as it did not appear to cause any fan codes which I expected to show up. This obviously is faulty logic. Don't do it.

My SM thinks it is time to replace all 5 fans -the unit has 4 & 1/2 yrs of use now & will be kept in use for the foreseeable future.

Thanks for the input and hope this helps someone else - watch out for those fans.

PERFECT! I came across a similar problem and I was able to solve it after reading your post !!!