MX-5070 H4-01

[moose55]

I had a connector on the PCU PWB break while trying to remove it (CN13). I replaced the wire harness and now I will get the H4-01's after it sits for about 10-15 minutes. The fuser is heating up. I have replaced the fuser, PCU PWB, wire harness and AC PWB. I am out of ideas? Any suggestions would be greatly appreciated. Unfortunatley we do not have a similar machine in the shop to swap boards off of.

[spanky]

Clean the connection where the fuser connects to the copier when the fuser is pushed into the machine.

Thermistors work by measuring the resistance and a little dirt or dust can change that resistance.

[harleyrider]

Try this. 1-Remove fuser unit. 2-Close all covers power on the machine with the fuser out. 3-Wait 10 seconds "check fuser unit" should be displayed and then power off machine. 4-Install fuser and power on machine. Hope it helps

[mojorolla]

Try this. 1-Remove fuser unit. 2-Close all covers power on the machine with the fuser out. 3-Wait 10 seconds "check fuser unit" should be displayed and then power off machine. 4-Install fuser and power on machine. Hope it helps

Yep, this is a known issue for the PCU board on this model. Make sure it has the grounding strap installed. If you do not remove the fuser, the values can get corrupted with PCU replacement and cause this code.

[repn1999]

Make sure the firmware is up to date as well. There was a bulletin for firmware update for h4-xx codes on that series.

[moose55]

Thanks guys! Resolution was a connector on the AC PWB had a loose wire in it. Reconnected wire (firmly) and all is good.