fuser error with a good fuser

[mufka]

On a HP LaserJet 4100N, I am receiving the 50.2 fuser error message. I have tried a known good fuser in the printer, but I still get the same error. Is there something else that I can look at?

 

[hpwizzard]

50.2 is fuser warm up service error.
You might want to check the Low PSU in the printer. It has two internal fuses where one is for the fuser heating element (F1). If the fuse is blown, it will generate 50.2 error.

 

[mufka]

Fuses are ok.

 

[hpwizzard]

If the fuses are OK we must assume the power supply for the fuser is good and then the isssue would be located on the engine controller board where the fuser heater control is. If the heater control does not send a signal to activate the heating in the fuser it will also generate the 50.2 error if a thermistor is blown.

ECU schematics ->

http://www.countryfisher.com/images/temp/ecu.jpg

http://www.countryfisher.com/images/temp/ecu2.jpg

 

[mufka]

I assume that replacing the ECB would likely fix the problem. Am I correct?

 

[hpwizzard]

Yes, in case the fuser is tested to be OK along with the fuses i the PSU I would assume the fuser heater circuit on the ECU is faulty.

 

[mufka]

Just to clarify, I checked the two fuses on the ECU. Those are the ones we are talking about, right? Perhaps these components are called by different names, but I'm calling the ECU (ECB) the board that is sandwiched in the middle of the printer.

 

[hpwizzard]

Yes, there should be two fuses in the PSU part of the ECB. One of them F1 is for the fuser (also called fixing unit) The ECB or engine controller board is like you state centered in the middle of the printer. ECB is also called ECU (engine controller unit) in some manuals.