HP Laser Printer 50.x Fuser Errors - What caused them -How to fix them

HP LaserJet 50.x errors are common for all laser printers and in most cases, caused by the fuser. A 50 service tells you that the printer did not reach operating temperature in a specified amount of time. The older printers use a halogen lamp & teflon rollers with a thermistor to sense roller temperature, and a thermo switch that pops open as a one time fuse if it overheats. The newer style fusers use an instant-on ceramic heating element covered by a teflon sleeve. Either the lamps or the heating elements can break if dropped. We ship all our fusers in custom made foam end caps to ensure shipping damage does not occur. All fusers run off the 110v ac power from the wall outlet. This comes from the low voltage power supply ( LVPS ) which turns on/off power to the fuser as needed to heat the lamps or heating element. If your printer displays a 50 service error or fuser fail error code you can test it with an ohm meter, if it reads OK, the trouble is most likely the ac power supply (LVPS). For more detailed information by printer mode see below

HP LaserJet 50.x Fuser Errors

50.1 fuser error	Fuser low temp
50.2 fuser error	warm up failure
50.3 fuser error	over temp
50.4 fuser error	bad ac line voltage or fuser *
50.5 fuser error	wrong type fuser installed *

*Please note the HP 4200/4250/4300 are not interchangeable - If the wrong fuser is installed in the wrong printer it will give a 50.4 or 50.5 fuser error. Check the part numbers on the fusers match RM1-xxxx .

HP LaserJet 4200/4240/4250/4300/4345/4350

All these fusers look the same and unfortunately can be installed in the wrong printers. Find the part number listed below on the old fuser and make sure it matches the replacement.

Part Number	Printer
RM1-0013	HP 4200
RM1-0101	HP 4300/4345 *
RM1-1043	HP 4300/4345 *
RM1-1082	HP 4240/4250/4350

RM1-0101 and RM1-1043 are interchangeable

HP LaserJet 4/4+/5:

Most likely an open lamp, possibly open thermo switch, not likely but could be the low voltage power supply or DC control board.

HP LaserJet 4000/4100/5Si/8000:

Power off printer, remove and re-install fuser. If error returns test or replace fuser. The 4000/4050 use self tapping screws and can easily strip the plastic - do not over tighten.

HP LaserJet 8100/8150:

50.1 fuser error - is most likely a bad low voltage power supply (LVPS) RG5-4357 which is a common failure on these printers. All other fuser errors with these models are usually caused by a defective fuser

HP LaserJet 5P/6P:

This printer used a secondary error code. A fuser fail is indicated by top LED ON in both primary and secondary states. To see the secondary state press "GO" and "Reset"

HP LaserJet II/IID/III/IIID:

The ac power supply is most likely bad, test the fuser lamp it's probably OK. There are two versions of power supplies. One that runs the fan with the printer on and one that only runs the fan when printing. If the fan dies you will NOT get an error which can then take out the power supply and/or the fuser. Test the fuser lamp and thermo switch for opens if it reads good replace the ac power supply.

HP LaserJet 3Si/4Si:

Most likely the fuser, but could be the AC power supply. Hope it's the fuser not the power supply because you will have to tear down the printer pretty far to replace the power supply. 50 Service errors are not vary common with these printers.

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