50.4 Error

HP Color LaserJet 8500 and 8550 Series Printers - 50.4 Error Displayed on the Control Panel

A 50.4 error displayed on the HP Color LaserJet 8500 or 8550 series printer indicates that the fuser is reporting an error condition to the DC controller. The fuser has a temperature range in which it is designed to operate. If the fuser becomes too hot or fails to attain the correct temperature, a 50.x error will appear on the Control Panel. Troubleshooting this error involves a process of elimination, starting with the most common cause which is normally fuser related.

The following can cause 50.4 errors:

The fuser experiences a temporary spike in temperature. As a safety feature the DC controller will trigger the 50.4 error on the control panel, and the printer will not print.

Printing on some kind of unsupported media, usually transparencies, are wrapped up in the fuser. Once it gets bound up and will not turn, the printer will display a 50.4 error.

An issue with the power circuit for the printer can cause a 50.4 error. Any interruption, inconsistency, or lack of sufficient voltage to the printer can trigger a 50.4 error.

An incorrectly installed main driver gear assembly.

Besides the fuser, an issue with any of the following parts could cause these problems:

High voltage converter 2 PCA

AC power supply

Connector holder assembly

DC controller

Other 50.X errors

For any other 50.X errors other than 50.4 see the section titled "Other 50.X errors."

Transparency information

The HP Color LaserJet 8500 and 8550 series printers support the following types of transparencies:

HP Transparency film, letter sized (50 sheets), part number: C2934A

HP Transparency film, A4 size (50 sheets), part number: C2936A

3M Transparency film, letter size (50 sheets), part number: CG3700

Refer to the following sections for instructions on isolating the issue and repairing the printer.

Parts required (part numbers are subject to change)
Part description
Part number

Fuser (120v)
C7096-69012

High voltage converter 2 PCA
C3983-69008

AC Power Supply
C3983-69009

DC Controller
C3983-69006

DC Controller (8550 MFP only)
FG2-9470-040CN

Terminator (8550 MFP only)
FH2-6455-000CN

Connector Holder Assembly
RG5-3030-000CN

Verifying how the error occurred

Media jam in the fuser

If the error occurred because of a media jam in the fuser, turn the printer off.

Remove the fuser, and inspect it for damage.

Look inside the printer, and inspect the brown gear that mates with and drives the fuser.

If it is damaged or missing teeth, refer to bpl90028 for instructions on replacing the main gear assembly. If the fuser is damaged, replace it.

No media jam in the fuser

It is very important to find out how and when the error occurred. Has someone recently worked on the printer?

Find out what was printing at the time.

If the error occurred for no apparent reason in the middle of a job, turn off the printer, and unplug it from the wall outlet.

Leave it unplugged for 20 minutes. This will allow the DC controller to reset.

Remove the fuser after the printer has cooled down.

Measure the resistance with an Ohmmeter on the connector shown in Figure 1.

NOTE: If the fuser is hot when a measurement is taken, the reading will be high.

Figure 1:Locating the fuser connectors

1 -Ohmmeter to measure resistance between the two prongs

Locate the two prongs on the left-inside corner of the left connector. Measure the resistance between the top and bottom prongs (see Figure 1, call-out 1). The resistance will read 2.3 to 2.6 ohms if the fuser is good. If a reading cannot be taken, the thermal switch is blown, and the fuser will require replacement. If the fuser tests okay, the next step is to remove the back cover of the printer.

After removing the back cover, locate the connector that goes from the connector holder assembly to the AC power supply. See Figure 2, call-out 1. The connector holder assembly is the black plastic assembly that the fuser plugs into when it is installed in the printer.

Figure 2:Connector from connector holder assembly to AC power supply

1 -Ohmmeter to measure the resistance between one black and one white wire in the connector

There are two black wires and two white wires in the connector. Use an ohmmeter to measure the resistance between one of the white and one of the black wires. The resistance will read, 2.3 to 2.6 ohms, if the connector holder assembly is good. See Figure 2, call-out 1. If no reading can be taken (the reading is open), the assembly will require replacement.

Replacing the connector holder assembly

Locate the connector holder. The connector holder is a large black plastic piece that the fuser plugs into. It also has the PS-5 sensor as part of the assembly.

Replacing this assembly is very involved. First, the main drive gear assembly must be removed.

After removing the main drive gear assembly, one screw must be removed before sliding the connector holder assembly out of the printer. See Figure 3, call-out 1.

Figure 3:The screw to remove connector holder assembly

1 -Screw

If the fuser and the connector holder assembly test okay, the following three parts require replacement at the same time. See the next section for additional help with this.

High voltage converter 2 PCA

DC controller

AC power supply

NOTE: When removing and reinstalling the Main Drive Gear Assembly it is imperative to follow the removal and replacement instructions. The printer shown in Figure 4 had the main drive incorrectly replaced; the delivery drive assembly had not been removed prior to removal of the main drive assembly.

Incorrectly installed main drive gear assembly

The following picture illustrates an improperly installed Main Drive Gear Assembly that caused 50.4 error messages. After removing and reinstalling the assembly, the 50.4 error message was resolved. Note the gap between the Main Driver Gear Assembly and the chassis fire wall, as there is a 1/8-inch gap.

Figure 4: Incorrectly installed main drive assembly

The AC power supply is shown in Figure 2. Make sure to reconnect all connectors on the top of the power supply after replacing it.

Other 50.X errors
For the following 50.X errors the same troubleshooting as for a 50.4 error should be performed.

50.1 errors are fuser low temperature errors. This means the fuser never gets up to operating temperature.

50.2 errors are fuser warm-up errors. The fuser is not able to come up to normal operating temperature.

50.3 errors are fuser-overheating errors. This indicates the fuser is getting too hot.

© 2005 Hewlett-Packard