HP 5 C3916A, C2021A, 5n C3952A, 5m C3917A, 4 C2001A Service Fuser Malfunction Checks, Checks Action

Table 7-10		50 SERVICE Fuser Malfunction Checks
	Checks		Action
Is the Fuser Assembly correctly			Reseat the Fuser Assembly. Allow
seated?			adequate time for the error message to
			clear (10 minutes) and turn the printer
			ON.
Is the Fuser Bulb/ Thermoswitch open?			The fuser bulb and thermoswitch are
			wired in series. To check if one or the
			other is defective, perform the following:
			1. Remove the Fuser Assembly from the
			printer.
			2. Use an ohmmeter and measure the
			continuity between pins (see Figure
			7-6, callout 1). It should read about 2
			ohms (about 4 ohms for the 220 volt
			fuser). If an open condition is detected,
			either the fusing bulb or the
			thermoswitch is defective. Replace the
			defective component (refer to Chapter
			6) or replace the complete Fuser
			Assembly.
Is the Thermistor defective?			1. Remove the Fuser Assembly and let it
			cool to room temperature.
			2. Use an ohmmeter and measure the
			resistance between pins (see Figure
			7-6, callout 2) It should read about 220
			K ohms +/- 40 K ohms at ambient
			room temperature. If the thermistor is
			either open or shorted, replace the
			thermistor (refer to Chapter 6) or the
			complete Fuser Assembly.
Does the error persist?			1. Verify all cabling is correct.
			2. Replace the following components in
			the order given:
			Power Supply Assembly
			DC Controller PCA

See Figure 7-11 for Fuser Assembly location and Chapter 6 for removal and replacement, as necessary.

N o t e	The 50 SERVICE error message can be cleared
	immediately by shorting the C202 leads on the
	HP LaserJet 4/4M (or the C205 leads on the HP
	LaserJet 4 Plus/4M Plus/5/5M/5N) on the DC
	Controller. Remove the Formatter PCA to access
	the DC Controller as shown in Chapter 6.

7-30 Troubleshooting