HP Laserjet 4 Manual

Drum Rotation Functional Check   .  .  .  .  .  .  .  .  .  .  .  7-50
High Voltage Power Supply Assembly    .  .  .  .  .  .  .  .  7-51
Interface Troubleshooting  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  7-52
Communications Check   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  7-52
Test Message   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  7-52
AUTOEXEC.BAT Standard Configurations   .  .  .  .  .  7-53
Parallel DOS Commands     .  .  .  .  .  .  .  .  .  .  .  .  .  ....

Removing the Paper Guide Assembly  .  .  .  .  .  .  .  .  .  A-16
Removing the Paper Roller  .  .  .  .  .  .  .  .  .  .  .  .  .  .  A-17
Removing the Control PCA   .  .  .  .  .  .  .  .  .  .  .  .  .  .  A-20
Removing the Power PCA  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  A-22
Removing the Holding Tray Center Paper Guide  .  .  .  A-23
Removing the Holding Tray Belt  .  .  .  .  .  .  .  .  .  .  .  A-24
Removing the Holding Tray Paper Sensor    .  .  .  .  .  .  A-26
Removing the Switchback...

To Print Using the Infrared Port .  .  .  .  .  .  .  .  .  .  .  .  B-36
Troubleshooting IR Printing Problems  .  .  .  .  .  .  .  .  B-38
Infrared Port Not Responding  .  .  .  .  .  .  .  .  .  .  .  .  .  B-41
Contents-9 

Contents-10 

1
Product Information
Features HP LJ 4 HP LJ 4M HP LJ 4 Plus HP LJ4M Plus
Model C2001A C2021A C2037A C2039A
Printer Speed 8 ppm 8 ppm 12 ppm 12 ppm
Resolution 300/600 dpi 300/600 dpi 300/600 dpi 300/600 dpi
Expandable I/O Buffer No No Yes Yes
Resource Savings No No Yes Yes
MEt No No Yes Yes
REt Yes Yes Yes Yes
Languages Enhanced PCL5 Enhanced PCL5,
Postscript Level 2Enhanced PCL5 Enhanced PCL5,
Postscript Level 2
PostScript Upgradeable C2080A* N/A C3129A* N/A
Resident Memory 2 MByte 6 MByte 2 MByte 6...

Product Family Information
The model HP C2021A is identical to the model HP C2001A from
a hardware standpoint, as is the model HP C2039A to the model
HP C2037A. The models HP C2021A and C2039A printers
include the following features:
•PostScript Level 2 SIMM
•AppleTalk MIO Card
•4 MBytes of RAM
In every instance the repair procedures for all products are
similar.
Some LaserJet 4 accessories are compatible with the LaserJet 4
Plus and some are not. The compatibility chart below may be
used when there is a...

Identification    
The model number is on a label placed on the outside, rear cover
of the printer. The model number (C2001A, C2021A, C2037A or
C2039A) is found at the top of the label. The model number is the
base number for all printers.  
The serial number contains information about the printer
Country of Origin. The serial number Alpha section refers to the
Country of Origin, the Revision Level and the Production Code.
The Numeric section refers to the production number of the
printer. See the...

Figure 1-2 Printer Identification Label for the HP LaserJet
4/4M
1-4 Product Information 

Specifications 
HP LaserJet 4 and 4 Plus
Dimension HP LaserJet 4/4M
(C2001A/C2021A)HP LaserJet 4 Plus
HP LaserJet 4M Plus
(C2037A/C2039A)
Width 16.4 in (416 mm) 16.4 in (416 mm)
Depth 15.9 in (403 mm) 15.9 in (403 mm)
Height 11.7 in (297 mm) 11.7 in (297 mm)
Weight (with toner cartridge) 37 lbs. (18.3 kg) 37 lbs. (18.3 kg)
Table 1-3Printer Dimensions
Watts (typical)
Volts Freq 4/4M 4 Plus/4M Plus
100 Vac ± 10%
120 Vac ± 10%50/60 Hz ± 2 Hz
50/60 Hz ± 2 Hzprinting = 195
standby = 55printing = 300
standby =...

Status 100/115 V
4/4M    4 Plus/4M
Plus220/240 V
4/4M    4 Plus/4M
Plus
Product Rating 6.4 amps     7.8 amps 3.1 amps     4.0 amps
Peak Inrush Current 22 amps     22 amps 22 amps     22 amps
25% Decay Time 13 msec     18 msec 11 msec     11 msec
Peak Fuser Current 38 amps     51 amps 17 amps     22 amps
Return-to Average Time  200 msec     200 msec 200 msec    200 msec
Table 1-6Electrical Specifications
Operating EnvironmentTemperature: 10° C to 32.5° C (50° F to 90.5° F)
Humidity: 20-80% (no...