HP 4 Plus Manual

							High Voltage Power Supply Assembly  
The High Voltage Power Supply Assembly provides the necessary
voltages for the printer’s electro-photographic processes. The
+24B VDC supply is used to power the High Voltage Power
Supply Assembly. A summary of the major components of the
high voltage system, is given in the table below (see Figure 7-18
for High Voltage PCA layout).
Checks Action
Are the connectors for the Primary
Charge roller, Drum Ground, Developing
Bias, Toner Level Sensor damaged,
corroded, dirty, or missing? Also check
the Toner Cartridge. Visually inspect each item. If any are
damaged, correct as necessary. Replace
the High Voltage Power Supply if the
connection is not repairable. Check that
all wires are connected to their
respective terminals.
Are the HVPS connections bent or
broken? Clean the terminals with alcohol only.
Table 7-29High Voltage System Checks
Troubleshooting 7-51 
						

							Interface Troubleshooting
This section provides an overview of the printer interface
requirements. Refer to Chapter 3 for detailed information about
the printer interfaces and configuration.
Communications Check 
NoteCommunication problems are normally the
customer
’s responsibility. Time spent attempting
to resolve these problems may not be covered by
the product ’s Hewlett-Packard warranty.
The Customer Service Center (CSC) is available
to the customer to help them through these
problems. The CSC telephone number is:
(208) 323-2551. 
If the printer is not connected to an MS-DOS-based host, proceed
to the Communications Checks table in this section.
Test Message 
After the printer is installed, verify communications between the
printer and the IBM-compatible computer. Enter the following at
the DOS prompt:
C:\DIR>LPT1  [Enter]
The printer should print a directory listing of the C:\ directory.  If
the Communications Check fails, proceed as follows.
7-52 Troubleshooting 
						

							AUTOEXEC.BAT Standard Configurations 
Parallel DOS Commands   
If the previous check did not produce the desired result, ensure
that the AUTOEXEC.BAT file contains the following statements
for parallel interface communications:MODE LPT1:,,P
For MS-DOS version 4.0 and above, enter: MODE LPT1:,,B
Note This example assumes that you are using parallel
printer port LPT1. If you are using LPT2 or
LPT3, replace LPT1 in the example with the
appropriate printer port.
If the problem persists, proceed to Table 7-30 
“Communications
Checks. ”
Serial MS-DOS Commands  
Most IBM compatible computers default to a parallel printer port.
To ensure that information is sent to your serial printer port, type
the following MS-DOS commands at your MS-DOS prompt, or
include them in your AUTOEXEC.BAT file. MODE COM1:9600,N,8,1,P
MODE LPT1:=COM1
For MS-DOS version 4.0, or above, enter: MODE COM1:9600,N,8,1,B
MODE LPT1:=COM1
Note These examples assume that you are using serial
printer port COM1. If you are using COM2 or
COM3, replace COM1 with the appropriate
printer port.
If the problem persists, proceed with the following checks in
Table 7-30.
Troubleshooting 7-53 
						

							Communications Checks
ChecksAction
Is your computer configured to the
parameters described in the
configuration instructions? These parameters are required to
communicate with the printer. Verify your
computer
’s communications port
configuration matches these parameters.
Note: If these parameters are not set
properly, they may yield a 40 , 20 , or
22 ERROR  on the printer ’s Control Panel.
For Serial Communications only
Does the printer ’s baud rate match that
of the computer ’s communications port? Run the printer
’s Self Test to verify the
baud rate setting. At the computer, verify
that the baud rate is set correctly in any
configuration files.
Note: A baud rate problem may cause a
40 ERROR .
Are you using the correct cable for
communications between the computer
and the printer? See the cable wiring in Chapter 3.
Hint: On an RS-232 cable, pins 2 and 3
may need to be reversed at the
printer-end of the cable.
Are you using the correct RS-232-C
protocol? During the communications 
“handshake, ”
the printer transmits both the XON/XOFF
signal, and the DTR signal. The DTR
(Data Terminal Ready) signal may be
either negative going, or positive going.
DTR polarity is set at the printer ’s Control
Panel. The XON may be set to normal
(only transmitted when data is needed),
or Robust XON (transmitted every
second). This feature is configurable from
the Control Panel. DTR is available at pin
20, and XOFF is transmitted from pin 2
of the printer.
Table 7-30Communications Checks 
7-54 Troubleshooting 
						

							If the host system and printer still are not communicating, and
steps 1 through 9 have been completed, replace the Formatter
PCA and the MIO card, and reconfigure the printer.  If the
problem persists, a protocol analyzer may be needed to find the
source of the problem.
CautionHP LaserJet printers are not designed to work
with mechanical switch-box products without
proper surge protection.  These devices generate
high transient voltages that cause permanent
damage to the Formatter PCA.  This
circumstance is not covered by the
Hewlett-Packard warranty.
Checks
Action
If using a serial interface, is the cable
longer than 50 feet (15 meters)? The maximum recommended cable
length for RS-232 serial communications
is 50 feet. Use RS-422 for the HP
LaserJet 4/4M printer, or move the
printer closer to the host.
If using a Centronics parallel cable, is it
over 10 feet (3 meters) long? Use a serial interface connection, or
move the printer closer to the host.
Do all the current Control Panel
Configuration Menu items match the host
system ’s parameters? Make appropriate changes. If host
system changes are made, be sure to
reboot the system, or otherwise ensure
the changes are in effect.
Does the printer have a bad interface
port? If possible, try a different printer interface
than the one with the problem.
Reconfigure the printer and host.
Does the host have a bad interface port? If possible, try a different host system port, and reconfigure both the host and
printer appropriately.
Table 7-30Communications Checks (continued)
Troubleshooting 7-55 
						

							MIO Troubleshooting
The Self Test Printout and explanation shown on the following
pages contain valuable information regarding the current status
of the MIO. Before attempting to troubleshoot a network problem
or notifying your network consultant of a problem, always obtain
a Self Test Printout.
Troubleshooting Hints
The JetDirect Card Status Block (see Figure 7-10, status block 2)
indicates the functionality of the JetDirect Card. An I/O NOT
READY STATUS indicates a problem. A 2-digit error code follows
the message. Use the HP JetDirect Network Interface
Configuration Guide (P/N J2552-90001) for detailed explanations
of errors and suggested corrective action. 
NETWORK STATISTICS, status block 3, indicates network
activity. Bad packets, framing errors, unsendable packet and
collisions should be minimal. If unusually high numbers of these
statistics occur, please advise the network administrator.
The various Network Operating Systems supported by these
printers are indicated in status blocks 4, 5, 6, and 7. When the
status is READY, the printer has successfully connected to the
host network server and is awaiting data. Other messages
indicate the printer is either still trying to successfully connect to
the network or a configuration problem has been encountered.
Refer to the HP JetDirect Network Interface Configuration Guide
(P/N J2552-90001) for detailed explanations of these messages.
7-56 Troubleshooting 
						

							Explanation of Self Test Printout
1Multiple Environment Information. General information
about your JetDirect MIO.
2JetDirect Card Status. I/O CARD READY indicates the
interface is correctly configured and capable of
communicating. I/O CARD NOT READY indicates there is a
problem with the interface, configuration, or server.
3Network Statistics. A list of network statistics is generated by
the JetDirect MIO. All statistic counters are reset to zero
when the printer is turned OFF.
Supported Network Operating Systems
4Novell Status Information
5Apple Ether Talk/Local Talk Status Information
6HP-UX, Solaris and Sun/OS (TCP/IP) Status Information
7Lan Server/Lan Manager/Windows for Workgroups/Windows
NT Status Information
Troubleshooting 7-57 
						

							Figure 7-10 MIO Staus Information on the Self Test Printout
7-58 Troubleshooting 
						

							Troubleshooting Aids
Component Locations
The following illustrations help you quickly find the parts
discussed in this chapter. 
12
3
4
5
5B
5A
5C
Figure 7-11 Major Assembly and Connector Locations
NumberPartNumber Part
1 Fuser Assembly 5 Paper Feed Assembly
2 Cooling Fan 5A Paper Control PCA
3 DC Controller PCA 5B Sensor PCA
4 Main Motor Assembly 5C Paper Pickup Motor (M2)
Table 7-31
Troubleshooting 7-59 
						

							12
3
4
5
6
Figure 7-12 Major Assembly and Connector Locations (2 of 3)
NumberPart
1 Laser/Scanner Assembly
2 DC Controller PCA
3 Interconnect PCA Assembly
4 Paper Control PCA
5 High Voltage Power Supply PCA
6 Exit Sensor Assembly
Table 7-32
7-60 Troubleshooting