Lexmark C760 Service Manual

							
Diagnostic aids3-21
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DRAM Test
This test checks the validity of DRAM, both standard and optional. The test writes patterns of data to DRAM to 
verify that each bit in memory can be set and read correctly.
To run the DRAM Test:
1.Select DRAM Test  from HARDWARE TESTS in the Diagnostics mode.
The power indicator  blinks indicating the test is in progress.
2.Press  Return  or Stop  to exit the test.
P:###### represents the number of times the memory test has passed and finished successfully. Initially 
000000 displays with the maximum pass count being 99,999.
F:##### represents the number of times the memory test has failed and finished with errors. Initially 00000 
displays with the maximum fail count being 99,999.
Once the maximum pass count or fail count is reached, the test is stopped, the power indicator turns on solid, 
and the final results appear. If the test fails, SDRAM Error appears for approximately three seconds and the 
failure count increases by 1.
CACHE Test
The CACHE Test is used to verify the processor CACHE is functioning properly.
1.Select  CACHE Test  from HARDWARE TESTS in the Diagnostics mode.
The machine initiates a POR of the printer and the following screen is displayed:
Upon completion of the POR the following screen is displayed:
P:###### represents the number of times the CACHE test has passed, finished successfully. Initially 000000 is displayed. The maximum pass count is 999,999.
F:###### represents the number of times the CACHE test has failed, finished with errors. Initially 000000 is displayed. The maximum fall count is 999,999.
2.To exit the test, turn the printer off.DRAM Test 128M
P:###### F:#####
Resetting the 
Printer
CACHE Test x100
P:###### F:###### 
						

							
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ROM Test
The ROM memory test is used to check the validity of the controller board code and fonts.
To run the ROM Test:
1.Select ROM Test  from HARDWARE TESTS in the Diagnostics mode. 
P and F represent the same numbers for DRAM. The power indicator  blinks indicating the test is in 
progress. The test runs continuously.
2.Press  Return  or Stop  to exit the test.
Each time the test finishes, the screen updates with the result. If the test passes, the Pass Count increases by 1, 
however if the test fails, one of the following messages appears for approximately three seconds: ROM Checksum Error
ROM Burst Read Error
Once the maximum pass count or fail count is reached, the test stops with the power indicator on solid. The final 
results display.
Parallel Wrap Test
Use this test with a wrap plug to check operation of the parallel port hardware. Each parallel signal is tested.
To run the Parallel Wrap Test:
1.Disconnect the parallel interface cable and install the wrap plug (P/N 1319128).
2.Select the  Parallel Wrap Test  from HARDWARE TESTS in the Diagnostics mode.
The power indicator  blinks indicating the test is in progress. The test runs continuously until canceled.
Each time the test finishes, the screen updates. If the test passes, the Pass Count increases by 1, however if the 
test fails, one of the following messages appears for approximately three seconds: Sync Busy Error
Byte Interrupt Request Error
Strobe Interrupt Request Error
Init Fail Error
Init Busy Error
Init Rise Error
Host Busy Error
RAM Data FF Error
RAM Data AA Error
RAM Data 00 Error
RAM Data 55 Error
DMA Count Error
DMA Address Error
DMA Interrupt Error
DMA Memory Error
DMA Background Error
Clear Init Rise Error
False Init Rise Error
Autofeed Rising Interrupt Error
Clear Autofeed Rise Error
False Autofeed Rise Error
Autofeed Falling Interrupt Error
Clear Autofeed Fall Error
Once the maximum count is reached the test stops, the power indicator goes on solid and the final results are 
display. Press  Return or Stop  to exit the test. 
						

							
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Serial Wrap Test
Use this test to check the operation of the Serial Port Hardware using a wrap plug. Each signal is tested.
To run the Serial Wrap Test:
1.Disconnect the serial interface cable and install the wrap plug.
2.Select the appropriate  Serial Wrap Test from HARDWARE TESTS in the Diagnostics mode. Values 
include  Serial Wrap , Serial 1 Wrap , Serial 2 Wrap,  or Serial 3 Wrap . P and F represent the same 
numbers for DRAM.
The power indicator  blinks indicating the test is running.
3.This test runs continuously unless canceled by pressing  Return or Stop .
Each time the test finishes, the screen updates with the result. If the test passes, the Pass Count increases by 1, 
however if the test fails, one of the following failure messages appears for approximately three seconds and the 
Fail Count increases by 1: Receive Status Interrupt Error
Status Error
Receive Data Interrupt Error
Transmit Data Interrupt Error
Transmit Empty Error
Threshold Error
Receive Data Ready Error
Break Interrupt Error
Framing Error
Parity Error
Overrun Error
Data Error
Data 232 Error
Data 422 Error
FIFO Error
DSR Error
DSR PIO Error
DSR Interrupt Error
CTS Error
CTS PIO Error
CTS Interrupt Error
Once the maximum count is reached the test stops. The power indicator goes on solid and the final results are 
displayed. 
Press  Return  or Stop  to exit the test. 
						

							
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DUPLEX TESTS
Duplex Quick Test
This test verifies if the Duplex Option Top Margin is set correctly. This test prints a duplexed version of the Quick 
Test Page that can be used to adjust the Top Margin for the back of the duplexed page. You can run one 
duplexed page (Single) or continue printing duplexed pages ( Continuous) until Return  or Stop  is pressed.
You must use either Letter or A4 paper.
To run the Duplex Quick Test:
1.Select  Duplex Quick Test  from DUPLEX TESTS in the Diagnostics mode.
2.Select Single or Continuous . 
The single Duplex Quick test cannot be canceled.
The printer attempts to print the Quick Test Page from the default paper source. If the default paper 
source only supports envelopes, then the page is printed from Tray 1.
Check the Quick Test Page for the correct offset between the placement of the first scan line on the 
front and back side of a duplexed sheet.
If adjustment is necessary, the Top Margin in the Registration menu must be adjusted first. The 
Duplex Top Margin Offset may be adjusted next.
A positive offset moves the text down the page and widens the top margin, while a negative offset 
moves the text up the page and narrows the top margin.
3.Press Return  or Stop  to exit the test.
Duplex Top Margin Offset
Modification of this setting controls the offset between the placement of the first scan line on the front and back 
side of a duplex sheet.
Changing the value by 1 unit moves the margin by 1/100 inches. A positive value moves the text down the page 
and widens the top margin. A negative value moves the text up the page and narrows the top margin.
Duplex Sensor Test
This test determines whether or not the duplex sensors and switches are working correctly.
1.Select  Sensor Test  from DUPLEX TESTS in the Diagnostics mode.
2.Select the sensor to test:
Duplex input sensor
Duplex exit sensor
3.Manually actuate the duplex sensors. When the sensor/switch is closed,  CL (closed) displays, when the 
sensor/switch is open,  OP (open) displays.
4.Press  Return  or Stop  to exit the test. 
						

							
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INPUT TRAY TESTS
Feed Test
This test lets you observe the paper path as media is feeding through the printer. The upper front door, used to 
access the print cartridge, cannot be opened during the feed test. To observe the paper path, you must open the 
lower front door, used to access the paper jams on the vacuum transport belt. Blank pages feed during the test.
Note:  This test can run using any of the paper or envelope sizes supported by the printer. The pages are placed 
in the default output bin, however, the Feed Test menu lets you select the input source.
To run the Input Tray Feed Test:
1.Select  Feed Test  from INPUT TRAY TESTS in the Diagnostics mode.
2.Select the input source from the sources displayed on the Feed Test menu. All installed sources are 
displayed.
3.Select either  Single (feeds one sheet of media from the selected source) or  Continuous (continues to 
feed from the selected source until  Return or Stop  is pressed).
4.Press  Return  or Stop  to exit test.
Sensor Test
This test can be used for either 500-sheet trays or 2000-sheet trays.
500-sheet trays
Use this test to determine if the input tray sensors for a 500-sheet tray are working correctly.
To run the Sensor Test for 500-sheet trays:
1.Select the  Sensor Test  from INPUT TRAY TESTS in the Diagnostics mode.
2.Select the input source from the sources displayed. All installed sources are displayed. 
For example, Tray 1 may appear as follows:
L1=Input Tray level/empty Sensor 1
L2 =Input Tray level/empty Sensor 2
P =Input Tray Pass Thru Sensor
Not all sensors display for all trays. Tray sensors are supported by the following sources:
3.Manually actuate each sensor. The tray empty sensor can be actuated by hand, however a sheet of paper 
can be used to cover the pass thru sensor. When the sensor is closed,  CL displays, when the sensor is 
open,  OP appears.
4.Press  Return  or Stop  to exit the test.
Tray 1
L1=CL L2=CL 
Source L1 L2 P (Pass thru sensor)
Tray 1 Yes Yes Not present
Tray 2*  Yes Yes Yes
Tray 3*  Yes Yes Yes
Tray 4*  Yes Yes Yes
Multipurpose Feeder Yes Not present Not present
* 2000-sheet trays may be in this position. See  “For 2000-sheet trays”. 
						

							
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For 2000-sheet trays
This test can also be used to determine if the 2000-sheet tray sensors are working correctly.
1.Select  Sensor Test  from INPUT TRAY TESTS in the Diagnostics mode. for the tray you want to test.
The following is displayed:
The selected tray is displayed on line 1 < input tray> is either  Tr a y  2, Tr a y  3 , or Tr a y  4 .
2.Manually actuate each tray sensor by moving the flag in and out of the sensor. OP (Open) appears when 
the flag is out of the sensor, or CL (Closed) when the flag is in the sensor.
OUTPUT BIN TESTS
Feed Test
Feed to all Bins (if multiple bins are attached)
Sensor Test
Diverter Test (if 5-Bin mailbox is installed)
Feed Test
Note:   If the “Configure Bins” printer setting is link rather than mailbox, the printer selects its own internal bin 
linking regardless of which output bin is selected for the feed test.
This test verifies that media can be fed to a specific output bin. No information is printed on the media because 
the printhead is not turned on during this test.
To run the Output Bin Feed Test:
1.Select  Feed Test  from OUTPUT BIN TESTS in the Diagnostics mode.
2.Select the output bin you want the paper to exit into. All output bins installed on the printer are shown on 
the feed test menu.
3.Select either  Single (one sheet of media feeds to the selected output bin) or  Continuous (media continues 
feeding to the selected output bin) until  Return or Stop  is pressed.
4.Press  Return  or Stop  to exit the test.
Feed to All Bins
One page is fed to every bin, including the finisher, if available. The test runs continuously until  Return or Stop  
is pressed. <
input tray > EM=OP
NE =OP  LE=OP  SC=OP
EM =trays empty sensor
NE =trays near empty sensor
LE =trays paper level sensor
SC =input trays side cover sensor 
						

							
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Sensor Test
This test verifies if the output bin sensors are working correctly.
The following output sources, if installed, are supported by this test.
Standard Bin
Output Expander
5-Bin Mailbox
To run the Output Bin Sensor Test:
1.Select  Sensor Test  from OUTPUT BIN TESTS in the Diagnostics mode.
2.Select the bin you want to test.
If Standard Bin  is selected the following is displayed.
If Output Expander  is selected the following is displayed:
If 5-Bin Mailbox  is selected the following is displayed:
3.Once the selection is displayed you can manually actuate the sensor you want to test. When the sensor is 
closed CL displays, and when the sensor is open  OP displays.
4.To exit the test press  Return or Stop .
Diverter Test
Note:   This test checks the operation of each mailbox output diverter. Also if more than one 5-Bin mailbox option 
is installed, the test checks all of the diverters installed on the printer.
When the test is selected from OUTPUT BIN TESTS in the Diagnostics mode,  Diverter Test Running is 
displayed.
This is a single test and ends upon completion. Standard Bin
F
=OP
F =Standard Bin Output Bin Full Sensor

P =OP  F=OP  NF=OP
P =Output Expander Pass Thru Sensor.
F =Output Expander Full Sensor
NF =Output Expander Near Full Sensor.

P 1=OP  P2=OP  L=NL
P1 =5-Bin Mailbox first Pass Thru Sensor.
P2 =5-Bin Mailbox second Pass Thru Sensor.
L =5-Bin Mailbox output level sensor where: EM indicates the bin is empty.
NL indicates the bin contains media but the bin is not 
near full nor full.
NF indicates the bin is near full.
FL indicates the bin is full. 
						

							
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FINISHER TESTS
Staple Test
This test verifies the operation of the staple mechanism in the finisher.
To run the Staple Test:
Select Staple Test  from FINISHER TESTS in the Diagnostics menu. The printer feeds eight pieces of media to 
the finisher and accumulates all eight pieces in the accumulator. After the last sheet is accumulated, the pack is 
stapled.
When the test is complete, the printer returns to the original screen.
Finisher Feed Test
This test verifies that media can be fed to the finisher output bin.
To run the Finisher Feed Test, select  Finisher Feed Test from the menu. The printer feeds eight pieces of media 
to the finisher output bin.
Note:   The sheets fed for this test are blank.
This test cannot be canceled or terminated once the test has begun. When the test is complete the printer 
returns to the original screen.
Finisher Sensor Test
This test determines if the finisher sensors are working correctly.
To run this test:
1.Select  Finisher Sensor Test  from FINISHER TESTS in the Diagnostics mode.
If you Select Media 1 from the menu the following is displayed and the sensors polled:
Once the sensors are polled, the following is displayed and the sensors are ready to test:
Once this screen is displayed you can manually actuate each of the sensors. When the sensor is 
closed,  CL is displayed, when the sensor is open  OP is displayed.
Media Path 1
testing............
Media Path 1
S1=OP S2=OP
S1 =Punch Timing Sensor A 
S2 =Punch Timing Sensor B 
						

							
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If you select  Media 2 from the menu the following is displayed and the sensors polled:
Once the sensors are polled the following is displayed and the sensors are ready to test.
Once the screen is displayed you can manually actuate each of the sensors. When the sensor is 
closed,  CL is displayed, when the sensor is open  OP is displayed.
If you select  Media 3 from the menu the following is displayed and the sensors polled:
Once the sensors are polled the following is displayed and the sensors are ready to test:
Once the screen is displayed you can manually actuate the sensor. When the sensor is closed,  CL is 
displayed, when the sensor is open  OP is displayed.
If you select  Media Level  from the menu the following is displayed and the sensors polled:
Once the sensors are polled the following is displayed and the sensors are ready to test:
Once the screen is displayed you can manually actuate the sensor. When the sensor is closed,  CL is 
displayed, when the sensor is open  OP is displayed.
2.To exit the sensor test, press  Return or Stop .
Hole Punch Test
Use this test to verify that media can be fed to the Finisher output bin and hole punched. Letter or A4 size media 
must be used in the source tray for this test. Eight sheets of blank paper are fed and holes punched with a three 
hole or four hole pattern.
To run the test in Diagnostics Mode:
1.Select  Hole Punch Tests  from FINISHER TESTS in the Diagnostics mode.
2.Select 3 Punch Test  or 4 Punch Test .
3.Press Return  after the test is complete to exit the test.
Media Path 2
Testing............
Media Path 2
S3=OP S4=OP
S3 =Inverter Jam Sensor
S4 =Drop Timing Sensor
Media Path 3
Testing..........
Media Path 3
S5 =OP S6=OP
S5 =Exit Timing Sensor
Media Level
Testing...........
Media Level
S1=OP S2=OP
S1 =Tray limit switches
S2 =Paper surface sensor 
						

							
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BASE SENSOR TEST
Use the Base Sensor Test to determine that the sensors located inside the printer are operating correctly. The 
following sensors can be checked using this test:
Input S1
Input S2
In-Line Media 
Fuser exit sensor
K TMC sensor (black)
C TMC sensor (cyan)
M TMC sensor (magenta)
Y TMC sensor (yellow)
See  “Printer sensors” on page 5-3  for locations for these sensors. See  “Cartridge contact assembly pin 
locations (cyan, magenta and yellow)” on page 5-4  or “Cartridge contact assembly pin locations (black)” 
on page 5-5 .
CAUTION:  These sensors are near high voltage terminals to the print cartridge. Use a nonconducting item to 
toggle these switches and not your hand.
To run the Base Sensor Test.
1.Select  Base Sensor Tes t from BASE SENSOR TEST in the Diagnostics mode.
2.Select the sensor to test.
OP for open and  CL for closed are displayed.
3.Manually toggle the sensors by hand to verify that each sensor switches from open to closed.
DEVICE TESTS
Quick Disk Test
This test performs a non-destructive read/write on one block per track on the disk. The test reads one block on 
each track, saves the data, and proceeds to write and read four test patterns to the bytes in the block. If the block 
is good, the saved data is written back to the disk.
To run the Quick Disk Test:
1.Select  Quick Disk Test  from DEVICE TESTS in the Diagnostics mode.
The power indicator  blinks while the test is in progress.
Quick Disk Test/Test Passed  is displayed if the test passes and the power indicator turns on 
solid.
Quick Disk Test/Test Failed  is displayed if the test failed and the power indicator turns on 
solid.
2.Press  Go, Return , or Stop  to retur n to the Device Tests menu.