Samsung ML-7000P Service Manual page 18

5-5-2. Troubleshooting Table of Video Controller Board
NO. Error Type
The backlight
1 of LCD is not
lit up
It doesn't
displayed
2
characters on
LCD
3 White copy
4 DRAM Error
5 EEPROM
6 ROM Error
7 Engine Error
Parallel
8 Interface
Error
General desc-
riptions of
9
troubleshooting
Download Service Manual And Resetter Printer at http://printer1.blogspot.com
Ckeck List
Power cord connection
Vcc voltage(nominal is +5V) level
Vcc voltage should be in the range between+4.38-+5.2V
Short Between Vcc and GND
Mutual connection of engine, key panel to LCD
panel's connected cable(10pin), video board to key
panel's connected cable(20pin) and engine interface
cable(28pin)
The pin of connector is straigh.
Mutual connection of panel cabel(10pin)
video board to key panel's connected cable(20pin)
Any component damage on a video controller board.
Any foreign conductive chips of solder or material
is on the video controller board or is laid between
IC pins after power off.
Reset Error:Reset signal is normal high during operation
ß÷
System source clock is a 50
Check point : U16(FS741)'s pin No.6,
The output clock of QP17000 is a 25
The input clock of CPU(U26) and U24 is a 25ß÷ .
The video data colck source is a 62.7639ß÷ at OSc2
The input clock of U31 is a 62.76397ß÷ .
The output clock of U31 is a 16ß÷ .
The input clock of U2's pin No.125 is a 16ß÷ .
°· C heck the normal operation of HSYNC* and PSYNC*
°· C heck the DRAM address signals.(pin No. 17-20, 23-28 : U20, U290)
°· C heck the DRAM data signals. (pin No. 2-5. 7-10. 33-36. 38-41 : U20, U29)
°· C heck the EEPROM clock signal. (pin No. 2 : U1)
°· C heck the EEPROM data signals. (pin No. 3,4 : U1)
°· C heck the ROM chip select signals and read signal (pin No. 12,14)
°· C Heck the ROM data signals. (pin No. 15-22, 24-31 : U25, U27, U30, U32)
°· R efer to the section of Engine troubleshooting
°· C Heck the operation of printer driver.
°· C heck the printer cable(bidirectional cable)
°· P lease refer to the user's manual.
°· I f you can't fix the trouble of video controller
board, replace the video board by the verified
board.
Repair
Connect the power cord
Refer to the section of
Engine troubleshooting
Repair board
Connect the cable to
connector
Confirm the connection
of connector
Repair or replace it
with appropriate tools.
If uanable to do this,
replace video board.
Remove any foreign
conductive chips on the
video controller board.
Replace the FS741
ß÷ .
Replace the board
Replace the board
Active low impulse
Refer to USER's manual
Replace the printer
cable
Replace the board