Pdos For Ram And Cpu Check - Epson LQ 1050 - B/W Dot-matrix Printer Technical Manual

5.2.6 PDOS for RAM and CPU Check

If you want to run only the RAM check or CPU check, you do not need the host computer.
Install the diagnostics ROM in the printer at location IC4A.
LOCATION
F X - 8 5 0 / 1 0 5 0
PRINTER DIAGNOSTICS
ROM
(1) Turn the power on.
(2) Check to see if the ONLINE LED light is on or off.
(3) Check to see if any LEDs are blinking.
POWER ON
POWER\ READY/PO/ONLINE LEDs ON -~
ALL LEDS TURNS OFF
+
ONLINE LED ON
(YES) FINISH IC7C INITIALIZE
I
PAPER OUT LED ON
(YES) FINISH IC3A INITIALIZE
READY LED ON
ONLINE LED BLINKS
(NO)
PAPER OUT LED BLINKS
(NO)
I
READY LED BRINKS
(NO)
BUZZER BEEPS
(YES)
READ DIP SWITCHES
(Perform Function. IF DIP SW1 =OOH then stop)
NOTE: Check does not require connection to a host
computer.
Figure 5-7. RAM and CPU Check
(NO)
CHECK +5V LINE
(NO)
CPU DOES NOT WORK.
(NO)
REPLACE IC7A.
(NO)
REPLACE IC3A.
(NO)
REPLACE IC4B.
(YES)
REPLACE IC5A (RAM ERROR)
(YES)
REPLACE IC6A (RAM ERROR)
(YES)
REPLACE IC4B(RAM ERROR)
(NO)
REPLACE IC7A
5-7