Dram Test Mode - Brother HL-2400C Service Manual

2.4

DRAM Test Mode

This mode tests the memory and optional SIMMs installed on the main (video controller)
PCB.
<Procedure>
1) To start the test program:
While holding down the
be displayed. Press the Continue button to start the DRAM check.
2) The LCD will display "START DRAM TEST", and the Data LED blinks.
3) On satisfactory completion of all the RAM tests, the LCD will display: "DRAM OK!!",
and the Alarm LED is on.
4) If any DRAM error has occurred, the LCD will display a fail message as follows;
5) Enter the hidden menu mode as follows to confirm the current memory map;
i) Press the Form Feed, Mode and Continue buttons at the same time in the off-
line status.
ii) The LCD will display "HIDDEN PANEL"
iii) Select the "DRAM ADDRESS" menu using the scroll buttons.
iv) Whenever the Set button is pressed, the LCD will display the DRAM error
address on the main PCB, Slot 1, Slot 2, and Slot 3 in turn.
6) If a SIMM DRAM has an error, replace the SIMM corresponding to the above
memory map information.
If the DRAM on the main PCB has an error, replace referring to the table below;
Lower order address
(where an error occurs)
*A: If the upper digit of the data is wrong.
*B: If the lower digit of the data is wrong.
Note:
There may be a case where the above sequence does not work correctly due to
complete RAM failure, or in faulty assembly such as a solder bridge or ineffective
soldering etc.
"PRINT CHECK" may be displayed when exiting from the Test mode. It will disappear
in 20 or 30 seconds, displaying "READY" on the LCD. It is not a fault.
button, turn on the power. "DRAM CHECK START" will
RAM Address
0, 4, 8, C
1, 5, 9, D
2, 6, A, E
3, 7, B, F
WRITE data
DRAM chip to be replaced
*A
#3
#9
#4
#14
V-8
READ data
*B
#5
#16
#7
#20