Casio CTK-4000 Service Manual & Parts List page 13

2. AC adaptor check
 Press "3" button.
Make sure that a value "XXX" shown in the illustration is in
the range of 000 to 3FF.
 Press "3" button.
Make sure that a value "XXX" shown in the illustration is in
the range of 000 to 1FF.
 Press "0" to end the AC adaptor Check.
3. Memory check
 Press "5" button. (ROM check)
 Press "1" button.
* Check for "OK" message and sound signal.
 Press "0" to end the ROM Check.
 Press "6" button. (RAM check)
 Press "1" button.
* Check for "OK" message and sound signal.
 Press "0" to end the RAM Check.
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3:AD1XXX
000 to 3FF
3:AD3XXX
000 to 1FF
TEST 1-9
5:ROM
OK
TEST 1-9
6:MEM
OK
TEST 1-9