Table l-l. Al5 Controller Self Test Fail Indicators
Al5 LED
On
DSl
DS2
DS3
DS4
DS5
DS6
DS7
DSB
DS9*
DSlO*
DSll
DS12
DS13
DS14
DS15t
Affected
Circuitry
Processor
Top Box Address
Bottom Box Address
I/O, Data Bus
RAM
RAM
RAM
RAM
ROM
ROM
ROM
ROM
ROM
ROM
RAM
Probable Failure
Al5U26
Use oscilloscope to isolate failure.
Use oscilloscope to isolate failure
Use oscilloscope to isolate failure.
A15U18
A15U15
A15U17
A15U14
A15U19
A15U16
A15U39
A15U37
A15U40
A15U38
Power Supply (VRAM)
k
A15U16 and A15U19 are loaded when 128K ROMs (set of 6) are installed.
A15U16 and A15U19 are not loaded when 256K ROMs (set of 4) are used.
. DS15 should normally stay on. If DS15 is not on, suspect the
power supply that supplies VRAM.
1
Al5 7