IBM 5150 Hardware Maintenance Manual page 94

Press the
[9
key and listen for two "beeps." The voltages
listed in the table below should be present on pins 8 and 9 of
the 9 pin connector; at the phono-jack connector, the voltage
should be between 1.0 and 1.5 volts DC. Measure the voltages
present at pins 8 and 9 of the 9 pin connector and the voltage
between the center and outer edge of the phono-jack.
Pin Volts, DC
8 0.0-0.7
9 0.0-0.4
Phono 1.0-1.5
o
0
•
o
WERE YOU ABLE TO READ THE PROPER VOLTAGES ON
PINS 8 AND 9 AND AT THE PHONO-JACK CONNECTOR?
NO
Replace your Color/Graphics Monitor Adapter. See
Section 3, "Removal/Replacement."
YES
500-23