IBM 19K1902 Service Manual page 10

CHECK
U5
(5V)?
YES
CHECK
VR1?
YES
TROUBLE IN R3, R6, R9
CHECK
U3 PIN 4, 9
AUDIO IN?
YES
CHECK
U3 OUTPUT
PIN 14, 17 ?
YES
TROUBLE IN SPEAKER
2. NO VOLUME CONTROL
NO
NO
NO
3. AUDIO NO OUTPUT
NO
CHECK
J4 AND PC?
NO
CHECK
U3 PIN 11, 12
(0V) ?
- 10 -
TROUBLE IN U5
TROUBLE IN VR1
TROUBLE IN U3
YES
TROUBLE
IN U3
YES
TROUBLE
IN U3