Disclaimer: This information is provided “as is” without warranty of any kind
either expressed or implied, including, but not limited to, the implied
warranties of merchantability and fitness for a particular purpose.
REV 5-1
SERVICE BULLETIN
PRODUCT: Computer Monitor
BULLETIN: MON 97-001
MODEL: CQB4147
SUBJECT: Reduce Q404 Failure Rate Causing No Raster
BACKGROUND: Q404 fails when the monitor changes from the DPMS
Suspend mode back to Normal operation. Q415 is designed, in the circuit, to cut
off horizontal drive to the base of Q404. This is achieved by turning Q415 on in
the Suspend mode. In normal operation, Q415 is turned off. There is a delay in
turning Q415 off by approximately 15 ms. This will cause an abnormal pulse at
the base of Q404, causing damage to the transistor.
SOLUTION: The base current limiting resistance to Q415 has been changed by
decreasing the values of R200 and R461.
PARTS LIST:
ORIGINAL
NEW
Location No.
Part No.
Description
Part No.
Description
R200
2001-000056
R-CF 4.7K, 1/6W
2001-000043
R-CF 1K, 1/6W
R461
2001-000056
R-CF 4.7K, 1/6W
2001-000029
R-CF 100 OHM, 1/6W
