Compaq MV7540, Service Manual

Page: 20 / 49

HP MV7540
20
6-4 H-Size Fails To Be Adjusted
6-5 Bad Focus
The picture is too large and H-size can’t be adjusted
The picture is too small and H-size can’t be adjusted
Cut the collector of Q406 and look if the picture becomes
smaller, then check the voltage of circuit is half of B+.
Check if the voltage of H-size control
transistor is half of B+.
Connect collector of Q406 and cut base of Q406, then
look if the picture becomes small.
Replace Q406
Replace D406
Check the voltages concerned
with collector of Q406 as D406,
D407, L405, C422.
Cut pin24 of IC401 and check if the voltage is between 3.0 and 2.3v
when adjust H-size function
Replace IC401
Check the components betweenpin24 of IC401and base of Q406 as
Q406, R434, R490, Q404, C421, R440, Q405 etc
Check the voltage of base of Q406 is between 0.5 and 1.1V when
adjust the H-size functional key.
NO
NO
NO
NO
NO
YES
YES
YES
YES
Readjust FOCUS control
Check focus control unit, CRT
socket and CRT.
NO