Table of Contents
Advertisement
PVM-20M7MDE
3·6. P Board
3-9. Trouble Detection Circuit
The P board has the horiwntal output circuit, vertical output circuit
and the vertical static convergence circuit (V. STA). IC901
(JDA8172) is the V. output IC. Because the positive power supply
(+ ISV) of the V. output circuit is generated from the 3rd order
output of the
FBT (T3003),
the high voltage circuit stops
if
the V.
output circuit is stopped. Q9I l is H. output transistor. The
horizontal PIN distortion c01rection is controlled by +B switch of
Q903.
If
Q9l I becomes defective and shorted, Q903 and R916
could be broken at the same time. IC904 (2/2) is the V. STA
circuiL Output of the V. STA is supplied to the neck twist coil
(NTC) which
is located at the CRT neck.
3~7.
c,
G, H and
a
Boards
The C board is the video output board located at the CRT neck.
The G board is power supply board. If any abnonnality occurs in
itsload,R616,R617,R619,R620,R629,
F601 orF602couldbe
opened. The H board is the front control board. The Q board is
the input/output terminal board on the rear of the monitor. IC403
is the RS-232C interface which converts the RS-232C signal level
tothe+5Vlevel.
3-8. Power Saving Circuit
In this moni1or, the CPU (IC2003) monitors pin@
(V.
sync) and
pin® (2H. SYNC), and enter the power saving operation if"NO
SYNC'' is detected for the period of 10 minutes or 30 minutes. IT
the monitor enters the power saving operation, Pin (j) (APO!) of
the CPU is set to H which stops the HV. out drive pulse through
Q3015 of the A board page 4which turns off the high voltage
circuit. Then, pin@ (AP02) is set
to
H which stops the horizontal
drive pulse (HD) through IC2007 (415), and also stops the vertical
reference pulse (V. DEFI.) through IC2012 which stops the V.
'"'
-21-
If this monitor has a trouble, the trouble detection circuit is
included to help locating the cause of trouble. The trouble
detection is performed by the pin@topin@ of the CPU (IC2003).
The troubles which are not input to the CPU cannot be detected.
Result of trouble detection is displayed by the flashing of the
POWER SAVING indicator.
Number of flashing and main cause of trouble
I time·······
H.output(PboardQ9ll)
is stopped.
2times ·•····
V.output(PboardIC901)isstopped.
3 times • · · · · · HY protector is operating.
4 times • • • • • • IK protector is operation or excess current of
+B power supply of HY output
5
times
· Fan is stopped, or HV output circuit is stopped
resultinginstopoffan.
6 times
IIC bus communication error
?times······
Othererrors
In the case if no picture Is output and the POWER SAVING
l_~DJCAJQB._do.es_n.ot_flash.
H the POWER SAVING indicator does not turn on. +12V power
supply could be defective. Press the UNDER SCAN switch and
confirm that the UNDER SCAN indicator turns on. Ifit
does
not
tum on, +5V power supply might be defective, or fuses (F601,
F602) are open. In other word, trouble in +12V power line can be
detected from the POWER indicator while +5V power line can
be detected from the UNDER SCAN indicator. If both of them
are defective, the entire power supply unit could be d~fective
(blown fuse, no AC input. defective SRT, and others).
Advertisement
Table of Contents
