Hitachi 46W500 Training page 62

DP-3X IH01 HIGH VOLTAGE DRIVER IC WAVEFORM AND VOLTAGES
IH01 NORMAL OPERATION:
Pin 1 = 6.80V with Color Bar,
Varies with Brightness levels.
Pin 2 = 11.72V
Pin 3 = 0.59V
Pin 4 = 2.47V
Pin 5 = 1.60V
Pin 6 = 10.58V
Pin 7 = 0.0V
Pin 8 = 0.0V
Pin 9 = 4.90V
Pin 10 = 0.03V
Pin 11 = 0.03V
Pin 12 = 4.90V
Pin 13 = 0.05V
Pin 14 = 2.02V
Pin 15 = 4.96V
Pin 16 = 0.0V
IH01 NOT RUNNING:
Pin 1 = 12.28V
Pin 2 = 11.86V
Pin 3 = 3.96V
Pin 4 = 3.5V
Pin 5 = 1.089V
Pin 6 = 0.021V
Pin 7 = 0.0V
Pin 8 = 0.0V
Pin 9 = 0.019V
Pin 10 = 0.038V
Pin 11 = 0.038V
Pin 12 = 4.90V
Pin 13 = 0.05V
Pin 14 = 4.59V
Pin 15 = 4.96V
Pin 16 = 0.0V
9 10
+
-
UVP OVP POUT
8 7
Pin 1
Pin 3
Pin 4
NOT RUNNING EXPLANATION:
This situation can happen and possibly lead the Service Technician
off on the wrong path.
Take a quick look at the voltages for pin 3 and 14. This is the key.
These two pins tie back to the Horz. and Vert. Sweep Loss Detec-
tion Circuit.
(See page 05-05 for the Sweep Loss Detection Circuit Diagram).
If the Sweep Loss circuit is activated, it outputs a high from QN02.
This high is used to shut off the CRT to prevent CRT burn, How-
ever, the Collector of QN02 is also routed to these two pins through
diodes DN09 to pin 14 and DN10 to pin 3.
When QN02 goes high, it drives pin 3 and 14 high which turns off
the internal oscillator of IH01 via pin 3. This action stops Horizontal
Drive to the High Voltage circuit. This action causes pin 1 to satu-
rate and it goes High.
Note that pin 14 is tied to an internal op-amp (-) leg. This cause the
output to stop. So no Horizontal Drive is allowed to pass to the out-
put amp. connected to pin 1.
11 12 13 14
AGC GEN
6 5 4 3
12V P/P 33.75Khz
4.5V P/P 33.75Khz
3V P/P 33.75Khz
15 16
Gnd
REF
-
-
+
UVLO
2 1
PAGE 05-04