GDM-4011P
SECTION 3
SAFETY RELATED ADJUSTMENT
When replacing or repairing the shown below table, the
following operational checks must be performed as a
safety precaution against X-rays emissions from the unit.
a) HV Regulator Circuit Check
1) Confirm that the voltage of the pin
2
of CN901 on D
board is within the voltage range shown below.
Standard: 9.00±0.068 VDC
b) HV Protector Circuit Check
1) Confirm that the HV protector circuit works and TV
Raster disappears when apply the voltage as shown
below between pin
3
of CN901 on D board and
GND using an external DC power supply.
Check Condition: Less than 31.30 VDC
c) Beam Current Protector Circuit Check-1
1) Measure HV voltage and record that value.
2) Shorted between pin
1
and pin
4
of CN901 on D
board.
3) Connect to the Constant Current Jig (A) between pin
1
of CN901 on D board and GND, confirm that the
Beam Current Protector Circuit works and HV go
down more than 1.50 kV from the value of (1).
Check Condition: 1.50 mA
d) Beam Current Protector Circuit Check-2
1) Connect to the Constant Current Jig (B) between pin
1
of CN901 on D board and GND, confirm that the
Beam Current Protector Circuit works and TV Raster
disappears.
Check Condition: 1.57 mA
e) Voltage of 3rd winding of FBT
1) Confirm that the voltage of pin
3
of CN901 on D
board is within the voltage range shown below.
Standard: more than 23.30 VDC
Check Condition
Input voltage : 100~120 VAC
Input signal : White Cross Hatch at 96 kHz
Beam control : BRT and CONT
→
Minimum
B+ voltage
: 177~183 VDC
HV Regulator
Circuit Check
HV Protector
Circuit Check
Beam Current
Protector Circuit
Check
Part Replaced (
]
)
D Board IC901, T902
• Mounted D board
D Board Q590, Q591, D916,
D935, C924, R597,
R598, R940, R980,
T902
• Mounted D board
G Board PH680, Q680, Q683,
D680, R680, R686,
R687, R688, R689
• Mounted G board
D Board IC901, D904, D907,
D908, R011, R908,
R909, R921, R925,
R926, R929, R930,
T902
• Mounted D board
3-1
