Read Sony GDM-F400 / GDM-F400T9 Service Manual online
GDM-F400/F400T9
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.
*
Confirm one minute later turning on the power.
a) HV Protector Circuit Check
1) Confirm that the voltage between cathode of D913
on G board and GND is more than 25.5 V DC.
2) Confirm that the HV protector circuit works and TV
Raster disappears when apply the voltage less than
34.2 V DC between cathode of D913 and GND using
an external DC power supply.
SECTION 3
SAFETY RELATED ADJUSTMENT
Part Replaced (
])
D Board T901(FBT), IC901,
R903, R922, RV901
•
Mounted D board
D Board T901(FBT), R927,
R920, C923, D913,
D916, R935, R936
D916, R935, R936
•
Mounted D board
D Board R933, R932, R934,
R923, R928, R939,
R918, R053, IC901,
D918, D901, D902,
T901(FBT)
R918, R053, IC901,
D918, D901, D902,
T901(FBT)
•
Mounted D board
HV Regulator
Circuit Check
Circuit Check
HV Protector
Circuit Check
Circuit Check
Beam Current
Protector Circuit
Check
Protector Circuit
Check
3-1
Part Replaced (
[)
RV901
HV ADJ
b) Beam Current Protector Circuit Check-1
(Hardware)
Apply 4.7 V DC to the connection point of R932 and
R933. Connect constant current source to the FBT !¡
pin (–) on the D board and to the GND, then confirm
that when 2.0 mA is flown, the beam protector circuit
operates and high voltage value drops over 1.0 kV.
c) Beam Current Protector Circuit Check-2
(Software)
Connect constant current source to the FBT !¡ pin (–)
on the D board and to the GND, then confirm that when
1.7 mA is flown, the beam protector circuit operates
and IIV value (CRT anode voltage) is below 1.0 k
VDC.
Or, confirm that the raster disappears.
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