Sony GDM-F500T9 User Manual
GDM-F500/F500T9
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.
d) Beam Current Protector Circuit Check-1
(Hardware)
Connect a variable resistor (20 k
Ω
or more) and an am-
meter in series between pin !¡ of T901 (FBT) and –15
V line. Decrease gradually the resistance of the vari-
able resistor from maximum to minimum, and confirm
that the Beam Current Protector Circuit works and TV
Raster disappears. The current must be within the
range shown below.
Check Condition
•
Input signal
: White Cross Hatch at 120.7 kHz
•
Beam control : BRT = 0, CONT
= 0
•
Standard
: 1.49 mA
e) Beam Current Protector Circuit Check-2
(Software)
1) Short between + of C937 and GND.
2) Connect a variable resistor (20 k
Ω
or more) and an
ammeter in series between pin !¡ of T901 (FBT) and
–15 V line. Decrease gradually the resistance of the
variable resistor from maximum to minimum, and
confirm that the Beam Current Protector Circuit
works and TV Raster disappears. The current must
be within the range shown below.
Check Condition
•
Input signal
: White Cross Hatch at 120.7 kHz
•
Beam control : BRT = 0, CONT
= 0
•
Standard
: 1.59 mA
*
Confirm one minute later turning on the power.
a) B+ Voltage Check
Check Condition
•
Input voltage : 100 ~ 240 VAC
•
Input signal
: White Cross Hatch at 120.7 kHz
•
Beam control : BRT and CONT
→
MAX
•
Standard
: 200 ± 3.0 V DC
b) HV Regulator Circuit Check
1) Confirm that the voltage of the + side of C910 on G
board is within the voltage range shown below.
Standard: 8.940 ~ 9.065 V DC
c) HV Protector Circuit Check
1) Confirm that the voltage between cathode of D913
on G board and GND is more than 26.5 V DC.
2) Confirm that the HV protector circuit works and TV
Raster disappears when apply the voltage as shown
below between cathode of D913 and GND using an
external DC power supply.
Check Condition
•
Input voltage : 100 ~ 240 VAC
•
Input signal : White Cross Hatch at 120.7 kHz
•
Beam control : BRT and CONT
→
MIN
•
Standard
: Less than 34.20 V DC
SECTION 3
SAFETY RELATED ADJUSTMENT
Part Replaced (
])
G Board IC901, T901
•
Mounted G board
G Board Q907,
Q908,
D913,
D916,
C923,
R920,
R927,
R952,
T901
•
Mounted G board
D Board R011,
R1068
•
Mounted D board
G Board IC901, IC902, Q907,
Q908,
D902,
D918,
D919,
R923,
R928,
R933,
R934,
R942,
R944,
R945,
R947,
R948,
R951,
R952,
T901
•
Mounted G board
HV Regulator
Circuit Check
Circuit Check
HV Protector
Circuit Check
Circuit Check
Beam Current
Protector Circuit
Check
Protector Circuit
Check
3-1