Safety Related Adjustment - Sony GDM-90W01T5 Service Manual

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.
HV Regulator GB board
Circuit Check
HV Hold-Down G board
Circuit Check
Beam Current G board
Protector#1
Circuit Check
GB board
Beam Current G board
Protector#2
Circuit Check
Voltage of 3rd G board
winding of FBT
Check Condition
Input voltage : 100~120 V AC
Input signal : White dots or Cross Hatch
: BRT and CONT → Minimum
Controls
B+ voltage : 193~201 V DC
SECTION 3

SAFETY RELATED ADJUSTMENT

Part Replaced (])
IC4202
• Mounted GB board
D4220
• Mounted G board
• Mounted GB board
D4204,D4206,D4220,
R4211,R4212,R4216,
R4219
• Mounted G board
IC4202
• Mounted GB board
R4222, R4223
• Mounted G board
• Mounted GB board
T4202(FBT)
• Mounted G board
– 17 –
a) HV Regulator Circuit Check
1) Confirm that the voltage of the pin !. of IC4202
on GB board is within the voltage range shown be-
low.
Standard: 9.00±0.10 V DC
b) HV Hold-Down Circuit Check
1) Using an external DC power supply, apply the
voltage shown below between cathode of D4220 on
G board and ground, and confirm that the HV Hold-
Down circuit works. (TV Raster disappears)
Check Condition: Less than 33.8
c) Beam Current Protector#1 Circuit Check
1) Record the initial regulation value of ABL-
SHUTDOWN and using a PC computer, input the
"255" for maximum value of resistor.
2) Connect to the Constant Current Jig (A) between pin
!] of T4202 (FBT) on G board and ground, and
confirm that the Beam Current Protector Circuit
works. (TV Raster disappears)
Check Condition: Less than 1.55 mA
d) Beam Current Protector#2 Circuit Check
Input the initial regulation value of ABL-SHUTDOWN
that was recorded c)-1).
1) Shorted between pin !] of IC4202 on GB board and
ground.
2) Connect to the Constant Current Jig (A) between pin
!] of T4202 (FBT) on G board and ground, and
confirm that the Beam Current Protector Circuit
works. (TV Raster disappears)
Check Condition: Less than 1.72 mA
e) Voltage of 3rd winding of FBT
1) Confirm that the voltage of the cathode of D4220 on
G board is within the voltage range shown below.
Satndard: More than 28.0 V DC
GDM-90W01T5
+0.0
V DC
–0.1