Read Sony HMD-A200 / HMD-A220 (serv.man3) Service Manual online
HMD-A200/A220
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.
•
HV Protector Circuit Check
Confirm that the voltage between cathode of D521 on D
board and GND is more than 28.5 V DC and Using ex-
ternal DC Power Supply, apply the voltage shown below
between cathode of D521 and GND, and confirm that
the HV HOLD DOWN circuite works. (TV Raster dis-
appears)
Standard voltage : Less than 34 V DC
Check Condition
• Input voltage : 100 – 120 V AC
• Input signal
: White Cross hatch at Max fH
• Beam control : CONT : 255, BRT : 80
•
Beam Current Protector Check
Connect a variable resistor (250 k
Ω
or more) and an am-
meter in series between FBT pin 1 on D board and
GND. Decrease gradually the resistance of the variable
resistor from maximum to minimum, and confirm that
the Beam Current Protector Circuite works (TV Raster
disappears). The current must be within the range shown
below.
• Standard current : Less than 1.50 mA
Check Condition
• Input voltage : 100 – 120 V AC
• Input signal
: White Cross hatch at Max fH
• Beam control : CONT : 255, BRT : 80
•
B+ Voltage Check
Standard voltage : 152
±
5.0 V DC
Check Condition
• Input voltage : 100 – 120 V AC
Note : Use NF power supply or make sure that
distortion factor is 3% or less.
• Input signal
: White Cross hatch at 64.0 kHz
• Beam control : CONT : 255, BRT : 80
*
Confirm one minute later turning on the power.
3-1
Part Replaced (
[
)
RV501
HV ADJ
HV Regulator
Circuit Check
Circuit Check
HV Hold-down
Circuit Check
Circuit Check
Beam Current
Protector Circuit
Check
Protector Circuit
Check
Part Replaced (
]
)
D board IC502, IC503, Q511,
D510, C535, R515,
R554, R559, R560,
R596, RV501,
T501 (FBT)
R554, R559, R560,
R596, RV501,
T501 (FBT)
D board IC501, R598, R599,
T501 (FBT)
D board T501 (FBT)
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