GDM-200PS/200PST/200PST9
SECTION 3
SAFETY RELATED ADJUSTMENT
Part Replaced (
[
)
RV901
HV ADJ
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.
•
Beam Current Protector Circuite Check
(1) Hardware logic circuit
•
Turn the POWER SW on, and check that the RASTER
fades in.
•
Connect a variable resistor (20 k
Ω
or more) and an
ammeter in series between FBT pin
!]
and – 15 V line
(– side of C637). Decrease gradually the resistance of
the variable resistor from maximum to minimum, and
confirm that the Beam Current Protector Circuite
works (TV Rester disappears). The current must be
within the range shown below.
Standard current: Less than 1.09 mA
(2) Software logic circuit
•
Turn the POWER SW on, and check that the RASTER
fades in.
•
Short b of C639 and GND.
•
Connect a variable resistor (20 k
Ω
or more) and an
ammeter in series between FBT pin
!]
and – 15 V line
(– side of C637). Decrease gradually the resistance of
the variable resistor form 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 1.14 mA
HV Regulator
Circuit
HV HOLD
DOWN Circuit
Beam Current
Protector Circuit
Part Replaced (
]
)
D board IC901, R903, R922,
T901
• Mounted D board
D board D913, D916, C923,
R920, R927, T901
• Mounted D board
D board IC901, D902, D918,
D919, R923, R928,
R932, R933, R934,
R942, R944, R945,
R947, R948, R951,
T901
• Mounted D board
*
Confirm one minute later turning on the power.
•
HV Protector Circuit Check
(1) Confirm that the voltage between cathode of D913
and GND is more than 17.5 V DC.
(2) Using external DC Power Supply, apply the voltage
shown below between cathode of D913 and GND,
and confirm that the HV HOLD DOWN circuite
works. (TV Rester disappears)
Standard voltage: Less than 23.40 V DC
3-1
