Part Replaced ( )
HV ADJ
RV501
Part Replaced ( )
D Board
T501, IC501, RV501, R540,
R541, R542, R544, R564, R567,
R568, C532, C534, C539, C553,
C554, C555, C556, C558, C561
HV Regulator
Circuit
D Board
T501, R510, R543, R547, R549,
R552, R595, D515, D517, C540,
C542, C544, IC607, IC901, C951
HV HOLD
DOWN Circuit
D Board
T501, R545, R546, R548, R550,
R596, R934, C535, C541, IC605,
IC607, IC901
Beam Current
Protector Circuit
— 10 —
HMD-A240
2-2. HV PROTECTOR CIRCUIT CHECK
1. Con
Þ
rm that the voltage between cathode of D517 and GND is
more than 27.0 VDC.
2. Using an external DC Power supply, apply the volt age shown below
between cathode of D517 on D Board and GND, and con
Þ
rm that
the HV Hold-Down circuit works (Raster disappears). Apply DC
Voltage: Less than 35.9 VDC.
Check Condition
• Input voltage: 120 ± 2 VAC
• Input signal: (fH =69 kHz), White Cross Hatch
• Controls: CONT (max) & BRT (center)
• B+ Voltage: 179 ± 3.0 VDC
2-3. BEAM PROTECTOR CHECK
(SOFTWARE LOGIC)
1. Using an external current source, apply < 1.55mA between pin
11
of FBT (T501) and GND, and con
Þ
rm that the raster fades out.
Check Condition
• Input voltage: 120 ± 2 VAC
• Input signal : (fH = 69 kHz), White Cross Hatch
• Controls: CONT (max) & BRT (center)
2-4. B+ VOLTAGE CHECK
1. Input white cross hatch (fH = 69 kHz) signal.
2. CONT (max) & BRT (center).
3. Input voltage: 110 ± 10 VAC.
Note
: Use NF power supply or make sure that dis tortion factor is
3% or less.
4. Con
Þ
rm that the voltage is within the range shown below:
Standard voltage: 179 ± 3.0 VDC
SECTION 2: SAFETY RELATED ADJUSTMENTS
When replacing parts shown in the table below, the following
operational checks must be performed as a safety precaution
against X-ray emissions from the unit.
Allow the unit to warm up for one minute prior to checking the
following conditions.
2-1. HV REGULATOR CHECK
1. Input white cross hatch signal (fH = 80 kHz).
2. CONT maximum and BRT center.
3. Cut off Screen VR (G2).
4. Input voltage: 120 ± 2 VAC.
5. Con
Þ
rm that the voltage is within the voltage range shown below:
Standard voltage: 26.0 +0.3, -0.5 kV
6. When replacing components identi
Þ
ed by
Y
, make sure to recheck
the High Voltage.
7. Verify the High Voltage as shown above (26.0 +0.3, -0.5 kV) is
within speci
Þ
cation. If not, set H. SIZE data at minimum (-127)
and then adjust RV501 on D Board (Adjustment target = 26.0 ±
0.2 kV).
8. After adjusting the High Voltage within speci
Þ
cation, put the RV
cover on RV501 as shown below and apply suf
Þ
cient amount of RTV
around RV501.
RV501
104
