Safety Related Adjustments; Hv Regulator Check; Hv Protector Circuit Check; Beam Protector Check (Software Logic) - Sony TRINITRON HMD-A240 Service Manual

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.
HV ADJ
D Board T501, IC501, RV501, R540,
HV Regulator
Circuit
D Board T501, R510, R543, R547, R549,
HV HOLD
DOWN Circuit
D Board T501, R545, R546, R548, R550,
Beam Current
Protector Circuit
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. ConÞ rm that the voltage is within the voltage range shown below:
Standard voltage: 26.0 +0.3, -0.5 kV
6. When replacing components identiÞ 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 speciÞ 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 speciÞ cation, put the RV
cover on RV501 as shown below and apply sufÞ cient amount of RTV
around RV501.
SECTION 2: SAFETY RELATED ADJUSTMENTS
Part Replaced ( )
RV501
Part Replaced ( )
R541, R542, R544, R564, R567,
R568, C532, C534, C539, C553,
C554, C555, C556, C558, C561
R552, R595, D515, D517, C540,
C542, C544, IC607, IC901, C951
R596, R934, C535, C541, IC605,
IC607, IC901
RV501

2-2. HV PROTECTOR CIRCUIT CHECK

1. ConÞ 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 conÞ rm that
the HV Hold-Down circuit works (Raster disappears). Apply DC
Voltage: Less than 35.9 VDC.
Check Condition
• Input voltage:
• Input signal:
• Controls:
• B+ Voltage:
2-3. BEAM PROTECTOR CHECK
(SOFTWARE LOGIC)
1. Using an external current source, apply < 1.55mA between pin
of FBT (T501) and GND, and conÞ rm that the raster fades out.
Check Condition
• Input voltage:
• Input signal :
• Controls:

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. ConÞ rm that the voltage is within the range shown below:
Standard voltage: 179 ± 3.0 VDC
— 10 —
120 ± 2 VAC
(fH =69 kHz), White Cross Hatch
CONT (max) & BRT (center)
179 ± 3.0 VDC
120 ± 2 VAC
(fH = 69 kHz), White Cross Hatch
CONT (max) & BRT (center)
HMD-A240
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