Section 2: Safety Related Adjustments; Hv Regulator Check; Hv Protector Circuit Check; Beam Protector Check (Software Logic) - Sony Trinitron HMD-A240R 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. Confirm that the voltage is within the voltage range shown below:
Standard voltage: 26.0 +0.3, -0.5 kV
6. When replacing components identified 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 specification. 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 specification, put the RV
cover on RV501 as shown below and apply sufficient 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. Confirm that the voltage between cathode of D517 and GND is
more than 27.0 VDC.
2. Using an external DC Power supply, apply the voltage shown
below between cathode of D517 on D Board and GND, and confirm
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 confirm 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 distortion factor is
3% or less.
4. Confirm 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-A240R
11