Service manual

SR25-3828VD0171B 3-3 CL - SERVICING
components. After replacement is made, confirm proper
anode voltage using the following procedure.
Measurement of the CRT anode voltage must be performed
using a high impedance-high voltage meter, with no
raster on the screen, and operating at normal horizontal
frequency. 15.75 KHz. (NTSC signal).
After discharging the CRT, connect a high impedance-
high voltage meter to the CRT anode. Turn the television
"on" and confirm a good signal is being displayed. Reduce
Brightness and Contrast setting until the procedure is
well extinguished.
Observe the anode voltage on the meter reading and
compare with the table below for the proper CRT screen
size. If the voltage reading is higher than the maximum,
verify circuit component values and proper operation.
CRT Screen Size
Nominal Anode Voltage
(KV)
Max. Shutdown Voltage
(KV)
19" 26 ± 1.0 32
20” 26 ± 1.0 32
24"/25” 28 ± 1.0 34
27” 28 ± 1.0 34
32” 30 ± 1.0 36
CRT anode Voltage
COMPONENTS WITH ANY INFLUENCE IN HV INCREASE
CX3216 RX3015
CX3210 RX3013
CX3212 ZDX3004
CX3252 RX3704
CX3256 RX3703
RX3022 RX3705
COMPONENTS WITH ANY INFLUENCE IN HV INCREASE
Fly-Back Transformer
Deflection Yoke
HV SHUTDOWN PROCEDURE
1 After discharging the CRT, connect a high
impedance-high voltage meter to the CRT
anode.
2 Access Video Menu and adjust the brightness
and contrast controls for minimum screen
luminance (beam current to 0mA).
SERVICE ADJUSTMENTS (continued)
3 Wait until the Video Menu or display appears.
4 Connect a variable Resistor (1M ohm) in parallel
with RX3703, and decrease slowly the resistance
value until shutdown occurs.
5 Measure high voltage shutdown.