Protection Circuit (Hold-Down Circuit) Check - Sony TRINITRON PVM-14N5A Service Manual

4-2. PROTECTION CIRCUIT (HOLD-
DOWN CIRCUIT) CHECK
Note: Besure to use the NF power supply. If not, use
an ordinary power supply of its distortion
factor is 3% or less.
1. Protection Circuit Normal Operation Check
Input voltage:
Input signal:
Controls:
Specification:
120 + 3 Vac
Black
BRIGHTNESS => Minimum
CONTRAST ™ Minimum
Confirm that the voltage at Cathode of
D103 on the A board and ground is
greater than 99.0 Vdc.
2. Protection Circuit Operation Check (1)
Input voltage:
Input signal:
Controls:
Specification:
130 Vac
Black
14-inch: IABL = 40 +20 pA
20-inch: IABL = 120 +20 pA
Apply following voltage to Cathode of
D103 on the A board from the external
DC power supply and make sure that the
hold-down circuit doesn't work.
14-inch: 119.6 18.4 Vac
20-inch: 145.2 *8.4Vac
3. Protection Circuit Operation Check (2)
Input voltage:
Input signal:
Controls:
Specification:
4-2
130 Vac
Black
14-inch: IABL = 40 £20 pA
20-inch: I[ABL = 120 +20 pA
Apply following voltage to Cathode of
D103 on the A board from the external
DC power supply and make sure that the
hold-down circuit works.
14-inch: 128.4 *8.4 Vac
20-inch: 156.6 *8.4Vac
SITAtyassis