Circuit Checks - Toshiba 40PW03G Service Manual

HIGH VOLTAGE CHECK
CAUTION: There is no HIGH VOLTAGE ADJUSTMENT on this chassis. Checking should be done following the steps below.
1. Connect an accurate high voltage meter to the anode of the picture tube.
2. Turn on the receiver. Set the BRIGHTNESS and CONTRAST to minimum (zero beam current).
3. High voltage must be measured below (B) kV.
Refer to table-1 for high voltage (B).
(See SETTING & ADJUSTING DATA on page 34)
4. Vary the BRIGHTNESS to both extremes to be sure the high voltage does not exceed the limit under any conditions.
CAUTION:
When the following parts fail, check the High Voltage after replacing.
ANODE VOLTAGE MEASURING METHOD
CAUTION: Take extra precaution when measuring this high voltage. High voltages are also present in surrounding circuit
boards (CRT DRIVE assembly, DEFLECTION assembly, and POWER SUPPLY assembly).
1. Disconnect the FBT anode cable as outlined below. Measure high voltage at the point where the cable enters the FBT.
2. Holding the rubber cover firmly, turn it counterclockwise and check that the lock has been disengaged. (See Fig. b on page
8.)
3. Determine the extent of the rubber cover before disconnecting the cable.
4. Pull straight up the anode cable to disconnect.
5. When reconnecting the cable, proceed in the reverse order.
After reconnecting, tug on the cable to check that it is secure.

CIRCUIT CHECKS

Location
Name
No.
T461 Flyback Trans.
D489 Zener Diode
Q480 Transistor
Q483 IC
R435 Resistor
R489 Resistor
R490 Resistor
R450 VR
C440 Capacitor
C443 Capacitor
C444 Capacitor
– 33 –
Name
TFB3078BD
MTZJ3.6B
2SC2023
TA7508P(J)
33k ohm, ±5%
3.3k ohm, ±5%
3.3k ohm, ±5%
1k ohm
1000pF, ±3%
6800pF, ±3%
5100pF, ±3%