Toshiba 27AF42, Service Manual

Page: 15 / 38

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GENERAL ADJUSTMENTS
SPECIFIC INFORMATIONS
CIRCUIT CHECKS
Troubleshooting Guide for Fail Safe Circuit
Check that the set returns to normal operation when pin 12
of Z801(or emitter of Q472) is grounded with jumper wire.
Check the voltage across
Capacitor C471 is
approximately (C) volts.
Refer to table –4 for
fail safe voltage (C) .
Faulty power
circuit or hori-
zontal circuit.
Defective Fail Safe Circuit
(See SETTING & ADJUSTING
DATA on page16)
YES NO
NO
YES
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 second an-
ode of the picture tube.
2. Turn on the receiver. Set the BRIGHTNESS and CON-
TRAST controls 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 16)
4. Vary the BRIGHTNESS control to both extremes to be sure
the high voltage does not exceed the limit under any con-
ditions.
FS CIRCUIT CHECK
The Fail Safe (FS) circuit check is indispensable for the final
check in servicing. Checking should be done following the
steps below.
1. Turn the receiver on and press the RESET button.
2. Temporarily short TP-(R) and TP-(X) with a jumper wire.
Raster and sound will disappear.
3. The receiver must remain in this state even after removing
the jumper wire. This is the evidence that the FS circuit is
functioning properly.
4. To obtain a picture again, temporarily turn the receiver off
and allow the FS circuit more than 5 seconds to reset. Then
turn the power switch on to produce a normal picture.