Toshiba M-V19H01, Service Manual

Page: 125 / 166

Alignment and Adjustments (Electrical)
6-5
6-2 Electrical Adjustment (TV)
6-2-1 General Alignment Instructions
1. Usually, a color TV-VCR needs only a slight
touch-up adjustment upon installation. Check
the basic characteristics such as picture height,
focus and horizontal and vertical sync.
2. Observe the picture for good black and white
details; there should be no objectionable color
shading. If color shading is present,
demagnetize the receiver. If color shading
persists, perform purity and convergence
adjustments described below.
3. Use the specified test equipment or its
equivalent.
4. Correct impedance matching is essential.
5. Avoid overload. Excessive signal from a
sweep generator might overload the front-end
of the TV. When inserting signal markers, do
not allow the marker generator to distort the
test results.
6. Connect the TV only to an AC power source
with voltage and frequency as specified on the
back-cover nameplate.
7. Do not attempt to connect or disconnect any
wires while the TV is turned on. Make sure
that the power cord is disconnected before
replacing any parts.
8. To protect against shock hazard, use an
isolation transformer.
6-2-2 Fail Safe Circuit Check (FS)
1. The failsafe check must be the final step in
servicing.
2. Turn the power switch ON and adjust
customer controls for normal operation.
3. Temporarily short pin X to pin R on the main
board with a jumper wire. Raster and sound
will disappear.
4. The TV must remain in this state even after
removing the jumper wire. This shows that
the failsafe circuit is working properly.
5. To recover picture and sound, temporarily
turn off the TV and allow the failsafe circuit
more than 30 seconds to reset; switch power
ON to restore normal picture and sound.
6-2-3 Focus Adjustment
Adjust the focus control (T444) for well
defined scanning lines on the picture screen.
6-2-4 High Voltage Check
Caution: There is no high voltage adjustment
on this chassis. The B+ power supply (+125
volts) must be checked to ensure the correct
high voltage. The check point is the D809
cathode.
1. Connect a digital voltmeter to the second
anode of the picture tube.
2. Turn on the TV. Set the Brightness and
Contrast controls to minimum (zero beam
current).
3. The high voltage should be about 24KV.
4. Rotate the Brightness control to both extremes.
Ensure that the high voltage does not exceed
the 30KV limit under any conditions.