Power Supply Vs, Va Voltage Adjustment - Hitachi 42HDT79/DW2-U Service Manual

4. Vs, Va voltage adjustment
Item Power Unit Vs, Va Adjustment
Adjustment Preparations
(1) Turn on the set and perform
pre-heat run more than 1 min
on burn-in screen.
(2) Receive full black pattern signal
(or video silence signal; but the
power will be automatically turned
off after a few seconds by power
save function.)
(3) Connect voltmeter (which has an
error within 0.02V or less) leads
to Vs (or Va) and GND test points
of the power unit.
42"
Never touch this VR ! (Va)
(This is already adjusted.)
BACK TO ADJUSTMENTS
Adjustment Procedures
(1) Turn Vs ADJ to adjust Vs voltage
to be within 0.1V of the value
specified in the label on the panel.
(2) Turn Va ADJ to adjust Va voltage
to be within 0.2V of the value
specified in the label on the panel.
(3) Reconfirm that Vs voltage remains
within 0.1V of the specified value.
Readjust if it's outside of the
[Label example]
<LOT>N6
Vs= 80.0V
V =140.0V
Never touch this VR !
(This is already adjusted.)
Never touch this VR !
(This is already adjusted.)
41
Adj. point
Permissive level of voltage in
sufficient time of heat-run
performed is:
Vs: within 0.1V
Va: within 0.2V
42'': Adjusted by
55'': Need to be adjusted.
margin.
Label position (Reference)
: Upper left
Va=60.0V
If it's hard to read the voltage
Vx=60.0V
value because of the wiring
positions, write it down by a
marker at visible place in
advance.
Vs1
Vs Coarse ADJ. VR
Vs2
CN99 Vs/Va
Never touch this VR !
(This is already adjusted.)
DW2U
Refer to following
Remarks
manufacturing.
Vs Fine ADJ. VR
Test pins
(1)pin: Va
(2)pin: Vs
(3)pin: GND