Haier HT-3768 Service Manual page 18

Table 4
No. Function
1 +16V POWER SUPPLY
2 AMPLIFIED
OUTPUT
3 GROUND
4 RIPPLE FILTER
5 GROUND
6 AUDIO SIGNAL INPUT
7 NEGATIVE FEEDBACK
3. Analysis of vertical sync and vertical scan output circuits
The field sync signals segregated from compound sync signals are used to
activate the vertical frequency segregation system which commences when a set
amount of vertical sync pulse signals are tested. Of the sync pulse frequencies
obtained from segregation, some are transmitted to the vertical tooth wave
generator. The vertical frequency tooth wave, after geometric processing, is
transmitted from (16) of N204 (TMP8803SN) to (5) of vertical scan output IC
N402 (LA7840). The external resistor R443 (5.6KΩ) of N204 (16) provides a
reference current to the vertical tooth wave generator. The external capacitor
C244 (0.1uF) of pin (2) forms the vertical ramp wave. The vertical ramp wave is
sending the pin (4) of the vertical scan output integrated circuit N402 that is a
complete bridge current drive output circuit. After shaped and amplified the
vertical ramp wave is output from pin (2) of N402.
Information introducing functions and testing data for LA7840 maintenance is
listed in Table 4. if a cylindrical color card is installed then a fluke III digital
multimeter is used.
Table 5
No.
1 GROUND
2 VERTICAL SCAN WAVE OUTPUT
3 PUMP UP OUT
4 VERTICAL RAMP WAVE INPUT
5 WAVE CORRECTION
6 +25V POWER SUPPLY
7 VERTICAL SYNC DETECT
4. Analysis of horizontal sync and horizontal scan output circuits
As the horizontal oscillation circuit is installed inside N204 (TMP8803SN), . Some
AUDIO SIGNAL
Function
Grounding Resistance
Working
Positive
Voltage (V)
( )
16 0.43
7.5 0.58
0
5.1
0
1.7
2.05
Grounding Resistance (R)
Working
Positive
Voltage
(V)
0
13
25
0.95
0.75
25
0.83
18
(R)
Negative
( )
1.8
1.6
0 0
0.66 1
0 0
0.76 2
0.78 1.9
Negative
( ) ( )
0 0
0.45 1.9
0.5
0.9 1.25
0.68 1.75
0.5 2.95
0.65 1.3