![background image](http://html.mh-extra.com/html/haier/rgbtv-25f99/rgbtv-25f99_service-manual_138207023.webp)
centering. The capacitor C238 (103) connected to (42) is for wave filtering of PH2 tester.
Line pumping signals are transmitted from (40) of N201 to line promotion triode V402
(KSC2331), and then drive the deflection coil to produce a magnetic field through the
triode tube V403 (2SD1887) after being amplified through the switch to control the
horizontal scan of the electronicbeam. C414, C415 and C427 are return capacitors, C406
is a line S correction capacitor and L402 is for line linear induction. EW geometric
correction signals are transmitted from (45) of N201, input via (12) of N301, output via
(11) of N301 after shaping, amplified through triode V401 (KSA614Y), processed by
C403 and L401 for wave shaping and then added to the line scan circuits for EW
geometric correction. The VD404A and VD404B are modem damping diodes and T444 is
a line output transformer. VD408, R416, R256, R257 and C232 form high pressure trace
circuits to compensate for the high pressure alteration as a result of brightness changes
and to automatically regulate image geometric changes caused by high pressure
alterations. R419, R239, DZ205, VD205, R270 and C226 form a beam to restrict the
electric circuits. The line return pulse output from (9) and (8) of T444 is rectified and
filtered for generating of +16.5V and +46V direct current voltage to (4) and (8) of N301
for forward and return power supply of output integrated circuits. +16.5V is regulated by
N401 (KA7812A) to 12V direct current voltage for power supply to some small
signal processing circuits, including high frequency tuner TU101 (TECC7949), sound
meter SF101(K6265K) and intermediate amplifier N101 (M9911A). (7) outputs 6.3 Vrms
filament voltage. (1) provides sync signals to the microprocessor. (5) output return pulse
to 180V direct current voltage after rectifying and wave filtering for power supply
of video amplifying circuits.
9. Analysis of video amplifying circuits
The video amplifying circuits are comprised of integrated circuits N501 (TDA6107) and
peripheral components. R, G and B screen display signals output from N901 (23), (24)
and (25), and B, G and R primary signals from (19), (20) and (21) of N201 are
transmitted to (1), (2) and (3) of N501, respectively. TDA6107 is an amplified integrated
video output circuit, including 3 video amplifiers for amplifying the input R, G and B
primary signals, and then transmitting the signals to the kinescope cathode through (7),
(8) and (9) after amplifying R, G and B primary signals input. (5) of N501 is the dark
balance checking output, from which the test results are transmitted to (18) of N201 for
adjustment of image dark balance. White balance adjustment is completed through N901
2
by output of the R, G and B primary signals of N201 under control of an I C serial bus
control system. The components of C504 (4.7u), R504 (10M
¦¸
) and VD501 (ERC2406)
form cutoff bright spot elimination circuits.
Information introducing functions and testing data for TDA6107 maintenance is listed in
Table 6. Test information is listed beneath VHFL, if a cylindrical color card is installed
then a FLUKE 79 III meter is used.
(
T a b le 6
G r o u n d R e s i s ta n c e ( R )
S t e p
F u n c t io n
W o r k i n g
V o lt a g e (V )
Po sitiv e
(
W
)
N e g a t i ve (
W
)
1
R i n p u t
3 . 2
7 . 6 K
7 . 4K
2
G i n p u t
3 . 0
7 . 6 K
7 . 5 K
3
B i n p u t
3 . 1
7 . 6 K
7 . 4 K
4
G r o u n d i n g
0
0
0
5
D a r k c u r re n t te s t o u tp u t
6 . 0
3 . 1 M
2 . 7 M
6
P o w e r s u p p l y
1 8 2 . 6
3 4 . 2 K
2 8 . 2 K
7
R c a t h o d e o u t p u t
9 7 . 6
1 . 4 M
2 . 6 M
8
G c a t h o d e o u t p u t
1 0 0 . 1
1 . 4 M
2 . 6 M
9
B c a t h o d e o u t p u t
9 3 . 4
1 . 4 M
2 . 6 M
22