Mal N Boar D (Pwb-1640 /1 701) Adj U Stm Ent - Tatung OMNISCAN SERIES Service Manual

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2.3 Pre-Adjustment of MAIN PCB
(PWB-1640/1701)
+12V (R211) Adjustment
A. Apply signal 89 (64KHz). full white pattern.
B. Adjust R211 so that the voltage on Pin 4 of P201
(or +12V test Pin) is 12V.
C. Check the DC voltage on Pin 3 of P201 is 5.98V
to 6.04V.
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2.4 MAIN BOARD (PWB-1640/1701)ADJUSTMENT
(1) Horizontal Hold (R422/R413/R420)
A. Short between T4 and GROUND (with 0.1uf/50V
capacitor).
B. Apply signal 89 (64KHz) and adjust H. hold 3
R422 so that the entire picture appears.
C. Apply signal 88 (48KHz) and adjust H. hold 2
R413 so that the entire picture appears.
D.
Apply signal 80 (28KHz) and adjust H. hold 1
R420 so that the entire picture appears.
NOTE: ALIGNMENT PROCEDURE
64KHz
----->
48KHz
----->
28KHz
(R422) (R413) (R420)
(2)
H. V. ADJ. (R626)
A. Brightness control and contrast control set at
fully clockwise (maximum).
B. Apply signal 89 (64KHz), FULL WHITE pattern.
C. Adjust R626 so that high voltage is 26KV.
(3) H. V. Protection (R640)
A. Apply signal 89 (64KHz), FULL WHITE pattern.
B. Adjust R626 so that protection voltage is
7.7V-7.8V.
C. Check the protection function:
Short T1 and T2, the output (high voltage)
should shut down. Open the "short" and power
on again, the high voltage will back to normal.
(4) Horizontal Raster Centering
A. Apply signal 89 (64KHz).
B. If necessary, adjust the brightness control so
that the raster is faintly illuminated.
C. If necessary, press the width control (5501/
5502) so that both edges of the horizontal raster
can be seen.
D. Select P202, P203 or P204 (either end of the
plug), until the raster is centered on the screen.
(5) Horizontal Width pre-setting (R481)
A. Apply Signal 89 (64KHz).
B. Adjust H. SIZE control 5502 to get minimum
width on the screen.
C. Adjust R481 so that the voltage on TP41 is Va
(see table).
D. Check the collector voltage of Q410 is 16.5V (+ /
- 0.5V).
E. Adjust H. SIZE control 5501 to get maximum
width on the screen.
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2-2
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