Adjustments - Sony GDM-20SHT Service Manual

GDM-20SHT
SECTION 4
ADJUSTMENTS
Input Signals: SONY-STD-2 (63.337 kHz x 59.978 kHz, 1280 x
1024)
1. Confirming VIDEO output waveform, and ad-
justing RV101, 201, 301
1) Enter the full white signal.
2) Set the R/G/B contrast data to "00", and confirm at the KR,
KG, KB pins of CRT socket that the pedestal voltage is as
shown below.
VP=50 V±2 V
3) Set the R/G/B contrast data to "FF", connect an oscilloscope
to the KR, KG. KB pins of CRT socket, and adjust the
RVI01, 201, 301, so that the VIDEO output waveform Vs
satisfies the following specification.
Vs KR
: 42 Vp-p ± 1 Vp-p
KG. KB : 40 Vp-p
±
1 Vp-p
2. Confirming and adjusting transient response
1) Connect respective measuring units as shown below.
Tr
=
Tf
=
2.0±0.1 ns
Pulse Gem
2) Enter the pulse signals from pulse generator to R input and
set contrast data to "FF".
3) Connect an oscilloscope probe to KR. set the time axis to 20
ms/div, and adjust the CTI0l not to allow a sag or smear in
the falling edge of waveform.
U
-'
100%
I I
I I
\ I
- - 0%
~
I
~d~~~
the trimmer
Smear
Q
~e flat
Sag
4) Press the x IOMODE button of time axis on oscilloscope. and
confirm that the Tr. Tf. undershoot, overshoot. and ringing
of waveform are within the specification.
5) If the undershoot is over the specification. readjust the trim-
mer so that the undershoot is below 12%.
Overshoot ;;;; 10%
J~
__ _
Ringing;;;;
10%
10%
I
Trm ;;;;3.8ns
.. I I ..
6) Also for the KG and KB pins of CRT socket, perform adjust-
ment given in steps (2) to
(5)
in the same manner.
(For the KG, adjust CT201; for the KB. adjust CT301)
• Landing Rough Adjustment
1. Enter the full white signal.
2. Adjust the contrast to the maximum.
3. Make the screen monogreeen. (tum off R, B input signals).
4. Reverse the DY, and adjust coarsely the purity magnet so
that a green raster positions in the center of screen.
5. Moving the DY forward, adjust so that an entire screen be-
comes monogreen.
6. Adjust the tilt of DY. and fix lightly with a clamp.
• Convergence Rough Adjustment
1. Enter the white crosshatch signal.
2. Open the hexode knob mounted at the CRT neck to 60'.
3. Adjust coarsely the horizontal convergence using the H-
STAT VR on the board A.
4. Adjust coarsely the vertical convergence through the V-
ST AT bus adjustment.
XBV
DY spacer
Purity magnets
H.STAT VR
(RV2)
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