Mitsubishi Electric SD420U Service Manual page 16

Adjustment procedures
[A/D pre-amplification circuit]
1. ADC offset
Measuring
---
instrument
Test point ---
EXT trigger ---
Measurement
---
range
Input signal Shown in the table below
Input terminal COMPUTER IN terminal
Model
SD420U
SD430U
XD420U/XD430U
XD435U/XD435U-G
No. Pattern
White/black signal
29
30 SMPTE (white)*
* Though the signal generator supplies
this signal as a green signal, the
projector receives it as Y/C
signal. Therefore, this signal is
projected as a full white SMPTE
signal.
Adjustment purpose To adjust the DC level and amplitude of the video signal at the time of
ADC input.
Symptom when Solid black, solid white, or incorrect color phase appear in the projected
incorrectly adjusted
image.
* Carry out this adjustment only when the PCB-MAIN is replaced.
* Enter the adjustment commands in capital alphanumeric letters.
1. Connect the projector with a personal computer running Microsoft
98/Me/XP operating system. (Refer to the figure on page 1.)
2. Start Microsoft
3. Start the communication program [Hyper Terminal] on Microsoft
98/Me/XP to open the Hyper Terminal window. (Refer to Hyper Terminal
Setting on page 2 for the settings.)
Offset adjustment with the RGB signal supplied
Signal
4. Supply an test signal (White/black, No. 29).
5. Enter [00 ~ 5] (the command for RGB input clamp adjustment) on the Hyper
SVGA
Terminal window, and the adjustment proceeds automatically.
6. When the adjustment finishes, the return command [00 ~ 5111] is displayed on
XGA
the Hyper Terminal window. The last three digits of the return command
indicate the adjustment results of R, G, and B respectively from the left by 1 or
0. When the adjustment has succeeded, 1 is displayed. When it has failed, 0
is displayed. Possible causes of failures in the adjustment are errors on the
PCBs, wrong signals, and wrong input selection.
Offset adjustment with the component video signal supplied
7. Supply an NTSC signal (SMPTE (White), No. 30).
8. Enter [00 ~ AC1] (the command for video input clamp adjustment) on the Hyper
/C
B R
Terminal window, and the adjustment proceeds automatically.
9. When the adjustment finishes, the return command [00 ~ AC111] is displayed on
the Hyper Terminal window. The last two digits of the return command indicate
the adjustment results of C
the adjustment has succeeded, 1 is displayed. When it has failed, 0 is
displayed. Possible causes of failures in the adjustment are errors on the
PCBs, wrong signals, and wrong input selection.
 
Windows 98/Me/XP.
and C respectively from the left by 1 or 0. When
R B
- 3 -
 
Windows
 
Windows