Chassis Board - Toshiba 28N04D Service Manual

1. Chassis Board

Measuring instruments: Dual-channel oscilloscope, 10:1 test probe, digital voltmeter, colour video generator, spectrum analyser or RF millivoltmeter
Service works after replacement or repair of the following modules:
- Power supply: alignment 1.1
- Tuner: alignment 1.2, 1.3
- NVM IC82005: alignment 1.2 ...1.7, 2.1, 2.2, 3.1, 3.3
- Horizontal deflection: alignment 1.8
Alignment
1.1 +A voltage This voltage must be checked and re-adjusted if necessary
after every repair and before every alignment.
Brightness: Minimum
Digital voltmeter: Cathode D61016
1.2 Tuner AGC 100MHz oscilloscope or RF millivoltmeter to tuner contact
10 or 11 and tuner ground.
Colour video generator: Feed in a test pattern (sound
carrier switched off) via the aerial, 70...80dBµV.
Call up the dialog line "AGC" via " " (DIALOG CENTER) –>
"OK" –> SERVICE –> "OK" –> Service Code "8500".
1.3 AFC Reference Feed in a standard test pattern with standardized channel
spacing, band 1 (channel 2...4) without finetuning.
No adjustment
necessary with Call up the dialog line "AFC" via " " (DIALOG CENTER) –>
TDA 8843-N2 "OK" –> SERVICE –> "OK" –> Service Code "8500".
TDA 8844-N2
1.4 OSD Call up the dialog line "OSD (horizontal / vertical)" via " "
(DIALOG CENTER) –> "OK" –> SERVICE –> "OK" –>
Service Code "8500".
1.5 Tube Call up the dialog line "Tube" via " " (DIALOG CENTER) –>
(Type of picture "OK" –> SERVICE –> "OK" –> Service Code "8500".
tube)
1.6 Overscan Only with 72cm/84cm in 4:3 and 70cm/82cm in 16:9 format
Philips picture tubes.
Call up the dialog line "Overscan" via " " (DIALOG
CENTER) –> "OK" –> SERVICE –> "OK" –> Service Code
"8500".
1.7 NTSC 3.6 Call up the dialog line "NTSC 3,6" via " " (DIALOG
CENTER) –> "OK" –> SERVICE –> "OK" –> Service
Code "8500".
1.8 Line Sharpness - Feed in a convergency test pattern.
- Set the16:9 picture format (with 16:9 TV sets).
only TV's - Contrast (
with - Set the screen brightness (
Focus Block background of the test pattern just starts to brighten.
Line Sharpness - Feed in a convergency test pattern.
- Set the16:9 picture format (with 16:9 TV sets).
only TV's - Contrast (
without - Set the screen brightness (
Focus Block background of the test pattern just starts to brighten.
Preparations
{
) to maximum.
v
) so that the black
{
) to maximum.
v
) so that the black
Alignment Process
Adjust R60037 or R61313 acc. to the table (page 3-16) on
the power supply circuit diagram.
Adjust 300mV with button
pp
Alternatively, without using a oscilloscope or RF
millivoltmeter, adjust the picture with button
noise just appears on the screen. Then reset until the
picture is again free of noise.
Dialog line "End", terminate "with mem.".
Activate the setting with "OK".
Internal adjustment of the PLL demodulator is carried out.
If an arrow is displayed beside the text after adjustment, re-
adjust the AFC with demodulator filter F33025 until the
arrows disappear. The arrow on the left or right of the AFC
value in the menu indicates the direction of rotation for
adjusting the filter.
Arrow on the right, core of the filter turned in too far.
Arrow on the left, core of the filter turned out too far.
Repeat this adjustment with "OK".
Dialog line "End", terminate "with mem.".
With button or position the menu in the middle of the
picture.
Dialog line "End", terminate "with mem.".
With button or enter the correct screen diagonal.
Dialog line "End", terminate "with mem.".
Set to "on" with button or
Dialog line "End", terminate "with mem.".
Set to "off" or "on" with button
of television receiver.
Dialog line "End", terminate "with mem.".
With focus control Focus 1 adjust the horizontal lines in the
middle of the screen to minimum vertical width.
Subsequently, with focus control Focus 2, adjust the vertical
lines approx. 5cm from the right and left picture edge to
minimum horizontal width.
0
With focus control , adjust the vertical lines approx. 5cm
from the right and left picture edge to minimum horizontal
width.
The sharpness in the middle must not seem to be worse
than the sharpness at the edges. If necessary, take an
average.
or .
or so that
.
or dependent on the type
2 - 4