Chassis Board - Loewe Xelos M55 VT Service Manual

M 1000 / M 1001
GB
Alignment
All adjustment controls not mentioned in this description are pre-set at the factory and must not be re-adjusted in the case of repairs.

Chassis Board

Measuring instruments: Digital voltmeter, colour video generator, spectrum analyser, RF millivoltmeter
Service works after replacement or repair of the following modules:
- Power supply: alignment 1.
- Tuner: alignment 2.
- IF, video demodulator: alignment 2.
- CRT, CRT panel: alignment 5...7.
- Deflection: alignment 6., 7.
- NVM IC82005: alignment 2...5., 8...9.
Alignment
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
2. Tuner AGC Spectrum analyser or RF millivoltmeter unsymmetrical to
tuner contact 10, 11.
Feed in a standard test pattern or generator via the aerial,
70...80dBµV.
Call up the dialog line "AGC" via button "M" (TV-menu)
–> Settings –> "OK" –> Special functions –> "OK" –>
SERVICE –> "OK" –> Service Code –> "8640".
3. OSD Call up the dialog line "OSD" via button "M" (TV-menu)
–> Settings –> "OK" –> Special functions –> "OK" –>
SERVICE –> "OK" –> Service Code –> "8640".
4. Tube Call up the dialog line "Tube" via button "M" (TV-menu)
(Type of picture –> Settings –> "OK" –> Special functions –> "OK" –>
tube) SERVICE –> "OK" –> Service Code –> "8640".
5. White Balance Feed in a grey scale black/white test pattern with burst.
Contrast to maximum.
Colour contrast to mid-position.
Screen brightness to mid-position.
Call up dialog line "WHITE ADJUSTMENT" via button "M"
(TV-menu) –> Settings –> "OK" –> Special functions –> "OK"
–> SERVICE –> "OK" –> Service Code –> "8640".
6. Line Sharpness Feed in a convergency test pattern.
Contrast to maximum.
Set the screen brightness so that the black
background of the test pattern just starts to brighten.
7. Screen grid Feed in a grey scale test pattern.
voltage U Adjust the screen brightness so that the gradation from the
G2
darkest grey scale value to black is just still visible.
Set the contrast to mid-value.
Measure test points R, G, B (on the CRT panel) to determine
the test point with the highest black level and connect this
point to the oscilloscope.
LOEWE.-Service
Preparations
Abgleich / Alignment / Alignement
Alignment Process
Adjust R60037 acc. to the table on the circuit diagram
mains section.
Adjust 102dBµV (360mV ) with button
pp
Alternatively, without using a spectrum analyser or RF
millivoltmeter, adjust the picture with button
noise just appears on the screen. Then reset until the
picture is again free of noise.
Terminate the dialog line "End" "with mem.".
With button or position the menu in the middle of the
picture.
Terminate the dialog line "End" "with
With button or enter the correct screen diagonal.
Terminate the dialog line "End" "with mem."
With button or set the values for "Green" and "Blue"
so that the picture becomes achromatic.
Check this alignment at minimum and maximum contrast.
Go back to the "SERVICE" menu with "M" and terminate
the dialog line "End" "with mem.".
With focus control U , adjust the vertical lines approx.
F
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.
With the control U adjust the black level at the test point
G2
with the highest black level to approx. 100V...105V for 14"
picture tubes and 150V...155V for 21" picture tubes.
Black level
100V...105V (14")
105-110V
150V...155V (21")
or .
or so that
mem.".
2 - 3