Grundig ST 55 - 750 Manuale Utente

CUC 7350

Abgleich / Alignment

GRUNDIG Service

3 - 3

Alignment

1. +A Voltage

2. Line sharpness

3. Screen grid

voltage U

SG

4. Tuner-AGC

5. AFC-Reference

6. White balance

Preparations

Brightness: mimimum.
Voltmeter: cathode D61001.

Feed in the convergence test pattern.
Contrast to maximum.
Set the brightness so that the black background of the test
pattern is just brightening.

Feed in the grey scale pattern.
Contrast (

{

) minimum.

Colour contrast (

i

) minimum.

Adjust the screen brightness (

v

) so that the gradation from

the darkest grey to the black bar is just still visible.

Measure the R,G,B test points to determine the point at
which the black level is highest and connect the
oscilloscope.

Feed in a standard test pattern on a channel in the upper
range of the UHF band and store it at programme position
1. HF 

≥

1.5mV (64dB

µ

V, noise-free picture).

Switch the TV off with the mains button.
Voltmeter: tuner contact 2
Call up the Service Menu with button "

Ǻ

" (see above).

With 

Ƕ

 select the line "AGC ALIGN" in the menu.

Tune in a local station with standard channel spacing
without fine tuning at the desired programme position on
a channel as low as possible.
Call up the Service Menu with button "

Ǻ

" (see above).

With 

Ƕ

 select the line "AFC ALIGN" in the menu.

Feed in the FuBK test pattern –> Colour contrast (

i

)mini-

mum –> Contrast (

{

) maximum.

Adjust the screen brightness (

v

) so that the gradation from

the darkest grey to the black bar is just still visible.
Call up the Service Menu with button "

Ǻ

" (see above).

With 

ǵ

 select line "TV PROCESSOR".

Select alignment function 5 or 6 with 

Ƕǵ

.

 Alignment Process

With control 

 set the voltage to 

 (14" Orion ),

 (14" Philips), 

 (15...21").

With the focus control at the line transformer adjust the
horizontal lines for maximum sharpness.

With the control 

at the line transformer (below

the focus control) set the black level at the test point with
the highest black level to 

for 14" and to

for 15...21" picture tubes.

With the buttons  

Ǹ

and

Ƿ

 set the voltage to 

±

.

or:
With the buttons  

Ǹ

and

Ƿ

 tune the TV station so that noise

just starts to appear in the picture. Then tune in the reverse
direction until the picture just becomes noise-free.

On activation of AFC Reference, IC80000 adjusts the AFC
mid-value (the characters AFC ALIGN become white) and
stores this value in the memory IC87060.

If the characters are yellow (value is not correctly aligned)
correct the AFC using filter 

. Repeat several times

if necessary. The arrows 

Ǹ

  

Ƿ

 on the left and right of the

AFC value in the menu indicate the sense of rotation  for
this filter alignment.

Note:
The AFC voltage is used on station search as a comparative
value for VCR-HF playback (station identification "AV") to
readjust the modulator drift.

With the buttons 

Ǹ

   

Ƿ

 set the values for 

 and 

 so that no colour is

visible in the test pattern. The values are stored
automatically.

All adjustment controls not mentioned in this description are adjusted during production and must not be readjusted in the case of repairs.

Dual-channel oscilloscope with 10:1 test probe, colour signal generator, high resistance voltmeter

1.

 3., 8.

 3., 6.

 4., 5.

 8.

Feed in the test patterns via HF and store them at programme position 1.

For adjustments 4. thru 8. the Service Menu must be called up.

 Switch the TV on while holding down button "

Ǻ

" for 

≥

 3 seconds.

Schwarzwert

105-110V

100...105V  14"
155...160V  15...21"

Black level