2
GRUNDIG CUC 7851
Service and Special
Functions Cont’d
Socket
Diagram
Interference Diagram
IR-Data Programmer
With this menu and with the IR-Data Program-
mer 2 it is possible to store a maximum of 99
programme positions with the data for the TV
norm, Peri, 6-place station identification and the
fine tuning frequency.
The programmer AP transfers only channels
and 4-place station identifications.
Call up via the Menu Info Centre --> Special
Functions --> IR-Data Programmer.
Emergency Data
If necessary the emergency data can be read
out from the EPROM. See “Service Adjust-
ments”.
Service Adjustments
Changing the Sharpness
Call up the Info Menu --> Picture Menu -->
Sharpness, and change the value with .
Colour Registration
The colour registration function allows to
compensate for differences in the delay
between the Y-channel and the chroma
channel.
-
With the Menu guide call up the
“Colour Match” menu via the Service
Programme, Info Centre --> Special
Functions --> Service --> Code 8500.
-
With buttons correct the delay so
that the Y chroma signals coincide.
White Balance
-
Call up the White Balance menu via the
Info Centre --> Special Functions -->
Service --> code 8500.
-
With the buttons set the VG
(amplification green) and VB
(amplification blue) values so that the
white rectangular area in the middle of
the picture becomes achromatic. Store
with OK.
Tuner AGC
The automatic Gain Control offers two possibili-
ties of adjusting the delayed automatic gain
control voltage for the tuner:
1:
Feed a standard test pattern at a
channel in the upper range of the UHF
band into the aerial socket. The RF
should be 1.5mV (64dBmV).
Call up the “Tuner-AGC” menu via the
Service Programme Info Centre -->
Special Functions --> Service --> Code
8500, select “automatic” and confirm.
The control processor will set the
correct value for the delayed gain
control voltage.
2:
Feed in a standard test pattern at a
UHF channel as high as possible to
the aerial socket.
Call up the “Tuner-AGC” menu, Info
Centre --> Special Functions -->
Service --> Code 8500, select “manual”
and confirm.
With the buttons tune the TV
station so that noise just begins to
appear in the picture. Then tune in the
reverse direction until the picture just
becomes noise free. Store with OK.
AFC-Reference
The AFC control voltage influences the setting
of the station (fine tuning) on HF-reproduction
and on station search mode.
The Automatic Frequency Control is activated
only if the desired programme position is
marked with the station identification AV.
-
Tune the tuner precisely at a
programme position.
-
Call up the AFC Reference Menu via
Service Programme --> Info Centre -->
Special Functions --> Service --> Code
8500 --> with the menu guide and
activate with OK.
On activation of the AFC function a voltage level
is read out from the IF-amplifier which is used
as a reference for AV-programmes and on
station search.
Adjustment of the Screen Grid Voltage U
SG
-
Feed in a test pattern
-
With the remote control adjust the
screen brightness so that the grey
areas just become dark.
-
Switch the receiver to AV operation.
-
Connect a high-ohmic voltmeter
(series resistance 220kOhm approx.)
to the test points R, G, B and deter
mine the highest voltage.
-
With the control U
SG
on the picture
tube panel set the highest voltage
level to approx. 10V.
Adjustment of the Bridge Coil L511
-
Call up the Geometry Menu via Info
Centre --> Special Functions -->
Service --> Code 8500. Set the
horizontal amplitude to minimum.
-
Connect one test probe of a dual-
beam oscilloscope to the collector of
the transistor T572.
-
Connect the second test probe
between the diodes D502 and D503.
-
Adjust the coil L511 so that the pulse
width of both oscillogrames is
the same.
Adjustment of the Line Sharpness
With the focus control
on the adjustment
control panel adjust the lines in the north-south
direction for maximum sharpness.
TV receivers with focusing panel:
Subsequently, with the focus control
on the
focusing panel, adjust the lines in the east-west
direction for maximum sharpness.
Repeat if necessary.
Attention: For measurements on the focusing
panel use only sufficiently insulated measuring
cables and test probes with adequate electric
strength (eg. 100:1).
Videotext (VT) Matching Adjustment
At the time of delivery the control R378 is set to
the lowest high-frequency emphasis. If, despite
a perfect aerial signal, character faults occur,
turn R378 slowly until the character errors
disappear. Do not turn R378 any more as the
error rate may increase again.
During this adjustment page 199 must always
be selected anew so that it is read in anew
making it possible to evaluate the error rate.
Picture Geometry and Picture Position
Adjustment via the Remote Control Handset
For accurate adjustment of the picture a test
generator or standard test pattern should be
used. For raster corrections it is also possible to
use the integrated test pattern.
1:
Call up the Geometry Menu via Info
centre --> Special Functions --> Service
--> code 8500.
2:
If a standard test pattern is not
available, move the bar with the cursor
buttons to the menu item “Test
Pattern On”.
Attention: Start always with the “V-middle”
adjustment otherwise the other vertical deflec-
tion parameters would defy correct geometry
adjustment.
“V-Middle” Adjustment with a Colour Test
Pattern
-
Select the “V-Middle” menu. The upper
part of the picture is coloured, the
lower part is black and white.
-
With the or buttons move the three
broken lines on the left and on the right
of the indication “V-Middle” upwards or
downwards so that they coincide with
the line separating the coloured part
and the black/white part of the picture.
-
Continue with the picture geometry
adjustment via the menu and store.
V-Middle Adjustment with a Video Generator,
eg. Grundig VG 1000
-
Feed in the convergence test pattern
with standard colour bars via RF.
-
Call up the “V-Middle” menu.
-
With the or
button change the
setting so that the G-Y vector (orange
area in the centre of the picture) is just
covered.
-
Continue with the picture geometry
adjustment via the menu and store.
The “line shift” alignment influences the line
phase setting. Before this adjustment set the
horizontal amplitude to minimum and if neces-
sary correct the raster position with the “Shift
Plug”. With button
or move the picture into
the centre of the raster. Re-adjust the horizontal
amplitude with the test pattern.
3:To store this adjustment, move the bar to
“Terminate with store” and confirm with OK.
The picture geometry is set to the last stored
value whenever the receiver is switched on.
Reset:
Under the menu item “Reset” an average data
set from the ROM is stored. After inadvertent re-
adjustment during servicing, these basic values
can be re-loaded at any time. For this, move the
yellow bar to “Reset”, press the OK button. By
pressing the “AUX” button the picture geometry
is set according to this “Reset” values.
4:With the i button return to the normal menu.
