Zenith B25A10Z Service Manuallines page 57

IF AND AUDIO ALIGNMENT PROCEDURE
VIDEO DETECTOR
If there is no viewable picture on screen, access the
Service Menu and check default settings for the
following items:
RFAGC
MICRO LOCATION RANGE
221-01384 17
221-01385 17
221-01386 17
221-01387 16
PIFVCO
MICRO LOCATION RANGE
221-01384 21
221-01385 21
221-01386 21
221-01387 21
Tune in a good off air signal. Place a high impedance
meter at pin 44 of ICX2200. Adjust to 2.5 volts DC.
AGC DELAY
With a strong noise free antenna signal, adjust ITEM
therefore RIF AGC on the Service Menu to a lower settings
until signal gets noisier. Increase settings for a noise
free picture.
Note: If settings goes to high above 50, the tuner
input will overload . Under certain conditions,
beats will also occur in the picture .
AUDIO DETECTOR
If no audio is present, access the Service Menu and
check default settings for the following items:
AUD LVL
MICRO LOCATION RANGE
221-01384 16
221-01385 16
221-01386 16
221-01387 16
Tune in a good strong off air signal.
Place a high impedance meter on pin 54 of ICX2200 or
from + side of capacitor C1 214. Adjust Ll 202 for 4
volts DC.
CM151
PRESET VALUE
0-63 42
0-63 42
0-63 42
0-63 42
PRESET VALUE
0-127 52
0-127 52
0-127 52
0-127 52
PRESET VALUE
0-63 46
0-63 46
0-63 46
0-63 46
MTS AND STEREO DECODER ALIGNMENT
The purpose of this procedure is adjusting registers of
SONY audio decoder and processor CXA2054S for MTS
models or audio decoder CXA2104S for STEREO models(I
1400 in both cases).
Note: Alignment should be accomplished at least ten
minutes after the TV set had been turned on.
Five register of the audio processor should be adjusted
for MTS models and three for STEREO models. Bits TEST-
DA and TEST1 should be set according with the current
adjust for MTS models (for STEREO models bits TEST-DA
and TEST1 will not be shown on the service menu because
their status do not need to be changed to do the
adjustments).
Inside of the service menu (only for MTS models):
Both TEST-DA = "0" and TESTI = "0" conditions are
selected when the internal menu is activated.
Enter the "SWAP" key of the remote control, then ten
bits registers will display in the bottom of the screen
(see the figure 1). The first one is TESTDA register and
the second one is TEST1 register.
Enter the "QUIT" key of the remote control in order to
set TESTDA = "0" and TEST1 = "1".
Enter again the "QUIT" of the remote control in order
to invert the state of the registers.
AATT Adjust
(for MTS and Stereo models)
Set bits TEST-DA = "0" and TEST1 = '0" of IC1400.
Set the chassis for RF input.
MICRO LOCATION RANGE
221-01384
221-01385
221-01386
221-01387
Input signal: PIF 30 dBmv modulated with color bars at
85% mod., SIF 19 dBmv modulated with 100 Hz at 25
KHz deviation (100 % mod.), 75 us off.
3-6
A ATT
PRESET VALUE
32 0-15 9
29 0-15 9
29 0-15 9
26 0-15 9
CA - SERVICING