If Servicing; Agc Delay; G2 Adjustment; Focus Adjustment - Zenith H19F34DT Series Service Manual

IF SERVICING

VIDEO DETECTOR
If there is no viewable picture on screen, access the
Service Menu and check default settings for the
following items:
#5 RF ADJ should be at least 30.
#6 VIF VCO ADJ set to 63.
Tune in a good off-the-air signal. Place a high-
impedance voltmeter at pin 2 of ICM2200. Set VIF defeat
to (#9) to "1", reset VIF defeat (#9) to "0". Adjust
item VIF VCO (#6) to 2.5 volts DC.

AGC DELAY

With a strong noise-free antenna signal, adjust RF DELAY
ADJ (#5) to a higher setting until the signal gets noisier.
Decrease the setting again for a noise-free picture.
Note: If the setting is too low (under 20) the
tuner input will overload. Under certain
conditions, beats may also appear in the
picture (Typical value is 35).

G2 ADJUSTMENT

Use the following procedure when resetting G2.
1. Set brightness and contrast in the Video menu to
mid range.
2. Set color level minimum.
3. Connect the output of an NTSC generator to the
antenna input on the receiver.
4. Select a color bar signal and turn color off. Adjust
the G2 control so that the range of bar pattern
starts from completely white (not overdriven) to
black. Leave visible 6 of 8 bars.
5. Return color level control to its normal setting.

FOCUS ADJUSTMENT

1. Connect the output of an NTSC generator to the
antenna input on the receiver.
2. Select white raster pattern.
3. Push menu key of remote control to observe the
OSD.
4. Adjust focus potentiometer to obtain the best fo-
cus at letters of menu.
SR25-3828VD0171B
SERVICE ADJUSTMENTS (continued)

ADJUSTMENT OF RGB CUTOFF

Note: If the Main Module or the CRT has been
replaced, G2 must be readjusted before
adjusting the RGB Cutoff.
1. Enter the Service menu to gain access to the cutoff
adjustments. (Factory mode item 00 must be set to 1
to gain access to this adjustment).
2. Set R Gain (Red) and B Gain (Blue) registers in the
Service menu to the default setting for the screen
size as listed in the service menu. See table.
3. Set color level and contrast to minimum. Set tint
mid range.
34 & 36 Series register
Control:
(39 Series)
Red Gain 20 (12)
Blue Gain 21 (13)
4. Connect the output of an NTSC generator to the
antenna input of the receiver. Set the generator to a
pure white signal, chroma off.
5. Set Factory menu registers #17/(9), #18(10), and
#19(11) to adjust cutoff controls for 34,36 & 39 se-
ries.
6. Carefully observe which color is predominant on the
CRT: Red, Green or Blue. Do not change the value of
cutoff control of this color.
7. Adjust the other two cutoff controls to obtain color
balance on the screen.
8. Select the color bars pattern from the Video generator
and turn the chroma off. Check that the TV set dis-
plays 3/4 of gray scale from white to black. If black
level is too high, readjust register #22, RF Sub Bright-
ness for Series 34 & 36. Readjust #14 RF Sub Bright-
ness for Series 39. Do not move Aux B Offset resistor.
9. Return the color level control to preset.
10.Disable the factory menu (Factory Mode item 0 must
be set to 0). Select "Preset" in the Video Menu under
picture preference.
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