Antenna Connections; Vco Adjustment; Rf Agc Adjustment; Vertical Size Adjustment - Sanyo DS25520 Service Manual

ANTENNA CONNECTIONS

This receiver is designed for UHF/VHF reception. A 75 ohm
terminal is provided for UHF and VHF receptions. When
connecting a CATV antenna system, connect the 75 ohm
coaxial cable directly to the 75 ohm terminal. For 300 ohm
VHF antenna, use an adapter (not included with the TV set).
CIRCUIT PROTECTION
Fuse F601 (4A) is included in the AC line. This fuse must be
replaced with the proper fuse (see Parts List).
CAUTION
FOR CONTINUED PROTECTION AGAINST
A RISK OF FIRE, REPLACE ONLY WITH
THE SAME TYPE 4A, 125V FUSE.
ATTENTION : POUR MAINTENIR LA PRO-
4A 125V
TECTION
D' INCENDIE UTILISER UN FUSIBLE DE
RECHANGE DE MEME TYPE 4A, 125V.
+B VOLTAGE CHECK
Connect Voltmeter + lead to TJ1 130V and – lead to ground
(TE7). Connect receiver to AC 120V line. Tune receiver to an
active channel. Reset the picture controls to the FACTORY
PRESET levels (press remote control RESET key twice).
Voltage must measure between +128.0V and +132.0V. If the
voltage is out of this range, the power circuit must be
checked. No +B adjustment is provided on this chassis.
HORIZONTAL CENTERING ADJUSTMENT
1. Tune receiver to an active channel.
2. Check that picture is in the horizontal center of TV screen.
If picture is not centered horizontally, perform steps 3 ~ 6.
3. Turn off the receiver and disconnect the AC power cord.
4. While pressing the MENU key, reconnect the AC power
cord. The Service Menu display will now appear.
5. Select NO. 03 HP (Horizontal Phase) with
6. Adjust the data with + or – key for horizontal center. To
turn off the Service Menu display, press the MENU key.

VERTICAL SIZE ADJUSTMENT

1. Tune receiver to an active channel.
2. Check the vertical size of the picture. If the vertical size is
too large or small, perform steps 3 ~ 6.
3. Turn off the receiver and disconnect the AC power cord.
4. While pressing the MENU key, reconnect the AC power
cord. The Service Menu display will now appear.
5. Select NO. 04 VS (Vertical Size) with
6. Adjust the data with + or – key for full scan. To turn off
the Service Menu display, press the MENU key.
VERTICAL CENTERING ADJUSTMENT
1. Tune receiver to an active channel.
2. Check that picture is in the center of TV screen. If picture
center is too low, change resistor R513 from 1K ohm 1/2W to
470 ohm 1W. If picture center is too high, remove resistor
R513 (1K ohm, 1/2W).
CONTRE LES RISQUES
or key.
or key.

VCO ADJUSTMENT

Note: VCO must be adjusted after IC101 (Signal Processor),
IC802 (EEPROM) or T151 (VCO Coil) is replaced.
1. Tune receiver to an active channel.
2. Set the picture controls to the Sports level.
3. Connect digital voltmeter + lead to pin 58 of IC101 and
– lead to ground (TE 7).
4. Confirm a reading of 3.6 ± 0.2 VDC.
5. If voltage is out of specifications adjust T151 for
3.6 ± 0.2 VDC.

RF AGC ADJUSTMENT

1. Tune receiver to strongest VHF station in your area.
2. Set contrast and brightness controls for maximum.
3. Turn off the receiver and disconnect the AC power cord
(120V AC line).
4. While pressing the MENU key, reconnect the AC power
cord. The Service Menu display will now appear.
5. Select NO. 42 RAD (RF AGC Delay) with
6. Adjust the data with + or – key in the direction which
causes snow to appear; then in the opposite direction
until the snow just disappears.
7 . To turn off the Service Menu display, press the MENU key.
VIDEO LEVEL
1. Connect color-bar generator to antenna terminals.
2. Turn off the receiver and disconnect the AC power cord
(AC 120V line).
3. Connect oscilloscope to TP16 (Q202 emitter) and ground.
4. While pressing the Menu key, reconnect the AC power
cord. The Service Menu will now appear.
5. Select NO. 46 VL (Video Level) with the
6. Adjust the + or – key for an oscilloscope reading of 1.0 ±
0.1 VP-P at TP16. Press the MENU key to turn off the
Service Menu display.
Figure 4.
— 7 —
or key.
or key.
1.0 ± 0.1 VP-P