Electrical Adjustment Instructions - Magnavox MWC20T6 Service Manual

ELECTRICAL ADJUSTMENT INSTRUCTIONS

General Note: "CBA" is abbreviation for
"Circuit Board Assembly."
Note: Electrical adjustments are required after
replacing circuit components and certain
mechanical parts. It is important to perform
these adjustments only after all repairs and
replacements have been completed.
Also, do not attempt these adjustments unless
the proper equipment is available.
Test Equipment Required
1. NTSC Pattern Generator (Color Bar W/White
Window, Red Color, Dot Pattern, Gray Scale,
Monoscope, Multi-Burst)
2. AC Milli Voltmeter (RMS)
3. Alignment Tape (FL8A, FL8N), Blank Tape
4. DC Voltmeter
5. Oscilloscope: Dual-trace with 10:1 probe,
V-Range: 0.001~50 V/Div,
F-Range: DC~AC-60 MHz
6. Frequency Counter
7. Plastic Tip Driver
8. Color Analyzer
How to make service remote control
unit:
1. Prepare normal remote control unit (Part No.
NE204UD or NE209UD). Remove 4 screws from
the back lid (Fig. 1).
Screws
Remote control unit (bottom)
2. Cut off pin 10 of the remote control
microprocessor and short circuit pins 10 and 17 of
the microprocessor with a jumper wire
How to enter the Service mode:
Service mode:
1. Use the service remote control unit.
2. Turn the power on. (Use main power on the TV
unit.)
3. To enter the TV mode, press [CH. o / p] buttons
on the TV unit.
4. Press [DISC MENU] button on the service remote
control unit. Version of micro computer will display
on the CRT. (Ex: 057-001)
X-Ray Protection Test
X-Ray protection test should be done when replacing
any parts of this chassis.
1. Short both ends of R2592 (on Sub CBA).
2. Confirm that the main power turns off.
3. If the main power does not turn off, then replace
the following parts (D2591, Q2591, R2592,
R2593, R2594 and IC1201).
4. Perform steps 1 to 3 again.
1. DC 114V (+B) Adjustment
Purpose: To obtain correct operation.
Symptom of Misadjustment: The picture is dark and
unit does not operate correctly.
Test Point
TP2501(+B)
TP2504(GND)
Tape
---
Note: TP2501(+B), TP2504(GND) --- Sub CBA,
VR1601 --- Main CBA
Fig. 1
1. Connect the unit to AC Power Outlet.
2. Connect DC Volt Meter to TP2501(+B) and
TP2504(GND).
3. Adjust VR1601 so that the voltage of TP2501(+B)
becomes +114±1.0 V DC.
1-7-1
Adj. Point Mode
VR1601 ---
M. EQ. Spec.
DC Voltmeter +114±1.0 V DC
Input
---
T1200EA