Memorex MT1191V Schematic
Service Manual
MT1191V
19” Color Television
THIS SERVICE MANUAL IS FOR MT1191V SUFFIX A , B ,
C, D AND E CRT USAGE
V451 5721-015ST51N
DY501 4993-118
SUFFIX A SUFFIX B SUFFIX C SUFFIX D SUFFIX E
(51GGD95X)
5721-51CN020T
(510UEB22DY)
4993-060 4993-122 4993-119 4993-123
5721-028TT48N
(A48LRH93X (W))
5721-029NT48N
(A48LSD095X)
5721-031ZT48N
(A48LGS30X)
FEATURES
w On-screen graphics guide you through setup features and operations
w Automatic programming of channels allows easy selection of stations available in your viewing
area
w Sleep timer programs the TV to turn itself off at a preset time
w One day timer programs the TV to come on once at a preset time
w Weekly timer programs the TV to come on at a preset time every day
w 26 button infrared remote control allows remote operation
w VHF/UHF/CATV tuning allows reception of standard broadcasts or cable TV channels
w Closed caption decoder displays captions or half-screen text
w V-Block function
SPECIFICATIONS
AC Power Input: 120V, 60Hz
AC Power Consumption: 98Watts
Chassis Construction: IC Solid State
Picture Tube: 19” ( measured diagonally )
Speaker: 3.5 x 2 in (90 x 50 mm) Oval, 8 ohms
Tuner: 181 Channel, Freq. Synthesized
Remote Control: Infrared, Direct Access
26 Key, 2 “AA” batteries
Receiving Channels:
VHF 2 - 13
UHF 14 - 69
CATV
Mid Band 14 - 22
Super Band 23 - 36
Hyper Band 37 - 65
Ultra Band 66 - 94, 100 - 125
Sub Mid Band 1, 95 - 99
Cabinet: Monitor Style
Antenna Input Impedance 75 ohm (VHF/UHF) Coaxial Input
CAUTION:TO PREVENT ELECTRIC SHOCK, MATCH WI DE BLADE OF PLUG TO WIDE
SLOT, FULLY INSERT.
- 1 -
IMPORTANT SERVICE SAFETY INFORMATION
Operation of receiver outside of cabinet or with back remov ed involv es
a shock hazard. Work on these models should only be performed by
those who are thoroughly familiar with precautions necessary when
working on high voltage equipment.
Exercise care when servicing this chassis with power applied. Many
B plus and high voltage RF terminals are exposed which, if carelessly
contacted, can cause serious shock or result in damage to the chassis.
Maintain connecting ground lead connections between chassis,
escutcheon, picture tube dag and tuner cluster when operating
chassis.
These receivers have a “Polarized” AC line cord. The AC plug is
designed to fit into standard AC outlets in one direction only. The
wide blade connects to the “ground side” and the narrow blade
connects to the “hot side” of the AC line. This assures that the TV
receiver is properly grounded to the house wiring. If an extension
cord must be used, make sure it is of the “polarized” type.
When it is necessary to make measurements or tests with AC power
applied to the receiver chassis, an Isolation T ransf ormer must be used
as a safety precaution and to prev ent possible damage to transistors.
The Isolation Transformer should be connected between the TV line
cord plug and the AC power outlet.
Certain HV failures can increase X-ray radiation. Receivers should
not be operated with HV levels exceeding the specified r ating for their
chassis type. The maximum operating HV specified for the chassis
used in these receivers is 25 KV ± 1.0KV at zero beam current with a
line voltage of 120V AC. Higher voltage may also increase possibility
of failure in HV supply.
It is important to maintain specified values of all components in the
horizontal and high voltage circuits and anywhere else in the receiver
that could cause a rise in high voltage, or operating supply voltages.
No changes should be made to the original design of the receiver.
PROTECT YOUR CUSTOMER
1. Inspect all lead dress to make certain that leads are not pinched
or that hardware is not lodged between the chassis and other
metal parts in the receiver.
2. Replace all protective devices such as non-metallic control knobs,
insulating fishpapers, cabinet backs, adjustment and compartment covers or shields, isolation resistor capacitor networks,
mechanical insulators, etc.
3. T o be sure that no shoc k hazard e xists, a chec k f or the presence
of leakage current should be made at each exposed metal part
having a return path to the chassis (antenna, cabinet metal, screw
heads, knobs and/or shafts, escutcheon, etc.) in the following
manner.
Plug the AC line cord directly into a 120V AC receptacle . (Do not use
an Isolation Transformer during these checks) All checks must be
repeated with the AC line cord plug connection rev ersed. (If necessary,
a non-polarized adapter plug must be used only for the purpose of
completing these checks.)
If available , measure current using an accurate leakage current tester.
(Use Standard Item No. 25086,21641) Any reading of 0.4 mA or more
is excessive and indicates a potential shock hazard which must be
corrected before returning the receiver to the owner.
If a reliable leakage current tester is not availab le, this alternate method
of measurement should be used. Using tw o clip leads, connect a 1500
ohm, 10 watt resistor paralleled by a 0.15 MF capacitor in series with
a known earth ground, such as a water pipe or conduit and the metal
part to be checked. Use a VTVM or VOM with 1000 ohms per volt, or
higher sensitivity to measure this AC voltage drop across the resistor .
Any reading of 0.61 volt RMS or more is excessive and indicates a
potential shock hazard which must be corrected before returning the
receiver to the owner .
Components shown in the shaded areas on the schematic diagram
or identified by the safety mark in the replacement parts list should
be replaced only with exact Factory recommended replacement parts.
The use of unauthorized substitute parts may create shock, fire,
X-radiation or other hazard.
To deter mine the presence of high voltage, use an accurate high
impedance HV meter connected between second anode lead and
the CRT dag grounding device. When servicing the High Voltage
System remove static charge from it by connecting 10K ohm resistor
in series with an insulated wire (such as a test probe) between picture
tube dag and 2nd anode lead (AC line cord disconnected from AC
supply).
The picture tube used in this receiver employs integral implosion
protection. Replace with tube of the same type number f or continued
safety. Do not lift picture tube by the neck. Handle the picture tube
only when wearing shatter-proof goggles and after discharging the
high voltage completely. Keep others without shatter-proof goggles
away .
When removing springs or spring mounting parts from tuner, tuner
cluster or chassis, shatter-proof goggles must be worn. Keep others
without shatter-proof goggles away.
SAFETY INSPECTION
Before returning the receiver to the user, perform the following safety
checks:
AC
VOLTMETER
1500 OHMS
0.15 µF
TEST
PROBE
TO EXPOSED
METAL PARTS
TO KNOWN
EARTH GROUND
X-RAY PROTECTOR CIRCUIT CHECK
PERFORM WHENEVER HIGH VOLTAGE CIRCUITRY OR POWER
SUPPLY CIRCUITRY IS SERVICED.
1. Plug the AC Line Cord (P1) into a AC 120V, 60Hz receptacle.
2. Turn the Power Switch (S101) on and wait for about 10 minutes.
3. Connect the antenna leads to the EXT. Antenna Terminal (TE1)
and select a broadcasting station.
4. Connect DC Digital Voltmeter to TP11 (positive lead) and TP4
(negative lead).
5. Apply DC 11V between TP11 and TP9 from external equipment.
6. If picture and sound do not disappear, check IC301, D552, D553,
D554, R554, R555, R556, R557, C555 and C556.
- 2 -
te Control to select the
( ADJUSTMENT BY REMOTE CONTROL )
ADJUSTMENT MODE
The following adjustment items can be performed from menus by Remote Control as shown
below :
NOTE: The button combination and position on the Remo
adjustment items is given on page 4.
1. Press the SHIFT + ADJ. MODE buttons on the Remote Control simultaneously to bring up
the adjustment mode menu screens shown below.
2. From the menu screen, press the + or - button on the Remote Control to select the item to
be adjusted.
3. Press the MENU button on the Remote Control to enter adjustment mode for the item
selected, and the display shown below appears :
OR
COLOR 32
RED CUTOFF 127
Example:
4. Use the + or - button on the Remote Control to adjust the data for the item selected.
5. When adjustment has been completed, press the SHIFT + ADJ. MODE buttons on the
Remote Control simultaneously to return to the main menu.
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REMOTE CONTROL LAYOUT
VIDEO
VIDEO
- 4 -
IC, TRANSISTOR AND CRT COMPLEMENT
INTEGRATED CIRCUITS
IC101 TA87C-B2 Microcomputer
IC102 M24CO2B EEPROM
IC301 TA1268N IF/Video/Chroma/Deflection
IC311 NJ7809FA Voltage Regulator
IC501 AN5512 Vertical Deflection Output
IC601 STR30130 AVR
IC671 NJ7805LD Voltage Regulator and Reset
TRANSISTORS
Q101 DTC143ZS Vertical Synchronizing
Q102 2SC945(P) Horizontal Synchronizing
Q173 2SC945(P) SD Signal Buffer
Q301 2SC945(P) SIF Signal Buffer
Q302 2SA733(P) Video Buffer Amplifier
Q303 2SC945(P) Video Out
Q351 DTC143ZS Service Mode Switching
Q451 2SC1573A(R) Red Color Driver
Q452 2SC1573A(R) Blue Color Driver
Q453 2SC1573A(R) Green Color Driver
Q551 2SC1473A(R) Horizontal Driver
Q552 2SD1877 Horizontal Driver
Q601 2SC945(P) Power On/Off Relay Driver
Q801 2SC945(P) Audio Amplifier
Q802 2SA950(0) Audio Amplifier
Q803 2SC2120(0) Audio Amplifier
PICTURE TUBE
V451 51GGD95X CRT (SUFFIX A) V451 A48LRH93X(W) CRT (SUFFIX C)
V451 510UEB22(DY) CRT (SUFFIX B) V451 A48LS D095X CRT (SUFFIX D)
V451 A48LGS30X CRT (SUFFIX E)
CHASSIS REMOVAL
1. Remove 4 screws (177) from Cabinet Back (AB) and remove Cabinet Back from rear.
2. Discharge anode lead at CRT chassis ground through a 10kohm resistor.
3. Disconnect anode lead from CRT.
4. Disconnect CRT Socket P.C. board (PCB -2) from CRT(V451).
5. Disconnect 3 connectors (CN501 (DY501), CN601 (L601) and LCN801) from Main P.C.
board (PCB -1).
6. When replacing chassis, reverse the above procedure making certain that all leads are
fastened in their original places.
CRT REMOVAL
CAUTION: Wear shatterproof goggles and exercise proper handling precautions when working
around high vacuum picture tubes.
1. Remove chassis per instructions under CHASSIS REMOVAL.
2. Remove Convergence Magnet Assembly (MG451) from neck of CRT.
3. Remove Deflection Yoke (DY501) from neck of CRT
4. Remove 3 wedges (142) from CRT
5. Remove Degaussing Coil (L601) from CRT
6. Remove braid wire (331) and spring (158) from CRT
7. Lay cabinet face down on some protective material.
8. Remove 4 CRT mounting screws (156).
9. Remove CRT from Cabinet Front (AA).
10. To install new CRT, reverse above procedure.
11. Perform purity and convergence adjustments.
- 5 -
INSTALLATION AND SERVICE INSTRUCTION
CAUTION: Use an isolation transformer when performing any service on this chassis.
SHUTDOWN CIRCUIT: When the high voltage rises, there are simultaneous voltage increase
developed at terminal 6 of the Horizontal Output Transformer ( T671 ) and applied to pin 29 of IC301. If
excessive high voltage is produced, the increased voltage developed exceeds the rating of zener diode
D552 causing the Horizontal Oscillator to stop functioning and the high voltage system to shut down.
AFT ( AUTOMATIC FINE TUNING ) ADJUSTMENT
1. Remove JP200. (See Figure 1 for positioning)
2. Connect positive wire of TV signal Generator (NTSC signal, 45.75MHz, 80dBu ) to JP199 and
negative wire of TV Signal Generator to TP4.
3. Connect wire (+) of DC Digital Voltmeter to TP6 and wire (-) to TP4.
4. Adjust T202 so that the DC Digital Voltmeter reading is 2. 5V ± 0.2V.
5. Re insert JP200 and put solder.
FIG. 1
SUB TINT ADJUSTMENT
1. Connect TV Test Pattern Generator (NTSC signal, Color Bar signal, 70dB u , channel 6) to EXT.
Antenna Terminal (TE1) through TV Channel Signal Generator.
2. Connect positive lead of Oscilloscope to TP14 and negat ive lead to TP10.
3. Connect EXT. trigger of Oscilloscope to R463.
4. Set Tint control to center position. (by Remote Control).
( NOTE: For steps 5, 6 and 7 below, refer to page 3 for Adjustment By Remote Control Method).
5. Go to Adjustment Mode (1) by remote control.
6. Select SUB TINT from Adjustment Mode (1) menu screen.
7. Adjust SUB TINT level (by using + or - button on remote control) so that waveform is the same as
shown in Figure 2.
FIG. 2
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