Memorex MT1125 service Manual

MT1125

SERVICE MANUAL

COLOR TELEVISION RECEIVER

ORIGINAL

MFR’S VERSION A

Design and specifications are subject to change without notice.

SERVICING NOTICES ON CHECKING

As for the places which need special attentions,
they are indicated with the labels or seals on the
cabinet, chassis and parts. Make sure to keep the
indications and notices in the operation manual.

2. AVOID AN ELECTRIC SHOCK

There is a high voltage part inside. Avoid an
electric shock while the electric current is
flowing.

3. USE THE DESIGNATED PARTS

The parts in this equipment have the specific
characters of incombustibility and withstand
voltage for safety. Therefore, the part which is
replaced should be used the part which has
the same character.
Especially as to the important parts for safety
which is indicated in the circuit diagram or the
table of parts as a mark, the designated
parts must be used.

PUT PARTS AND WIRES IN THE

4.
ORIGINAL POSITION AFTER
ASSEMBLING OR WIRING

There are parts which use the insulation
material such as a tube or tape for safety, or
which are assembled in the condition that
these do not contact with the printed board.
The inside wiring is designed not to get closer
to the pyrogenic parts and high voltage parts.
Therefore, put these parts in the original
positions.

5. TAKE CARE TO DEAL WITH THE
CATHODE-RAY TUBE

In the condition that an explosion-proof cathode­ray tube is set in this equipment, safety is
secured against implosion. However, when
removing it or serving from backward, it is
dangerous to give a shock. Take enough care to
deal with it.

6. AVOID AN X-RAY1. KEEP THE NOTICES

Safety is secured against an X-ray by consider­ing about the cathode-ray tube and the high
voltage peripheral circuit, etc.
Therefore, when repairing the high voltage pe­ripheral circuit, use the designated parts and
make sure not modify the circuit.
Repairing except indicates causes rising of high
voltage, and it emits an X-ray from the cathode­ray tube.

7.PERFORM A SAFETY CHECK AFTER
SERVICING

Confirm that the screws, parts and wiring which
were removed in order to service are put in the
original positions, or whether there are the
portions which are deteriorated around the
serviced places serviced or not. Check the
insulation between the antenna terminal or
external metal and the AC cord plug blades.
And be sure the safety of that.

(INSULATION CHECK PROCEDURE)

1.

Unplug the plug from the AC outlet.

2.

Remove the antenna terminal on TV and turn
on the TV.

3.

Insulation resistance between the cord plug
terminals and the eternal exposure metal
[Note 2] should be more than 1M ohm by
using the 500V insulation resistance meter
[Note 1].

4.

If the insulation resistance is less than 1M
ohm, the inspection repair should be
required.

[Note 1]

If you have not the 500V insulation
resistance meter, use a Tester.

[Note 2]

External exposure metal: Antenna terminal

HOW TO ORDER PARTS

Please include the following informations when you order parts. (Particularly the VERSION LETTER.)

1. MODEL NUMBER and VERSION LETTER
The MODEL NUMBER can be found on the back of each product and the VERSION LETTER can be

found at the end of the SERIAL NUMBER.

2. PART NO. and DESCRIPTION
You can find it in your SERVICE MANUAL.

IMPORTANT

Inferior silicon grease can damage IC's and transistors.
When replacing an IC's or transistors, use only specified silicon grease (YG6260M).
Remove all old silicon before applying new silicon.

A1-1

CONTENTS

SPECIFICATIONS....................................................................................................................................

SERVICING NOTICES ON CHECKING ...................................................................................................

HOW TO ORDER PARTS........................................................................................................................

IMPORTANT ............................................................................................................................................

CONTENTS ..............................................................................................................................................

GENERAL SPECIFICATIONS..................................................................................................................

DISASSEMBLY INSTRUCTIONS

1. REMOVAL OF ANODE CAP.........................................................................................................

2. REMOVAL OF DEFLECTION YOKE ...........................................................................................

SERVICE MODE LIST .............................................................................................................................

CONFIRMATION OF USING HOURS.......................................................................................................

NOTE FOR THE REPLACING OF MEMORY IC .....................................................................................

ELECTRICAL ADJUSTMENTS................................................................................................................

MAJOR COMPONENTS LOCATION GUIDE ..........................................................................................

BLOCK DIAGRAM...................................................................................................................................

PRINTED CIRCUIT BOARDS

MAIN/CRT ......................................................................................................................................

SCHEMATIC DIAGRAMS

MICON/TUNER ..............................................................................................................................

CHROMA ......................................................................................................................................

DEFLECTION/CRT ........................................................................................................................

POWER ..........................................................................................................................................

SOUND AMP ..................................................................................................................................

WAVEFORMS .........................................................................................................................................

MECHANICAL EXPLODED VIEW ...........................................................................................................

MECHANICAL REPLACEMENT PARTS LIST........................................................................................

ELECTRICAL REPLACEMENT PARTS LIST ........................................................................................

COVER
A1-1
A1-1
A1-1
A2-1
A3-1~A3-4

B-1
B-2
C-1
C-1
C-1
D1-1~D2-1
D3-1
E-1, E-2

F-1~F-4
G-1, G-2

G-3, G-4
G-5, G-6
G-7, G-8
G-9, G-10
H-1~H-3
I-1
J1-1
J2-1, J2-2

A2-1

G E N E R A L S P E C I F I C A T I O N S

G-1.Outline of the Product

25 inch( 626 mmV):Measured d iagonally
Color CRT 100 degree deflection

G-2.Broadcasting Syst em

US System M
G-3.Color System NTSC PAL SECAM or Monochrome signal
G-4.NTSC Playback(PAL 60Hz) Yes No
G-5.NTSC 3.58+4.43/PAL60Hz Yes No
G-6.Antenna Input Impedance

VHF/UHF 75 ohm unbalanced
G-7.Tuner and Receiving Contactless Electric tuner 1Tuner System

2Tuner System

channel Tuner Oscar(W/O HYPER) Oscar(W/ HYPER)

France CATV) Others

Receiving channel

VHF (LOW) 2 ch~ 6 c h

(HIGH) 7 ch ~ 13 c h

(CATV) A5 ch~ I ch J c h~ W+29 ch GGG ch~ W+84 c h

UHF 14 ch~ 69 ch

Tuning System

Frequency syn. Voltage syn. Others

G-8.Preset Channel

-- channels

G-9.Intermediate Frequency

Picture(fP) 45.75 MHz MHz MHz

Sound (fS) 41.25 MHz MHz MHz

fP-fS 4.50 MHz MHz MHz
G-10.Stereo/Dual TV Sound

Yes( NICAM GERMAN USA JAPAN) No
G-11. Tuner Sound Muting Yes No
G-12.Power Source 120 V AC 50Hz AC 60Hz
G-13.Power Consumption: 130 W at AC 120 V 60 Hz

W at DC V
Stand by: 8 W at AC 120 V 60 Hz
Per Year: - kWh / Year

G-14.Dimensions(Approx.)

618 mm(W) 504 mm(D) 525 mm(H)

G-15.Weight(Approx.) Net : 27 kg ( 59.9 lbs)

Gross: 29 kg ( 64.3 lbs)

G-16.Cabinet Material

Cabinet Front: PS 94HB DECABROM

AB S 94V2 NON-DECA

94V0

Back Panel: PS 94HB DECABROM

AB S 94V2 NON-DECA

94V0

A 3 - 1

G E N E R A L S P E C I F I C A T I O N S

G-17. Protector: Power Fuse
G-18.Regulation

S afety

UL CSA SAA SI CE SEV
BS NF NEMKO FEMKO DEMKO IEC65
SEMKO NZ HOMOLO SABS CNS SISIR
NOM AS3159 DENTORI UNE GOST NONE

Radiation

FCC DOC FTZ PTT CE SEV
SABA SI NF NZ HOMOLO UNE
CNS CISPR13 DENTORI AS/NZS NONE

X-Radiation

PTB DHHS HWC DENTORI NONE

G-19.Temperature

Operation 5 ºC~ 40 ºC

Storage -20 ºC~ 60 ºC
G-20.Operating Humidity Less than 80 %RH
G-21.Clock and Timer

Sleep Timer Yes Max 120 Min.( 10 Min. Step) No

On/Off Timer Yes Programs No

Wake Up Timer Yes Programs No
G-22.Timer back up Time

More than -- Minutes (at Power Off Mode)
G-23.Terminals

VHF/UHF Antenna Din Typ e F-Type France Type
Video Input(Front) Phono Jack ( R CA ø8.3) BNC
Video Input(Rear) Phono Jack ( R CA ø8.3) BNC
Video Output(Rear) Phono Jack ( R CA ø8.3) BNC
Audio Input(Front) Phono Jack ( R CA ø8.3)
Audio Input(Rear) Phono Jack ( R CA ø8.3)
Audio Output(Rear) Phono Jack ( R CA ø8.3)
21 Pin DC Jack(Center +) Ear Phone Jack(ø3.5)
Head Phone Jack(ø3.5) AC Outlet Ext Speaker
Diversity S Input(Front) S Input(Rear)

G-24.Indicator

Power Stand B y On Timer NONE

( ) ( ) ( )
G-25.Display

On Screen Display

Menu Clock Set( 12H 24H) System Selec On/Off Timer

Control Level Sound Brightness Contrast

Stereo,Audio Output,Bilingual Picture Menu
Stereo,Audio Output,SAP Mid Night Theater
Stereo,Audio Output GAME
CH/AV Clock Pin Code Hotel Lock
Sleep Timer Sound Mute Channel

Hotel Lock Area Code CH Tuning
Sound 1/2 NICAM Auto Off Picture
Guide CH Se t Audio Language
CATV Pin Code Registration V-Chip

Color Tint(NTSC Only) Sharpness
Tuning Bass Treble
Balance Back Light

A 3 - 2

G-26.OSD Langua g e

Eng Ger Fre Spa Ita Por Jpn

OSD Language Setting

Eng Ger Fre Spa Ita Por Jpn
Not Applicable

G-27.Speaker

1.5 x 2.7 inches Imp. 32 ohm x 2 pcs

Max 2.5 + 2.5 W (Typical)

10% 2.0 + 2.0 W (Typical)
G-28.EXT Speaker

Yes -- W Imp -- ohm

G-29.Carton

Master Carton: Need No Need

Content: ---- Set

Material: ---- / ---- Corrugated Carton

Dimensions: ---- mm(W) ---- mm(D) ---- mm(H)

Description of Origin Yes No

Gift B ox

Material AB Double/Brown Corrugated Carton ( with Photo Label)

Dimensions: 689 mm(W) 577 mm(D) 620 mm(H)

Design: As Per BUYER ' s

Description of Origin: Yes No

Drop Test Natural Dropping At 1 Corner / 3 Edges / 6 Surfaces

Container Stuffing: 204 Sets / 40' container

G E N E R A L S P E C I F I C A T I O N S

AB Double/White Corrugated Carton ( with Photo Label)
AB Double Full Color Carton W/Photo

Height 25cm 31cm 46cm 62cm 80cm

G-30.Accessories

Owner's Manual ( W/Guarantee Card) [ English/French ]
AC Plug Adapter Channel Film
Battery (UM- 4 x 2 ) Remote Control Unit
S afety Tip Toll Free Insert Sheet
Guarantee Card Audio-Video Cord ( R CA )
Registration Card Warning Sheet
Quick Set-Up Sheet Schematic Diagram
Information Sheet U/V Mixer
75 ohm Coaxial Cable ( Single Shield Double Shield)
300 ohm to 75 ohm VHF Antenna Adaptor
21pin Cable Car Cord
Rod Antenna

Loop Antenna ( F-Type Din Typ e France Type )

G-31.Other Features

Auto Degauss Auto Search Full OSD
Auto Shut Off CH Allocation Premiere
Canal+ SAP Comb Filter
CATV(181CH) Channel Lock Auto CH Memory
Anti-Theft Just Clock Function Hotel Lock
Rental Game Position Fastext
Unitext TopText Closed Caption
Picture Menu Mid Night Theater V-Chip

One Pole Two Pole ( F-Type Din Type France Type)

A 3 - 3

G E N E R A L S P E C I F I C A T I O N S

G-32.Switch

Front

Power(Tact) Channel Up/Reset Volume Up/Set Up
System Select Channel Down/Enter Volume Down/Set Down
Main Power S W Sub Power Menu:Vol UP + Vol Down

Rear

AC/DC TV/CATV Selector
Degauss Main Power SW

G-33.Magnetic Field

BV : +0.45G BV : +0.35G BV : +0.25G

BH : 0.18G B H : 0.30G B H : 0.30G

BV : -0.15G B V : -0.25G B V : -0.50G

BH : 0.15G B H : 0.15G BH : 0.30G

G-34.Remote Control Unit: RC- 74

Power Source: D.C 3 V Battery UM - 4 x 2

Power Quick View TV/AV
Stand B y Status Bar Select
0 Time Select PAL/SECAM
1 Time S et Volume Up
2 Muting Volume Down
3 CH Skip CH Call
4 CH1/CH2 C H Down
5 Channel CH Up
6 Text/Mix/TV CH Down/Page Down
7 Display Cancel CH Up/Page Up
8 Initial P age + / ­ 9 Store Program
10 R eveal F/T/B
11 Sleep Hold
12 Aft/Skip List
1 Preset Rotate
2 5.5/6.5MHz Browse
0/10 Auto Memory Std/Auto
Tone 1/2 Auto Memory
Info Call Band Select
Mono/Auto Reset Search
TV/Caption/Text Menu Clock/Program
Expand Enter Clock/Set
Red Add Ch Se t
Cyan Delete Set +
Normal Yellow Set ­Color System Random Green
Wide Selecy Tuning Up/Time T ext Nicam/Mono
Auto Wide On/Off Tuning Down/Reset Tone A/ B
Picture Position Navi FM Transmitter
Direct Change/Auto Search Back Light
Picture Menu Mid Night Theater Stereo/Mono

A 3 - 4

DISASSEMBLY INSTRUCTIONS

1. REMOVAL OF ANODE CAP

Read the following NOTED items before starting work.
*

After turning the power off there might still be a potential
voltage that is very dangerous. When removing the
Anode Cap, make sure to discharge the Anode Cap's
potential voltage.

*

Do not use pliers to loosen or tighten the Anode Cap
terminal, this may cause the spring to be damaged.

REMOVAL

1. Follow the steps as follows to discharge the Anode Cap.

(Refer to Fig. 1-1.)

Connect one end of an Alligator Clip to the metal part of a
flat-blade screwdriver and the other end to ground.
While holding the plastic part of the insulated Screwdriver,
touch the support of the Anode with the tip of the
Screwdriver.
A cracking noise will be heard as the voltage is discharged.

GND on the CRT

3. After one side is removed, pull in the opposite direction to
remove the other.

NOTE

Take care not to damage the Rubber Cap.

INSTALLATION

1. Clean the spot where the cap was located with a small
amount of alcohol. (Refer to Fig. 1-3.)

Location of Anode Cap

Screwdriver

Alligator Clip

GND on the CRT

Flip up the sides of the Rubber Cap in the direction of the

2.
arrow and remove one side of the support.

(Refer to Fig. 1-2.)

Rubber Cap

Support

CRT

Fig. 1-1

Fig. 1-3

NOTE

Confirm that there is no dirt, dust, etc. at the spot where
the cap was located.

2.3.Arrange the wire of the Anode Cap and make sure the
wire is not twisted.
Turn over the Rubber Cap. (Refer to Fig. 1-4.)

Fig. 1-4

CRT

Support

Fig. 1-2

B-1

DISASSEMBLY INSTRUCTIONS

4. Insert one end of the Anode Support into the anode button,
then the other as shown in Fig. 1-5.

Support

CRT

5.6.Confirm that the Support is securely connected.
Put on the Rubber Cap without moving any parts.

2. REMOVAL OF DEFLECTION YOKE

(Refer to Fig. 2-1)

1.

Loosen the screw 1.

2.

Remove the Convergence • Purity Magnet in the
direction of arrow (A).

3.

Loosen the screw 2.

4.

Remove the 3 Wedges.

5.

Remove the Deflection Yoke in the direction of arrow
(B).

Fig. 1-5

2

Wedge

Wedge

INSTALLATION

Install new Deflection Yoke in reverse steps of REMOVAL.

NOTE

After adjusting the purity and the convergence, fix the
screw 2 and lock the wedges.

(B)

Deflection Yoke

1

(A)

Convergence •
Purity Magnet

Fig. 2-1

B-2

SERVICE MODE LIST

This unit provided with the following SERVICE MODES so you can repair, examine and adjust easily.

Set Key Remocon Key Operations

VOL. (-) MIN

0

Releasing of V-CHIP PASSWORD.

VOL. (-) MIN 1

VOL. (-) MIN 6

VOL. (-) MIN 8

VOL. (-) MIN

9

Initialization of the factory.
NOTE: Do not use this for the normal servicing.

POWER ON total hours is displayed on the screen.
Refer to the "CONFIRMATION OF USING HOURS".

Can be checked of the INITIAL DATA of MEMORY IC.
Refer to the "NOTE FOR THE REPLACING OF MEMORY IC".

Writing of EEPROM initial data.
NOTE: Do not use this for the normal servicing.

Display of the Adjustment MENU on the screen.
Refer to the "ELECTRICAL ADJUSTMENT" (On-Screen Display Adjustment).

CONFIRMATION OF USING HOURS

POWER ON total hours can be checked on the screen. Total hours are displayed in 16 system of notation.

1.

Set the VOLUME to minimum.

2.

Press both VOL. DOWN button on the set and the Channel
button (6) on the remote control for more than 2 seconds.

3.

After the confirmation of using hours, turn off the power.

ADDRESS DATA

INIT 00 83
CRT ON

0010

FIG. 1

Initial setting content of MEMORY IC.
POWER ON total hours.

= (16 x 16 x 16 x thousands digit value)
+ (16 x 16 x hundreds digit value)
+ (16 x tens digit value)
+ (ones digit value)

NOTE FOR THE REPLACING OF MEMORY IC

If a service repair is undertaken where it has been required to change the MEMORY IC, the following steps should be taken to
ensure correct data settings while making reference to TABLE 1.

NOTE: No need the setting for after INI 09.

ADDRESS

DATA

1.

Enter DATA SET mode by setting VOLUME to minimum.

2.

Press both VOL. DOWN button on the set and the Channel button (6) on the remote control for more than 2 seconds.

3.

ADDRESS and DATA should appear as FIG 1.

4.

ADDRESS is now selected and should "blink". Using the SET + or - keys on the remote, step through the ADDRESS until
required ADDRESS to be changed is reached.

5.

Press ENTER to select DATA. When DATA is selected, it will "blink".

6.

Again, step through the DATA using SET + or - until required DATA value has been selected.

7.

Pressing ENTER will take you back to ADDRESS for further selection if necessary.

8.

Repeat steps 4 to 7 until all data has been checked.

9.

When satisfied correct DATA has been entered, turn POWER off (return to STANDBY MODE) to finish DATA input.

The unit will now have the correct DATA for the new MEMORY IC.

INI00INI01INI02INI03INI04INI05INI06INI07INI08INI

09

88 6C 80 00 00 00 00 98 07 04

Table 1

C-1