Haier HT-3718 User manual

HT-3718
Service Manual
COLOUR TELEVISION
Precautions.................................1
I.
Specifications..............................5
2.
Alignment and Adjustments.........7
3.
SchematicDiagrams...................56
8.
BolckDiagram.............................55
7.
ElectricalParts List.....................41
6.
Exploded Views and PartsList....40
5.
Troubleshooting...........................34
4.
Features
2
I C bus control
Turning TV on/off with curtain-fashion
218 programmes stored
Entire channel CATV(470MHZ)
Multi-picture and multi-volume modes selection
Audio/Video input and output,S-Video terminal
Black background protection without signal
On-time,off-time,appointing programme
English OSD
Childlock
Haier group

1.PRECAUTIONS
INPORTANT SAFETY NOTICE
These parts are identified by many electrical and mechanical parts in this chassis have special
safety-related characteristics. ！in the Schematic Diagram and Replacement Parts List.
It is essential that these special safety parts should be replaced with the same components as
recommterminaled in this manual to prevent X-RADIATION, Shock, Fire, or other Hazards.
Do not modify the original design without permission of the manufacturer.
General Guidance
An Isolation Transformer should always be used during the servicing of a receiver whose
chassis is not isolated from the AC power line. Use a transformer of adequate power rating as
this protects the technician from accidents that might result in personal injury caused by
electrical shocks.
It will also protect the receiver and it’s components from being damaged by accidental shorts
of the circuitry that might be inadvertently introduced during the service operation.
If any fuse (or Fusible Resistor) in this TV receiver is blown, replace it with a specified one.
When replacing a high wattage resistor (Oxide Metal Film Resistor, over 1W), keep the
resistor 10mm away from PCB.
Keep wires away from high voltage or high temperature parts.
Due to the high vacuum and large surface area of the picture tube, extreme care should be
taken in handling the Picture Tube. Do not lift the Picture Tube by its Neck.
X-RAY Radiation
Warning:
The source of X-RAY RADIATION in this TV receiver is the High Voltage Section and the
Picture Tube.
For continued X-RAY RADIATION protection, the replacement tube must be of the same
type as specified in the Replacement Parts List.
Before returning the receiver to the customer,
always perform an AC leakage current check on the exposed metallic parts of the cabinet,
such as antennas, terminals, etc., to make sure that the set is safe to operate without any
danger of electrical shock.

SERVICEING PRECAUTIONS
CAUTION: Before servicing receivers covered by this service manual and its supplements
and addterminala, read and follow the SAFETY PRECAUTIONS.
NOTE: If unforeseen circumstances create conflict between the following servicing
precautions and any of the safety precautions, always follow the safety precautions.
Remember: Safety First.
General Servicing Precautions
1. Always unplug the receiverAC power cord from the AC power source before:
a. Removing or reinstalling any component, circuit board module or any other assembly of
the receiver.
b. Disconnecting or reconnecting any receiver electrical plug or other electrical connection.
c. Connecting a test substitute in parallel with an electrolytic capacitor in the receiver.
CAUTION: A wrong substitution part or incorrect installation polarity of electrolytic
capacitors may result in an explosion hazard.
d. Discharging the picture tube anode.
2. Test high voltage only by measuring it with an appropriate high voltage meter or other
voltage-measuring device (DVM, FETVOM, etc.) equipped with a suitable high voltage
probe. Do not test high voltage by “drawing an arc”.
3. Discharge the picture tube anode only by (a) first connecting one terminal of an insulated
clip lead to the degaussing or kine aquadag grounding system shield at the point where the
picture tube socket ground lead is connected, and then (b) touch the other terminal of the
insulated clip lead to the picture tube anode button, using an insulating handle to avoid
personal contact with high voltage.
4. Do not spray chemicals on or near this receiver or any of its assemblies.
5. Unless specified otherwise in this service manual, clean electrical contacts only by
applying the following mixture to the contacts with a pipe cleaner, cotton-tipped stick or
comparable nonabrasive applicator; 10% (by volume) Acetone and 90% (by volume)
isopropyl alcohol (90%-99% strength)
CAUTION: This is a flammable mixture.
Unless specified otherwise in this service manual, lubrication of contacts is not required.
6. Do not defeat any plug / socket B+ voltage interlocks with which receivers covered by
this service manual might be equipped.
7. Do not apply AC power to this instrument and/or any of its electrical assemblies unless
all solid-state device heat sinks are correctly installed.
8. Always connect the test receiver ground lead to the receiver chassis ground before

connecting the test receiver positive lead.
Always remove the test receiver ground lead last.
9. Use with this receiver only the test fixtures specified in this service manual.
CAUTION: Do not connect the test fixture ground strap to any heat sink in this receiver.
Electrostatically Sensitive (ES) Devices
Some semiconductor (solid state) devices can be damaged easily by static electricity. Such
components are usually called Electrostatically Sensitive (ES) Devices. Examples of typical
ES devices are integrated circuits and some field effect transistors and semiconductor “chip”
components. The following techniques should be used to help reduce the incidence of
component damage caused by static electricity.
1. Immediately before handling any semiconductor component or semiconductor- equipped
assembly, drain off any electrostatic charge on your body by touching a known ground ground.
Alternatively, obtain and wear a commercially available discharging wrist strap device, which
should be removed to prevent potential shock prior to applying power to the unit under test.
2. After removing an electrical assembly equipped with ES devices, place the assembly on a
conductive surface such as aluminum foil, to prevent electrostatic charge buildup or exposure
of the assembly.
3. Use only a grounded-tip soldering iron to solder or unsolder ES devices.
4. Use only an anti-static type folder removal device. Some solder removal devices not
classified as “anti-static” can generate electrical charges sufficient to damage ES devices.
5. Do not use freon-propelled chemicals. These can generate electrical charges sufficient to
damage ES devices.
6. Do not remove a replacement ES device from its protective package until immediately
before you are ready to install it. (Most replacement ES devices are packaged with leads
electrically shorted together by conductive foam, aluminum foil or comparable conductive
material).
7. Immediately before removing the protective material from the leads of a replacement ES
device, touch the protective material to the chassis or circuit assembly into which the device
will be installed.
CAUTION: Be sure no power is applied to the chassis or circuit, and observe all other safety
precautions.
8. Minimize bodily motions when handling unpackaged replacement ES devices. (Otherwise
even some normally harmless motions such as mutual brushing of your clothes’ fabric or
lifting of your foot from a carpeted floor might generate static electricity sufficient to damage
an ES device.)
General Soldering Guidelines
1. Use a grounded-tip, low-wattage soldering iron and appropriate tip size and shape that will

maintain tip temperature within the range of 500oF to 600oF.
2. Use an appropriate gauge of RMA resin-core solder composed of 60 parts tin/40 parts lead.
3. Keep the soldering iron tip clean and well tinned.
4. Thoroughly clean the surfaces to be soldered. Use a mall wire bristle (0.5 inch, or 1.25cm)
brush with a metal handle. Do not use freon-propelled spay-on cleaners.
5. Use the following unsoldering technique
a. Allow the soldering iron tip to reach normal temperature.(500o F to 600o F)
b. Heating the component lead until the solder melts.
c. Quickly draw the melted solder with an anti-static, suction-type solder removal device
with solder braid.
CAUTION: Work quickly to avoid overheating the circuit board printed foil.
6. Use the following unsoldering technique
a. Allow the soldering iron tip to reach normal temperature.(500o F to 600o F )
b. First, hold the soldering iron tip and solder the strand against the component lead until the
solder melts.

2. TECHNICAL SPECIFICATION
1. PWER SUPPLY AC 90v-250v 50/60Hz
2. COLOUT SYSTEM: PAL SECAM NTSC4.43/3.58 (AV)
3.TV SYSTEM: B/GD/K
4.CRT: 14”
5. AERIAL INPUT IMPEDANCE: 75ΩStandard Coaxial Cable
6. SOUND OUTPUT POWER: ≥1W
7. POWER CONSUMPTION: ≤60W
8.NETWEIGHT(kg): 11
9. NET SIZE (mm): 440 x 355 x 335

Products functions
TYPE
FUNCTIONS
HT-3718
TYPE
FUNCTIONS
HT-3718
IC TA1238 Audio output power(w) 1W
Tube 14 Super woofer
Color system PAL SECAM
NTSC3.58/4.43(A V) NO of built-in speakers 2
Broadcast system B/G D/K Analog surround stereo
No.of preset channels 218 Treble/bass lifting and balancing
CATV band width 470MHZ Multiple audio mode
Blue/black screen black AV stereo
Menu OSD Digital reverberation
OSD language English Tone control
Manifold PIC modes Auto volume leveling
Program preview Mute
Y/C separation circuit 3D surround sound
Denoise circuit SRS
Black level extend MAX volume preset
Blue level extend 5 bands equalizer
Auto skin color correction
AUDIO
NICAM
adjustment AV in Rear 1
Dynamic high voltage stabilizing AV out Rear 1
Dynamic focusing S terminal
Double focusing DVD signal input
Dynamic white peak clipping KARAOK terminal
Color resolution lift Stereo headphone socket
4 2 2 PIC window positioning VGA
Pull-curtain type on /off display NO. of Australian standard sockets
Artificial intelligence Service terminal
SVM HI-FI audio signal output terminal
CTI External super bass terminal
LTI
TERMINA
LS
DC current output
Video signal digitalization Timer off(MINS) 120
Teletext Timer on
Still frame Auto off upon no signal
Multi PIC Frames AC off
PIP independent tuner Stand by
PIP double tuner Frequency synthesis tuning
PIC out PIC Tension synthesis tuning
9 programs preview Automatic color system identify
100Hz I2C bus-mastering
ZOOM AV in AV out
Stepless zoom in/out Wireless earphone(infrared)
16 9 mode Handset position notify(beep)
Logo configure Automatic channel preset
Skip Partial automatic channel preset
Supper receiver
CONTROL
Manual channel preset
Calendar Total power input(W) 60W
Memo book/games Voltage range(V) AC150V-250V
Favorite channels Power frequency(Hz) 50HZ
Child lock Packaged weight(Kg) 12Kg
SPECIFICA
TIONS
Packaged dimensions(mm) 500*415*390
Type of power plug
I
M
A
G
E
OTHER V-CHIP CCD
Attention: already have * you can choose it or not

3.Alignment and Adjustments
Functions:
•I 2C bus control
•Display Full Function on Screen and infrared Remote Control
•ASM System and fine Circuit, 100 Programs stored from 0 to 99
•Picture mode stored (don’t Adjust Brightness repeatedly)
•Audio/Video input and output, S-video terminal
•Twelve kinds of modes Turning OFF the TV set with defined time (120 minutes. 110
minutes. 100 minutes… 30 minutes, 20 minutes, 10 minutes)
•Blue Background and Sound Mute without Signal, Turn Off without signal after 15 minutes.
•Entire Channel TV (CATV 470 MHz)
•English

Control
A. Local control buttons
HT-3718 HT3728
①Power switch button
②Infrared sensor window
③Power indicator
④Program up/down button
⑤Volume up/down button
⑥TV/AV alternating button
⑦Menu display button
⑧Audio (R) input
⑨Audio (L) input
⑩Video input

CONNECTING TO OTHER EQUIPMENT
The sockets son the back cover
①Aerial socket
②Video input socket
③Video output socket
④Audio input socket
⑤Audio output socket
⑥S- video socket
⑦Audio output (L) socket
⑧Audio output (R) socket
Connecting to AV input sockets on the back cover
connect the video and audio outputs of a VCR OR VCD player etc. To AV input sockets of
this TV set. Tapes and discs can be played.
Connecting to the AV output sockets:
The AV output terminals can put out the picture and sound signal that the TV set played. They
are used to record TV program.
•Connect the audio output (L) or the audio output ® on the TV set to the audio input on the
mono VCR.
•When you receive S-Video video signal, you must remove video signal;
Wen you receive video signal, you must remove S-Video signal.
When you receive AV input signal, you can only select either the front AV input signal or the
back AV input signal.

1.The integrated circuit used in this set
(1) TB1238AN: Picture intermediate frequency, sound intermediate frequency, video
signal processing, chrominance signal processing, RGB output circuit and horizontal
and vertical vibration scanning circuit.
(2) TMP87CK38N: Super central microprocessor
(3) LA7830: Vertical scanning circuit.
(4) LA4275: Sound amplifier circuit.
(5) LA7910: Band alternating selection switch
2. Functions and parameters of integrated circuit
N402 LA7830
Reference resistance (KΩ)
Item
No. Function Reference voltage (V) Forward Reverse
1 Grounding terminal 0 0 0
2 Output terminal 13 0.45 1.9
3 Pump power output
terminal 26 0.5
∞
4 Vertical scanning
saw-tooth wave signal
input terminal
0.95 0.9 0.25
5 Vertical scanning
saw-tooth wave signal
generating terminal
0.75 0.68 1.75
6 Vertical power terminal 26 0.5 2.95
7 Vertical power input
terminal 0.83 0.65 1.3
N701 LA4275
Reference resistance (KΩ)
Item
No. Function Reference voltage (V) Forward Reverse
1 Ground 0 0 0
2 Amplifier output 10 0.55 4.5
3 Power supply 19 0.42 2.8
4 Ripple filtering 10 1.2 2.4
5 Ground 0 0 0
6 Audio input 0.1 1.1 ∞
7 feedback 0.2 0.72 2.0

N251 TN1275AZ Reference resistance (KΩ)
Reference voltage (V)
Pin Function With
signal Without signal
Forward
(black
grounding)
Reverse (red
grounding)
1 Y output 2.96 7.8 11
2 Delay switch 4.04 7.2 9.5
3 R-Y output 2.43 7.8 11
4 R-Y output 0.31 7.0 8
5 B-Y output 2.44 7.8 11
6 B-Y blanking control 0.31 7.0 8
7 Recognition filter 4.54 7.8 11
8 Vacant 2.58 7.8 10.5
9 Power supply 5.06 1.6 1.6
10 Vacant 2.58 7.8 11
11 B-Y input 0 0 0
12 Frequency filter 2.86 7.8 9.6
13 S/chrominance low pass
filter 4.34 7.5 11
14 Clock filter 2.39 7.8 11
15 Y input 2.77 7.8 11
16 Clock control 5.09 1.6 1.6
17 Sandcastle impulse input 0.69 6.6 7.5
18 Power supply 5.09 1.6 1.6
19 4.43 threshold input 1.49 7.5 9.6
20 Ground 0 0 0
21 System recognition switch 1.54 7.6 0
N201 TB1238AN
Reference Voltage(V) Reference Resistance(KΩ)
Pin Function
Without
signal With signal Forward(Ω) Backward(Ω )
1 Unweighted 5.0 5.0 800 2000
2 Audio signal output 3.5 3.5 750 2000
3 PIF circuit power supply 9.0 9.0 460 600
4 AFT output and
auto-adjusting 2.0 2.0 750 600
5 PIF circuit grounding 0 0 0 0
6 IF signal input pin 1.4 1.4 680 2000
7 IF signal input pin 1.2 1.2 680 2000