Service Manuals, User Guides, Schematic Diagrams or docs for : ADVENT TV Advent HT2751

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Advent HT2751


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SERVICE

MANUAL
                                          CONTENTS

1. INSTRUCTION..........................................................................................1
2. ALIGNMENT PROCEDURE..........................................................................2
3. FOR FACTORY MENU ADJUSTMENT SEE CHART5~CHART11.........................5
4. GENERAL DESCRIPTION OF THE SDA 9380-B21..........................................10
5. INTRODUCTION OF THE VPC 3230D........................................................12
6. INTRODUCTION OF THE MSP 3425G.........................................................14
7. GENERAL DESCRIPTION OF THE PW1235................................................15
8. GENERAL DESCRIPTION OF THE TDA6111Q.............................................18
WIRING DIAGRAM..................................................................................20
BLOCK DIAGRAM....................................................................................21
SCHEMATIC DIAGRAM............................................................................22
ELECTRICAL PARTS LIST........................................................................27




                                                   0
    CAUTION: THIS SERVICE MANUAL IS ONLY FOR PROFESSIONAL SERVICE PERSONNEL'S
                 REFERENCE. BEFORE SERVICING THIS CHASSIS, PLEASE READ THE
                 FOLLOWING NOTICE ITEMS.



1.     INSTRUCTION
    Before servicing and aligning this equipment, please read the following "X-RAY RADIATION
    PRECAUTION" ,"SAFETY PRECAUTION" and "PRODUCT SAFETY NOTICE".


1.1 X-RAY RADIATION PRECAUTION
1    Excessive high voltage can produce potentially hazardous X-RAY RADIATION. To avoid such
     hazards, the high voltage must not be above the specified limit. The normal value of the high
     voltage of this receiver see below chart:
                                      Chart 1 High voltage requirement
                                      High voltage normal
              Model                                               Utmost value        Beam current
                                            value
 T2751                              30 kV   1 kV                35 kV            1.6 mA
 T3251                              30 kV   1 kV                35 kV            1.6 mA



2    Each time a receiver requires servicing, the high voltage should be checked following the HIGH
     VOLTAGE CHECK procedure in this manual. It is recommended the reading of the high voltage
     be recorded as a part of service record. It is important to use an accurate and reliable high voltage
     meter.
* When checking, main power (B+) should be kept at 135 V (for Toshiba pure flat CRT).
3     The primary source of X-RAY RADIATION in this TV receiver is the picture tube. For continuous
     X-RAY RADIATION protection, the replacement tube must be exactly the same type tube as
     specified in the parts list.
4     Some parts in this receiver have special safety-related characteristics for X-RAY RADIATION
     protection. For continuous safety, parts replacement should be undertaken only after referring to
     the PRODUCT SAFETY NOTICE below.

1.2 SAFETY PRECAUTION
WARNING:
Service should not be attempted by anyone unfamiliar with the necessary precaution on this receiver.
The following are the necessary precautions to be observed before servicing this chassis.
1) Since the power supply circuit of this receiver is directly connected to the AC power line, an
     isolation transformer should be used during any dynamic service to avoid possible shock hazard.
2) Always discharge the picture tube anode to the CRT conductive coating before handling the
     picture tube. The picture tube is highly evacuated and if broken, glass fragments will be violently
     expelled. Use shatter proof goggles and keep picture tube away from the unprotected body while
     handling.
                                                            1
3) When replacing a chassis in the cabinet, always be certain that all the protective devices are put
      back in place, such as: non-metallic control knobs, insulating covers, shields, isolation
      resistor-capacitor network etc.
4) When replacing parts or circuit boards, disconnect the power cord.
5) When replacing a high wattage resistor (oxiode metal film resistor) on the circuit board, keep the
      resistor 10mm (1/2in) away from circuit board.
6) Connection wires must be kept away from components with high voltage or high temperature.
7) If any fuse in this TV receiver is blown, replace it with the FUSE specified in the chassis parts list.

1.3    PRODUCT SAFETY NOTICE
Many electrical and mechanical parts in the chassis have special safety-related characteristics.
These characteristics are often passed unnoticed by a visual inspection and the X-RAY RADIATION
protection afforded by them cannot necessarily be obtained by using replacement components rated
for higher wattage, etc. Replacement parts which have these special safety characteristics are
identified in this manual and its supplement electrical components having such features are shaded
on the schematic diagram and the parts list.
Before replacing any of these components, read the parts list in this manual carefully. The use of
substitute replacement parts which do not have the same characteristics as specified in the parts list
may create shock, fire, X-RAY RADIATION or other hazards.

1.4    Testing equipment
       HDTV signal generator: VG853 or other same type, 1 set.
       Signal generator: PM5515 or the same type, 1 set.
       Voltameter: FULK805A or the same type, 1 set.
       White balance alignment equipment: 1 set
       Standard testing jigs: 1 set.
       Geometry alignment equipment: 1 set.
       Alignment stick: 1 set.
       Degaussor: 1 set.


2     Alignment procedure

2.1 Instruction
a) In this chassis since there are a great amount of data needed to be set, these setting all are stored
    in E2PROM. To reduce the alignment working, use the aligned E2PROM as a female parent to
    copy and then use them. Or refer to appendix chart and preset E2PROM value and then use.
b) To conduct the alignment, the power supply should be AC120 V,60 Hz. The whole unit should be
    preheated for 30 minutes.
c) To conduct with color purity, convergence, white balance alignment or other alignment relative to
    color, the CRT should be degaussed thoroughly.
d) Since this chassis adopts modulization structure, before mounting, every module should be
     conducted with alignment.
e The factory menu's alignment should use XOCECO RC-T03-0A remote control. Press power
     switch to turn on the set, in turn press button "SLP-MUTE-AV-MENU" to enter into factory menu.
                                                    2
    Press SLP or 0 button to exit. Press MUTE button to preset before Out-factory.
f) For the supporting mode in this set see below chart 2.



                                   Chart 2   The supporting mode in this set
 Working mode        Mode instruction        H-frequency   V-frequencyHz   Alignment instruction
                                             Hz
 TV                  TV mode                 33.75k        60              Adjust firstly, every item should
                                                                           adjust
 1920*1080i/33.75K   American HDTV mode      33.75k        60              Horizontal and vertical parameter,
                                                                           white balance
 720P*576/45.125K    American HDTV mode      33.75k        60              Horizontal and vertical parameter,
                                                                           white balance
 640*480i(YCrCb)     YcbCr(15.7K,59.97HZ)    33.75k        60              Horizontal and vertical parameter,
                                                                           white balance
 640*480p(YPrPb)     Progressive             33.75k        60              Horizontal and vertical parameter,
                     DVD(31.5K,60HZ)                                       white balance


2.2 Alignment procedure
2.2.1 Module alignment
        In all the module alignment, use a normal working TV set as an alignment frock, pull the set's
         corresponding module and keep it as an example. Insert the module wanted to be check,
         then apply power to alignment.
a) AV board module
     AV interface function check: check all the AV input/outputs function, it should meet the Product
     Standard requirements.
b) Digital processing board module
     No alignment point, apply the power and check whether S-VIDEO, YCbCr, YpbPr input is normal.
c) Main board
     No alignment point. Apply the power and measure "B+" voltage, the reading should be 105V,
    check there are no assemble error, the OSD,SVM is normal, and it is OK.
2.2.2 Chassis adjustment
        Correctly insert all modules and parts, connect CRT board parts to CRT, apply power and
         check B+ voltage, the reading should be 105V. (on J332/J305)
2.2.3      The whole unit adjustment
Be sure the whole unit has been preheated for 30 minutes.
a) Focus adjustment
   1) In TV mode receive crosshatch signal, at the same time set SVM to OFF.
    2) Adjust FOCUS inductance L306 on Dynamic Power Board to make R323 dynamic focus
       voltage be 1KV+/-50V.
   3) Adjust FOCUS potentiometer on FBT and CRT to make horizontal and vertical grid both
       thinnest, and consider horizontal grid mainly.
   4) Set SVM to ON, check the whole effect.
b) Dark current (SCREEN voltage) adjustment
     In TV mode receive gray scale signal, after entering into factory menu status, press "1" button to
     enter into "FACTORY MENU 1" factory menu, first preset WHITE-R, WHITE-G, WHITE-B's
     value all to 0, adjust SCREEN potentiometer to make SCREEN LOCK on the screen lower part
                                                      3
      display OK and it is OK, at this time, if changing channel, it should not appear flyback line. This
      state should also be OK after finish adjusting the white balance.      .
c)    White balance adjustment
      Adjust on the basis of the above step, at standard status use gray scale signal to adjust.
  1   Press "1"button to firstly adjust TV input white balance: fix the testing point at about 40 nits gray
      scale, then by adjusting WHITE-R,WHITE-G and WHITE-B to make the value meet chart 3's
      requirement.
  2   Press "5" button to adjust YpbPr input white balance: use oscilloscope to measure Y signal
      output on Digital Processing Board. Adjust G-0 gray scale to make blanking level be even with
      black level, adjust G-G to make signal amplitude to be 0.7V and eight level gray scale be even,
      then adjust R-G, B-G, R-0, B-0's value to make white balance meet chart 3's requirement.

                             Chart 3: chroma coordinates requirements
        Colour temperature                                   12000K

           X coordinate                                 0.270 0.008 MPDC

           Y coordinate                                 0.283 0.008 MPDC




d) Picture size position and high voltage adjustment
In component mode input 1080I signal
           Use crosshatch and electrical circle signal, after entering into factory menu status, press "2"
           button to enter into "FACTORY MENU 2" factory menu to adjust picture's linearity. Adjust
           R339 joint point to make the V-center deflection range be within 



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