Repairing & Testing YSUS & Buffers for Samsung 50” Plasma PS50Q96HD PS50Q97HD

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YSUS: LJ41-05121A KIT101, KIT181 UPPER BUFFER: LJ41-05121A LOWER BUFFER LJ41-05122AFE3407F BUFFER IC

Transcript of Repairing & Testing YSUS & Buffers for Samsung 50” Plasma PS50Q96HD PS50Q97HD

  • Repairing & Testing YSUS & Buffers for Samsung 50 Plasma PS50Q96HD PS50Q97HD

    YSUS: LJ41-05121A KIT101, KIT181

    UPPER BUFFER: LJ41-05121A LOWER BUFFER LJ41-05122A FE3407F BUFFER IC

    Fit the appropriate Kit for your faulty YSUS board. KIT101 or KIT181 (KIT101 is the most common Kit fitted to

    this board).

    Ensure that all the components in the Kit are fitted, including U5704 ADUM1410. If the IC is not replaced it

    can cause the buffers to fail and the knock on effect may cause the YSUS to fail again. Check and ensure the

    Transistors are soldered to both sides of the board.

    Fit the YSUS back into the TV with NO Buffers attached. (It is important the YSUS is tested WITHOUT Buffers

    so further problems can be prevented.)

    Connect the YSUS to the PSU and Control Board.

    Switch on the TV.

    Read the Voltages at the following Test Points, see Table 1 below.

    TEST POINT CN5601 EARTH VOLTAGE RANGE

    Pin 25 Heatsink on YSUS 90V - 120V

    Pin 23 Heatsink on YSUS 90V - 120V

    Pin 21 Heatsink on YSUS 40V - 80V

    Pin 19 Heatsink on YSUS 90V - 120V

    Pin 17 Heatsink on YSUS 40V - 80V

    Pin 15 Heatsink on YSUS 90V - 120V

    Pin 13 Heatsink on YSUS -14V - +10v

    Table 1

    As can be seen from the above table the Voltage readings at Pins 17 & 21 are considerably lower than the Voltages

    readings at Pins 15,19,23&25. This will mean that whatever voltage you read at these Pins within the range specified

    the Voltages at Pins 17&21 will always be lower. IF THEY ARE NOT LOWER YOU WILL HAVE ANOTHER FAULT. DO

    NOT ATTACH THE BUFFERS UNTIL YOU HAVE FIXED THIS PROBLEM. Check F5700 1A green fuse by the I/P Voltage

    plug

    Read the Voltage O/Ps of U5706, see Table2 below.

    TEST POINT U5706 O/P EARTH VOLTAGE

    SIN_2 Q5400 Q5401 DRAIN 0V

    OC2_C_2 Q5400 Q5401 DRAIN 3V

    OC1_ODD_2 Q5400 Q5401 DRAIN 3.5

    LE_2 Q5400 Q5401 DRAIN 0V

    OC1_EVEN_2 Q5400 Q5401 DRAIN 3.5V

    CLK_2 Q5400 Q5401 DRAIN 1.3V

    Table 2

    Note: None of the voltages in Table 2 should read significantly over 3.5V. If U5704

    ADUM1410 goes faulty the O/Ps will be incorrect and can cause the buffers to fail.

    Pic2

    You have now proven the YSUS to be OK and can continue with the Buffer Board Repairs.

  • TESTING THE BUFFER ICS ON UPPER AND LOWER BUFFER BOARDS

    Sometimes it is obvious which Buffer IC is faulty as they can have a hole burnt into them or the surface of the IC looks to

    be raised and slightly bubbled. Other times all of the ICs look perfectly good and you will need to diagnose exactly

    which IC or ICs are faulty. Follow the instructions below.

    Check the Vcc rail of all the Buffer ICs for a S/C. See Pic3 to locate the Test Point at CN5407. If you join

    the Upper & Lower Board together via CN5412 & CN5512, you can test all 8 ICs on their +Vcc rail in one

    go. Check Table 3 for the results.

    Pic3

    TEST POINT EARTH DIODE READING

    BLACK LEAD, SOLDER POINT

    BELOW CN5407

    RED LEAD, CN5407 PINS 1-24 0.680V GOOD

    0V S/C FAULTY

    Table 3

    This method will check all the Buffer ICs in one go to prove whether there is a direct S/C on the +Vcc

    rail. If no S/C is found it is safe to replace this Buffer Board.

    Follow Table 4 to check the O/Ps of the Buffer ICs for a fault. When there are no obvious viseable signs

    of burnt ICs.

    TEST POINT EARTH DIODE READING

    BLACK LEAD, SLIDE ACROSS

    ALL O/P PINS OF SOCKETS

    CN5401,CN5402, CN5403

    UPPER BUFFER,RED LEAD,

    CN5407 PINS 1-24

    GOOD: BETWEEN 0.6V - 0.8V

    AS A DIODE WOULD READ.

    FAULTY: ANY LOW

    READINGS. Eg: 0.2V - 0V. S/C BLACK LEAD, SLIDE ACROSS

    ALL O/P PINS OF SOCKETS

    CN5501, CN5502, CN5503

    LOWER BUFFER, RED LEAD

    CN5507 PINS 1-24

    Table 4

    Note: When looking at the O/Ps of the Buffer ICs you will see that

    each IC will drive two sockets. The Buffer Board is multilayer and the

    tracks can run within the Board.

    Eg: On the Upper Buffer, IC U5402 drives CN5401 even # pins and

    CN5402 even # pins. When taking your reading as in Table 4 you will

    be able to accurately diagnose the faulty IC with this method for all

    the ICs on both the Upper and Lower Buffer Boards. This method can

    be transferred to most Buffers of similar manufacturer.

    NB: AFTER REMOVING FAULTY ICS ALWAYS CHECK THE +Vcc RAIL AGAIN AS MORE THAN ONE IC CAN GO FAULTY!

  • Buffer IC Replacement.

    With this method you will need a Solder Iron, Solder, Fibre Tip Pen, Plastic Scraper, Heatgun, Isopropyl alcohol and a

    Flat Blade.

    Remove any heatsinks that are fitted to the IC and ALL the glue surrounding to it. We find its best to use

    something plastic to avoid damaging the track. Clean as much as you can before continuing.

    With a fibre tip pen, clean the remaining smaller bits of glue from between the pins. Make sure that you

    dont damage the track but pay special attention when removing the glue on the corners of the ic. Once all

    the glue is removed, clean the area with isopropyl alcohol.

    Remove the heat transfer pad from the underside of the board (if fitted) and solder the underside of the IC

    with fresh solder (Chipquick or Leaded solder is best). This helps to warm the IC before removal. Some

    engineers will use a preheater to warm the ic and board, and although this method works the concern is that

    unnecessary heat is transferred to the rest of the components on the board.

    Place the heatgun over the Buffer IC to heat it. You can solder the underside of the Buffer IC at the same

    time as using the heat gun to aid in the IC removal. This means that the solder is

    heated on the pins to the IC and also from underneath Our Heatgun is set to

    500degs and the Soldering Iron to 320degs.

  • Once you feel the IC is coming loose, you can either lift it with a blade

    or wait for it to fall off.

    NOTE: If all the glue isnt removed then it will smoke and may make the IC

    difficult to remove. It is important that you practise IC removal on a scrap

    board and experiment

    with the temperature that

    suits your equipment.

    You should be left with the IC removed and all of the track intact. Carefully clean the track with a soldering

    Iron and Solder Wick to ensure all old solder is removed and the area is totally flat so the new IC can be sat

    in place without any movement.

    Carry out the +Vcc Rail and Buffer IC Output tests to ensure no other IC is faulty.

    You can now refit this buffer into the TV to ensure no other picture faults are apparent with the Buffer

    board. You will notice that black lines are on the picture were the

    Buffer IC Outputs have not interlaced due to the IC being missing.

    Remove the Buffer board and begin refit the new Buffer IC.

    Put the IC into place and line up the pins.

    Solder two corners of the IC to fix it in place

    Using a Flux Pen or Flux saturate one side of the pins on the

    Buffer IC.

    Carefully solder up to each pin of the IC. The flux will help the

    solder bond with the track more efficiently and also prevent

    solder short circuiting on the other pins. Again this is something

    that Practice Makes Perfect and you will, over time, develop

    your own technique.

  • Complete the four sides of the IC until it is soldered in place.

    With a magnifier check your soldering, ensuring there are no S/Cs and all the pins are fully soldered.

    Carry out the +Vcc Rail Test to ensure there is no S/C on the +Vcc rails.

    Carry out the Buffer IC Output Test.

    The board is now ready to be fitted back into the TV.

    FAULTS THAT CAN OCCUR BY INCORRECT SOLDERING OF THE BUFFER IC

    If a pin is not soldered to the print you will see a black line across the screen.

    If two or more pins are soldered together you will see a translucent line across the screen.

    PICTURE FAULTS ATTRIBUTED TO THE YSUS BOARD

    Q5501 S/C

    R5509 O/C

    R5508 O/C

    ZD5502 S/C or incorrectly fitted.

    MISCELLANEOUS FAULTS ON THE YSUS BOARD

    A GREEN LIGHT ON THE YSUS BOARD ALWAYS INDICATES A FAULT.

    F5700 1A GREEN SOLDER IN FUSE.

    D5801, D5802, D5803 CAN GO S/C. THEY ARE SMD RECTIFIER DIODE S LOCATED AT THE SECONDARY OF

    T118 TRANSFORMER.

    T118 TRANSFORMER CAN FAIL IF THE ABOVE DIODES GO FAULTY.

    U5801 REGULATOR & C5817.

    CHECK CAPACITOR ON XSUS C4712 680uF 25V

    FOR POWER SUPPLY FAULTS PLEASE REFER TO THE OHM SUPPLIES TECHINCAL FLOWCHART PRODUCED

    SPECIFICALLY FOR THOSE BOARDS.

    Parts and Service Info Available at

    www.ohmsupplies.co.uk

    KIT101 Most common Repair Kit for the YSUS Board

    INFO01 Service information on KIT101

    KIT181 Alternative Repair Kit for the YSUS Board

    FE3407F IC28-C3.020 Buffer IC

    FLOWCHART INFO08 - For the Repair and Testing of Samsung 42 & 50 Plasma Power Boards.

    Technical Advisory Line: 0900 988 8898

    Calls charged at 50p per minute from a BT landline, other networks may vary and mobiles will cost considerably more.

    Sales Line: 0871 700 1433

    Calls charges at 10p per minute from a BT Landline, other networks may vary and mobiles will cost considerably more.

    Ohm Supplies Ltd 2013

    Technical Bulletin 4