Well 'Got-At' Panasonic TH-42PZ70B.....

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  • Alastair E
    Chief Womble
    • Mar 2013
    • 1963
    • U.K.

    #1

    Well 'Got-At' Panasonic TH-42PZ70B.....

    Ive been having a go at this Panasonic.

    I took this set as sorta part-ex for another set....

    Its Ex owner had been Potching around in there, practically murdered the PSU. Thankfully--He didn't own a soldering-iron!

    Its initial fault according to him, was turn on, red would flash for some seconds, go green--fans would run, then it shut down. He didnt say about any red-blinks.

    As he had heard Relays clicking--He took them apart.--Dunno what he did With 'em when they were in bits--he didnt say.....

    He handed me a Tupperware tray of screws, tinwork from the DG/D boards and the contents of the relays.....

    So--Thats all I had to go on.

    Found some replacement 5V coil relays from a Samsung PSU that I have about 6 of and popped them in, after removing the several hundred (It seemed) screws from the PSU and the ally plate its mounted on.

    While it was out, I replaced the two 1uF caps on the MC sub-boards and checked the thermal-fuse. It was O/C--Guessing this was original fault, so I repaired this.

    Set still completely dead.

    Checked the Stby 5V, --absent.

    Checked the supply to the small bridge-rec,--Absent.

    Checked all the mains-fuses--OK.

    Found two 10 ohm resistors--The 10W Ceramic ones--O/C.

    I replaced these with some 22 ohm that are physically the same size--and all I had at the time.

    Set now fires up--but no LED on front. Plasma-panel initialises and has the dull glow. Nothing else on screen.
    It was fairly obvious the original owner had removed the DG/D board and its steel tray, so I did the same.
    There was a plug off the Control-Board.

    Plug refitted and reassembled the DG/D tray.

    Now we have the 10-Blink! Thats as far as Ive gone at the moment--Break and tea were required!
    TELEFIX

    How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
    http://www.irf.com/technical-info/appnotes/an-1088.pdf
    PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!
  • Alastair E
    Chief Womble
    • Mar 2013
    • 1963
    • U.K.

    #2
    Re: Well 'Got-At' Panasonic TH-42PZ70B.....

    So--Refreshed with tea and a sticky-bun, we check over the set more closely...

    To find a not-quite-home plug, PA3 on the PA board.....

    Refitting correctly--It Works!
    TELEFIX

    How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
    http://www.irf.com/technical-info/appnotes/an-1088.pdf
    PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

    Comment

    • tom66
      EVs Rule
      • Apr 2011
      • 32560
      • UK

      #3
      Re: Well 'Got-At' Panasonic TH-42PZ70B.....

      Nice one.
      I had a TH-42PZ70BA with a blown thermal fuse and 10 blinks too. Seems to be a common issue. What did you use to replace the fuse?
      Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
      For service manual, schematic, boardview (board view), datasheet, cad - use our search.

      Comment

      • Alastair E
        Chief Womble
        • Mar 2013
        • 1963
        • U.K.

        #4
        Re: Well 'Got-At' Panasonic TH-42PZ70B.....

        I replaced the thermal with a 130 deg C one I had around.

        I dunno (havent checked yet) the temp rating of the original, but it looks as though that transformer runs pretty hot normally anyway....

        To add--I did put a little heatsink compound on all the various semi-conductors where they mount to the ally backplate of the PSU--may help keep it a little cooler....

        I started this thread--because I thought this one was gonna be a saga!
        TELEFIX

        How PLASMA SCREENS WORK, X-SUS and Y-SUS what they do--
        http://www.irf.com/technical-info/appnotes/an-1088.pdf
        PLEASE DO NOT EMAIL ME PRIVATELY FOR REPAIR ADVICE. QUESTIONS BELONG ON THE FORUM!

        Comment

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