245BW, can't find problem. No 24 or 6.3V, standby is good.

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  • Toasty
    Badcaps Legend
    • Jul 2007
    • 4171

    #81
    Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

    Originally posted by Yaaman
    Good shot. I didn't find it because it is not in caps category. Thanks.
    Hopefully I won't need it and the new RT852 will sort it out.
    No. The problem is likely in the Zener's and possibly QT851. Lift that 24v jumper and see if 24v comes back.


    <<Oh yes RT852 shows 168R>> ??
    What does that mean? Its marking or the value you read with a meter?


    Originally posted by Yaaman
    Closest value I've at home is 1.4R 5W. Do you think it would be ok just for tests?
    Tough to say. Don't know what its original value was.


    Originally posted by selldoor
    @Toasty If he needed to replace the Long Blue cap could he use one of these?
    http://www.ebay.co.uk/itm/PANASONIC-...=e100084.m1843
    Yes, that should be fine.

    T
    Last edited by Toasty; 01-18-2014, 02:24 PM.
    veritas odium parit

    Comment

    • Yaaman
      Member
      • Jan 2014
      • 30
      • United Kingdom

      #82
      Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

      I powered it uup with this large resistor I had. Unfortunately nothing changed.
      I checked voltage on this large blue cap. Should it fluctuate from 300V to 330V-ish? Up and down all the time.
      Same unstable voltage on QM802 as per pic attached.
      Attached Files

      Comment

      • Yaaman
        Member
        • Jan 2014
        • 30
        • United Kingdom

        #83
        Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

        Originally posted by Toasty
        <<Oh yes RT852 shows 168R>> ??
        What does that mean? Its marking or the value you read with a meter?




        Tough to say. Don't know what its original value was.


        T
        Sorry I mean read value is 168R
        Oryginal value of RM801 is 0.22R 1W.

        Comment

        • Yaaman
          Member
          • Jan 2014
          • 30
          • United Kingdom

          #84
          Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

          I lifted the jumper. Still cant see 24V.
          Last edited by Yaaman; 01-18-2014, 04:09 PM.

          Comment

          • Yaaman
            Member
            • Jan 2014
            • 30
            • United Kingdom

            #85
            Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

            I will order and replace all four BZX84C22 and two LMBD2838LT1G.

            Comment

            • Yaaman
              Member
              • Jan 2014
              • 30
              • United Kingdom

              #86
              Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

              That was stupid what I've just done. I replaced blue cap with 100nF mkp and power resistor with 1.5R 5W one and powerd up. Resistor blow up loudly and two QM802 and QM802 are dead.

              I go to sleep...

              Comment

              • Toasty
                Badcaps Legend
                • Jul 2007
                • 4171

                #87
                Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                Hmmmm.....

                Could you have a bad mains cap?

                T
                veritas odium parit

                Comment

                • Yaaman
                  Member
                  • Jan 2014
                  • 30
                  • United Kingdom

                  #88
                  Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                  I checked CX801S, CX802S and CP802S (circled). I only have multimeter with capacitance test. I read CX801S - 312nf, CX802S - 315nF and CP802S - 480nF. That look fine to me.
                  Attached Files

                  Comment

                  • Yaaman
                    Member
                    • Jan 2014
                    • 30
                    • United Kingdom

                    #89
                    Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                    I'm doing a shopping list. What else possibly could blown? I'm ordering some parts from Farnell so I can get everything in one go. I'll get the zeners, 100ohm smd resistor (RT852), mains caps, 22nF cap, 0.22ohm resistor. What else?

                    Comment

                    • Toasty
                      Badcaps Legend
                      • Jul 2007
                      • 4171

                      #90
                      Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                      With no load and it blew, I'd be looking carefully at prior work.

                      In the future, use the "lamp-in-series" trick to prevent these types of surprises:

                      https://www.badcaps.net/forum/showpo...2&postcount=23

                      Make sure to use a real incandescent lamp, not any other type (no CFL or LED).

                      -----

                      Don't need those white caps. I re-read your list, and now with the pics, I saw you already replaced the mains cap with a KXG.

                      Assume you have the missing heatsink. ( Why is it off? )

                      What zener values did you choose? DZT852 and...? (just to be sure)
                      How did you determine?

                      Order more than 1 of the 100Ω. Usually a strip of 5 or 10 is minimum...?

                      Same with the 0.22Ω a couple-three won't hurt.

                      Check QT851. ( 1P type )

                      Both FETs, correct? Did you do ~exact~ replacements in the first go or subs?

                      Double check RB801S, the other power resistor.


                      T
                      veritas odium parit

                      Comment

                      • Yaaman
                        Member
                        • Jan 2014
                        • 30
                        • United Kingdom

                        #91
                        Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                        Yes I read about lamp trick, I'll try it. The heatsink is missing because 24V jumper I lifted was underneath.
                        I am away from my pc so I don't know the zener values but I've got schematic and I go by it.
                        Every part I order now is always more than I need so I have a spare.
                        First FETs I ordered were exacly the same but now I'm thinking to get replacement as per Fairchild Semicon the original are not being made.

                        Comment

                        • Yaaman
                          Member
                          • Jan 2014
                          • 30
                          • United Kingdom

                          #92
                          Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                          Hello
                          I finally received all replacement parts. I also used the lamp in series trick. Looks like it saved me a lots of trouble.
                          When I switch power on bulb comes on then after 2-3 seconds starts pulsing at almost full brightness. When I touch on/off button led comes down as well as the bulb. Stand-by is working, that for sure
                          I've no idea what's wrong. Could it be MC33067 (ICM801)?

                          Comment

                          • budm
                            Badcaps Legend
                            • Feb 2010
                            • 40746
                            • USA

                            #93
                            Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                            Did you check that red rectangular cap next the 24V transformer? I believe it is 18nF 630V it is one of the commonly fail cap, verify that it is still 0.18uF.
                            Last edited by budm; 01-30-2014, 02:55 PM.
                            Never stop learning
                            Basic LCD TV and Monitor troubleshooting guides.
                            http://www.badcaps.net/forum/showthr...956#post305956

                            Voltage Regulator (LDO) testing:
                            http://www.badcaps.net/forum/showthr...999#post300999

                            Inverter testing using old CFL:
                            http://www.badcaps.net/forum/showthr...er+testing+cfl

                            Tear down pictures : Hit the ">" Show Albums and stories" on the left side
                            http://s807.photobucket.com/user/budm/library/

                            TV Factory reset codes listing:
                            http://www.badcaps.net/forum/showthread.php?t=24809

                            Comment

                            • Yaaman
                              Member
                              • Jan 2014
                              • 30
                              • United Kingdom

                              #94
                              Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                              Yes. It's brand new and it's 22nF 630V.

                              Comment

                              • Yaaman
                                Member
                                • Jan 2014
                                • 30
                                • United Kingdom

                                #95
                                Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                                Ok that's weird one. When I let it cool down for a few minutes, after first power up the bulb comes on, then power off and on and the bulb only flash once and stays off and I have the 24V!
                                Unfortunately only until next power off/on. Then the bulb comes and stays on until I let the system cool down again.

                                Comment

                                • Yaaman
                                  Member
                                  • Jan 2014
                                  • 30
                                  • United Kingdom

                                  #96
                                  Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                                  Then the bulb comes on and pulsing the 24V slowly coming down, 1V every 2s.

                                  Comment

                                  • selldoor
                                    Slow Learner
                                    • Dec 2010
                                    • 7870

                                    #97
                                    Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                                    Whilst you are saying what you are seeing I am not so it would help if you could
                                    differentiate between bulbs? May be just me

                                    That is please say "Dim Light test Bulb" "Power led" or "ccfl" as against "bulb"
                                    Please upload pictures using attachment function when ask for help on the repair
                                    http://www.badcaps.net/forum/showthread.php?t=39740

                                    Comment

                                    • Yaaman
                                      Member
                                      • Jan 2014
                                      • 30
                                      • United Kingdom

                                      #98
                                      Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                                      I had 24V jumper lifted. When I soldered it back on the 24V gone. Now I need to switch off/on many times more to get the bulb come off, and event then I have no 24V.

                                      Comment

                                      • Yaaman
                                        Member
                                        • Jan 2014
                                        • 30
                                        • United Kingdom

                                        #99
                                        Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                                        When I say the bulb i refer to "in series bulb trick" bulb. Inverter is not even connected so I didn't mean ccfl. LED is the led on the front panel.

                                        Comment

                                        • selldoor
                                          Slow Learner
                                          • Dec 2010
                                          • 7870

                                          #100
                                          Re: 245BW, can't find problem. No 24 or 6.3V, standby is good.

                                          Have you tried with the ccfls connected - with them not connected may shut down as
                                          being faulty?
                                          Last edited by selldoor; 01-31-2014, 04:20 AM.
                                          Please upload pictures using attachment function when ask for help on the repair
                                          http://www.badcaps.net/forum/showthread.php?t=39740

                                          Comment

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