Panasonic TH-P42X30A no standby 5 volt

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • dkneyle
    Badcaps Veteran
    • Dec 2013
    • 441
    • Australia
    #1

    Panasonic TH-P42X30A no standby 5 volt

    [Posting this fault find to help others who might follow later.]

    Got this plasma from the dump/tip. Great looking TV with high quality features. Completely dead. No standby supply. Have traced the hot side standby supply through and appears to be OK but have not confirmed that it is actually oscillating. Looking on the cold side I see a SMT diode that appears to rectify the output of the standby transformer. It measures short circuit in circuit. I am about to remove it from the circuit and test out of circuit. Having difficulty reading the type number. I thought I saw LT1402 but nothing appropriate comes up on a Google search.
    Tags: None
    • ReeceyBurger123
      Never Give Up !
      • May 2014
      • 7325
      • Britain
      #2
      Re: Panasonic TH-P42X30A no standby 5 volt

      Normally that diode is in place to protect the transformer so it probably will show S/C in circuit but fine out of circuit. Can you provide us with some pictures please ?
      Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

      https://www.facebook.com/Telford-Tel...7894576335359/

        Comment

        • dkneyle
          Badcaps Veteran
          • Dec 2013
          • 441
          • Australia
          #3
          Re: Panasonic TH-P42X30A no standby 5 volt

          The suspect diode is D308. You can pretty well follow the circuit by looking at the PCB tracks. The diode sits on the output of the standby transformer and half-wave rectifies the high frequency AC. The filter cap C325 does its job at the output of the diode in question. It does not appear to be a snubber diode.
          Attached Files

            Comment

            • ReeceyBurger123
              Never Give Up !
              • May 2014
              • 7325
              • Britain
              #4
              Re: Panasonic TH-P42X30A no standby 5 volt

              You are right now that im looking at it, test it out of circuit and see buddy,
              Please Do Not PM My Page Asking For Help Badcaps Is The Place For Advise, Page Linked For Business Reasons Only. Anyone Doing So Will Be Banned Instantly !

              https://www.facebook.com/Telford-Tel...7894576335359/

                Comment

                • dkneyle
                  Badcaps Veteran
                  • Dec 2013
                  • 441
                  • Australia
                  #5
                  Re: Panasonic TH-P42X30A no standby 5 volt

                  Just pulled it and it is short circuit. Have gone through my junk pile and found a diode from another SMPS that appears to do the same job in circuit. It's a SB2H00. I'll just check its specs then drop it in and see what happens.

                    Comment

                    • dkneyle
                      Badcaps Veteran
                      • Dec 2013
                      • 441
                      • Australia
                      #6
                      Re: Panasonic TH-P42X30A no standby 5 volt

                      All fully operational again. I thought perhaps a short circuit diode would indicate other overload problems and failed components, however all worked fine with a substitute fast switching rectifying diode.

                      Another fantastic TV saved from landfill!

                        Comment

                        • tom66
                          EVs Rule
                          • Apr 2011
                          • 32560
                          • UK
                          #7
                          Re: Panasonic TH-P42X30A no standby 5 volt

                          Nice. These are good sets, shame they don't use good caps on the PSU though.
                          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

                            Previous template Next

                            Related Topics

                            Collapse
                            • tvguy12012012120
                              Zombie Samsung UN55NU6900F dead / no standby voltage - randomly came to life after hours of troubleshooting then died
                              by tvguy12012012120
                              This is my first attempt at troubleshooting a board like this, I know I could just buy a new board but I'm curious to figure out how this works. I've been testing different components in the evenings this week and I think the problem is with the IC failing to start up for some reason. When the board is plugged in there is no standby voltage.

                              Then today it randomly sprung to life like a zombie but shortly died thereafter. I have no idea why it would have done that and its the first time I've seen it running. I discharged capacitors on the board last night, then it was sitting today....
                              02-07-2025, 05:13 PM
                            • BobbyMJ
                              Panasonic TC-P60S30 - no standby voltage
                              by BobbyMJ
                              Hi All,
                              Wanting to learn some electronics repair skills.
                              I found a non working Panasonic TC-P60S30 and this is my first project / attempt.

                              So far I have found a blown cap on the main power supply board.
                              After replacing it there's still no standby power.

                              Poked around and found a resistor on the PSUB power supply board that measures open.

                              An online resistor calculator shows this is a 93k ohm resister.

                              My questions:

                              Is that correct, 93k ohms?
                              Is it a fusible resistor?
                              Lastly, how do I know what wattage?...
                              05-14-2025, 06:42 PM
                            • sam_sam_sam
                              Panasonic switching power supply daughter board has two 27uf @ 50 volt capacitors which I do not keep in stock
                              by sam_sam_sam
                              I did not have any 27uf @ 50 volt capacitors but one nice thing is that it has enough room for two capacitors in parallel a 22uf and a 4.7uf @ 50 volts 22 plus 4.7 equals 26.7uf which so very close to 27uf I will show some pictures of it sometime tomorrow

                              This is one of the shit est boards I seen in a very long time and it was the daughter board the traces just lifting off the board I had to use the capacitor leads to repair the the traces and the main board is not any better because I had to repair several traces for the daughter board to the main board

                              After all of...
                              07-13-2024, 08:14 PM
                            • pcardoso73
                              iMac power supply short-circuit diode to ground
                              by pcardoso73
                              Hi,
                              I have an iMac with the power supply reference: ADP-200DFB.

                              This power supply is not working and when trying to debug the problem with a multimeter, I found what I thought to be a short circuited diode (the short-circuit is to ground).

                              With the continuity test it beeps both ways, so doesn't block current flow at all then reverse biased. But after removing the diode the beep continues and the diode seems healthy. It seems to exist a real short-circuit.

                              As I have another ADP-200DFB power supply (faulty one as well), I have checked the same...
                              06-09-2020, 08:47 AM
                            • Nevillet
                              Panasonic SA-PM71SD Micro HiFi - not comming out of standby
                              by Nevillet
                              Hi All,

                              I have the above mini HiFi that after powering displays the standby LED and when the power switch is pressed the relay momentarily clicks in then cuts out again.

                              I've included an image of the power board schematic.



                              There is 5.9V present on pin 4 of CN507 and when the standby button is pressed 2.6V momentarily appears on pin2 of the same connector.

                              Any thoughts would be welcome.



                              The service manual exceeds the Badcaps file size limit but it can be found here:...
                              08-24-2023, 10:58 AM
                            • Loading...
                            • No more items.
                            Working...