Toshiba 42HP66 - Pulsing -Vy

Collapse
X
 
  • Time
  • Show
Clear All
new posts
  • capkid
    Badcaps Legend
    • Oct 2010
    • 1339
    • United States

    #1

    Toshiba 42HP66 - Pulsing -Vy

    I sold this TV to a friend over a year ago after replacing the IPMs and fuses, and it now has sound and no picture again. The voltages check out, except for the -Vy, which pulses between -1V and -2V. The pulsing is audible. I disconnected the Y-buffer from the Y-Sus, but the pulsing is still there. It's most likely a Y-Sus issue, and I could probably find the culprit, but I don't have a whole of time to spend on this TV. Has anyone experienced this issue? What was the resolution?

    Y-Sus part number is 6871QYH053B.

    Thanks
    LG Plasma Mal-Discharge Correction Service
  • Alastair E
    Chief Womble
    • Mar 2013
    • 1963
    • U.K.

    #2
    Re: Toshiba 42HP66 - Pulsing -Vy

    With the reputation these LG based sets have--Its likely the IPM has failed again, loading down the -Vy
    Sadly, IPM's dont always fail the same way, making diagnosis sometimes--Stressful!
    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

    • capkid
      Badcaps Legend
      • Oct 2010
      • 1339
      • United States

      #3
      Re: Toshiba 42HP66 - Pulsing -Vy

      Yeah, I was thinking the IPM may have failed again. Neither of the fuses on the Y-Sus is blown, so I was hoping this might be a quick and cheaper fix.
      LG Plasma Mal-Discharge Correction Service

      Comment

      • capkid
        Badcaps Legend
        • Oct 2010
        • 1339
        • United States

        #4
        Re: Toshiba 42HP66 - Pulsing -Vy

        Well, it looks I have a shorted mosfet (IRFP4232), so I'm going to replace it and the other two that are chained to it.
        Attached Files
        Last edited by capkid; 04-27-2014, 09:41 PM.
        LG Plasma Mal-Discharge Correction Service

        Comment

        • capkid
          Badcaps Legend
          • Oct 2010
          • 1339
          • United States

          #5
          Re: Toshiba 42HP66 - Pulsing -Vy

          I replaced the three IRFP4232 mosfets, and I now have a whitewashed picture. The -Vy is reading -243V I guess I have more work to do. Crap.
          LG Plasma Mal-Discharge Correction Service

          Comment

          • tom66
            EVs Rule
            • Apr 2011
            • 32560
            • UK

            #6
            Re: Toshiba 42HP66 - Pulsing -Vy

            Have you tried adjusting -Vy down?
            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

            • capkid
              Badcaps Legend
              • Oct 2010
              • 1339
              • United States

              #7
              Re: Toshiba 42HP66 - Pulsing -Vy

              I turned the pot, but the voltage didn't budge. I may look at the card on which the pot is installed.
              LG Plasma Mal-Discharge Correction Service

              Comment

              • Ltank
                Badcaps Veteran
                • Jun 2013
                • 776
                • USA

                #8
                Re: Toshiba 42HP66 - Pulsing -Vy

                Sometimes the problems are simple, but is the pot good? With the power off have you varied the pot a bunch of times to clean it or sprayed cleaner to maybe clean the wiper? I myself sometimes dig too deep for a problem when it's right in front of me staring me in the face!

                Comment

                • capkid
                  Badcaps Legend
                  • Oct 2010
                  • 1339
                  • United States

                  #9
                  Re: Toshiba 42HP66 - Pulsing -Vy

                  The pot appears to be good; I'll take a closer look tonight. My line of thought is on par with your thinking. My first thought was to not dig too deeply into this issue and start removing and testing a bunch of components, since replacing the fets yielded a result that's close to what's expected. Several years of damaged boards and components from hacking around have made me a little wiser
                  LG Plasma Mal-Discharge Correction Service

                  Comment

                  • Shinju
                    Badcaps Legend
                    • Mar 2014
                    • 1239
                    • USA

                    #10
                    Re: Toshiba 42HP66 - Pulsing -Vy

                    I have one of these sitting in the Garage, not sure I want to deal with it if they fail even after replacing parts.

                    Its a 720p how is the quality of it picture wise?

                    Comment

                    • capkid
                      Badcaps Legend
                      • Oct 2010
                      • 1339
                      • United States

                      #11
                      Re: Toshiba 42HP66 - Pulsing -Vy

                      The picture isn't bad. I responded to your thread regarding the IPMs. The problem with these TVs is that the typical failure points (IPMs) can be expensive to remedy. IPMs cost around $40 each, and it's recommended that the Y-Sus and Z-Sus IPMs be changed at the same time. The fact that this TV failed again after one year is disappointing. Fortunately, I live near the plasmafix.com shop, so I got the replacement mosfets quickly and cheaply.
                      LG Plasma Mal-Discharge Correction Service

                      Comment

                      • Shinju
                        Badcaps Legend
                        • Mar 2014
                        • 1239
                        • USA

                        #12
                        Re: Toshiba 42HP66 - Pulsing -Vy

                        Nice, you and I are pretty close. I got a Vizio that is also giving me some hell too.

                        Thank you for the response in my thread, I will check into it!

                        Comment

                        • capkid
                          Badcaps Legend
                          • Oct 2010
                          • 1339
                          • United States

                          #13
                          Re: Toshiba 42HP66 - Pulsing -Vy

                          Oh, yeah, you're in Kirkland. Cool. Hopefully, you can get things figured out.
                          LG Plasma Mal-Discharge Correction Service

                          Comment

                          • capkid
                            Badcaps Legend
                            • Oct 2010
                            • 1339
                            • United States

                            #14
                            Re: Toshiba 42HP66 - Pulsing -Vy

                            Well, it looks like the -Vy pot is fine. I measured voltages on that card, and the transformer reads 185V on the primary and is converted to -220V. I'm wondering if I have a cap issue on the secondary side of that transformer. More to come...
                            Attached Files
                            Last edited by capkid; 04-30-2014, 12:22 AM.
                            LG Plasma Mal-Discharge Correction Service

                            Comment

                            • capkid
                              Badcaps Legend
                              • Oct 2010
                              • 1339
                              • United States

                              #15
                              Re: Toshiba 42HP66 - Pulsing -Vy

                              I tested most of the components on the secondary side of PS101's transformer, and the only one that seemed a little suspect is the cap at C22.

                              C22: ESR = 60, but I'm skeptical because it appears to be in parallel with a R21. The resistance across C22 is 10K ohms, which is the same as the value of R21.

                              C29 is in circuit with the U21 (KIA431A), and I couldn't get a reading using the ESR Micro V4 or the Fluke 87-III.
                              Attached Files
                              LG Plasma Mal-Discharge Correction Service

                              Comment

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

                                #16
                                Re: Toshiba 42HP66 - Pulsing -Vy

                                There's a couple of 10uF 400V caps on the secondary side of that board--If you have them, worth replacing while board is out, although I suspect this wont actually cure the problem, seeing the output is present....

                                The ESR of these high-voltage low value electrolytics should be below 3 ohms, IME....
                                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

                                • capkid
                                  Badcaps Legend
                                  • Oct 2010
                                  • 1339
                                  • United States

                                  #17
                                  Re: Toshiba 42HP66 - Pulsing -Vy

                                  I may have to pull them to check, since the two on the secondary side of the transformer are in parallel - getting 2.6 ohms. The cap on the primary side is 3.6 ohms, so I may change it to prevent a future failure. I'm thinking one of The SMD caps or the regulator is bad. Do you know the values of the SMD caps?
                                  LG Plasma Mal-Discharge Correction Service

                                  Comment

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

                                    #18
                                    Re: Toshiba 42HP66 - Pulsing -Vy

                                    Unfortunately--no, I dont know their values.

                                    IF they are the ones across the electrolytics, they'll be pretty small values seeing they are subject to the high voltages....

                                    The Datasheet for the regulator should indicate roughly what they are...
                                    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

                                    • capkid
                                      Badcaps Legend
                                      • Oct 2010
                                      • 1339
                                      • United States

                                      #19
                                      Re: Toshiba 42HP66 - Pulsing -Vy

                                      Ok. I removed the 10uF 400V caps from the board. The capacitance of each cap is just about right on spec, but the ESR is a bit off.

                                      Secondary side caps: 4.9 ohms and 3.5 ohms
                                      Primary side cap: 3.0 ohms
                                      LG Plasma Mal-Discharge Correction Service

                                      Comment

                                      • capkid
                                        Badcaps Legend
                                        • Oct 2010
                                        • 1339
                                        • United States

                                        #20
                                        Re: Toshiba 42HP66 - Pulsing -Vy

                                        The 400V caps seem fine. I found this diagram that appears to have the C22 cap circled that I mentioned earlier. Of course, the cap's values aren't listed. I measured the cap in the same location on the PS102 board with it still installed, and it measures 0.22uF and 24.5 ohms ESR. From what I can tell, the PS101 cap is physically smaller - I got 0.11uF when I measured it.

                                        http://obrazki.elektroda.pl/8808509600_1323159379.jpg

                                        http://www.elektroda.pl/rtvforum/topic2153162.html
                                        Attached Files
                                        Last edited by capkid; 05-04-2014, 11:26 AM.
                                        LG Plasma Mal-Discharge Correction Service

                                        Comment

                                        Related Topics

                                        Collapse

                                        • Document Archive
                                          Toshiba Satellite Pro C660-1NQ Specification for Upgrade or Repair
                                          by Document Archive
                                          This specification for the Toshiba Satellite Pro C660-1NQ can be useful for upgrading or repairing a laptop that is not working. As a community we are working through our specifications to add valuable data like the C660-1NQ boardview and C660-1NQ schematic. Our users have donated over 1 million documents which are being added to the site. This page will be updated soon with additional information. Alternatively you can request additional help from our users directly on the relevant badcaps forum. Please note that we offer no warranties that any specification, datasheet, or download for Toshiba...
                                          09-06-2024, 05:27 AM
                                        • Document Archive
                                          Toshiba Satellite L655-19C Notebook Specification for Upgrade or Repair
                                          by Document Archive
                                          This specification for the Toshiba Satellite L655-19C Notebook can be useful for upgrading or repairing a laptop that is not working. As a community we are working through our specifications to add valuable data like the L655-19C boardview and L655-19C schematic. Our users have donated over 1 million documents which are being added to the site. This page will be updated soon with additional information. Alternatively you can request additional help from our users directly on the relevant badcaps forum. Please note that we offer no warranties that any specification, datasheet, or download for Toshiba...
                                          09-06-2024, 05:59 AM
                                        • Document Archive
                                          Toshiba Satellite L655-1DJ Notebook Specification for Upgrade or Repair
                                          by Document Archive
                                          This specification for the Toshiba Satellite L655-1DJ Notebook can be useful for upgrading or repairing a laptop that is not working. As a community we are working through our specifications to add valuable data like the L655-1DJ boardview and L655-1DJ schematic. Our users have donated over 1 million documents which are being added to the site. This page will be updated soon with additional information. Alternatively you can request additional help from our users directly on the relevant badcaps forum. Please note that we offer no warranties that any specification, datasheet, or download for Toshiba...
                                          09-06-2024, 05:59 AM
                                        • Document Archive
                                          Toshiba Satellite L635-10K Notebook Specification for Upgrade or Repair
                                          by Document Archive
                                          This specification for the Toshiba Satellite L635-10K Notebook can be useful for upgrading or repairing a laptop that is not working. As a community we are working through our specifications to add valuable data like the L635-10K boardview and L635-10K schematic. Our users have donated over 1 million documents which are being added to the site. This page will be updated soon with additional information. Alternatively you can request additional help from our users directly on the relevant badcaps forum. Please note that we offer no warranties that any specification, datasheet, or download for Toshiba...
                                          09-06-2024, 05:59 AM
                                        • Document Archive
                                          Toshiba Portege Z30-C Notebook Specification for Upgrade or Repair
                                          by Document Archive
                                          This specification for the Toshiba Portege Z30-C Notebook can be useful for upgrading or repairing a laptop that is not working. As a community we are working through our specifications to add valuable data like the Z30-C boardview and Z30-C schematic. Our users have donated over 1 million documents which are being added to the site. This page will be updated soon with additional information. Alternatively you can request additional help from our users directly on the relevant badcaps forum. Please note that we offer no warranties that any specification, datasheet, or download for Toshiba Portege...
                                          09-06-2024, 05:33 AM
                                        • Loading...
                                        • No more items.
                                        Working...