Announcement

Collapse
No announcement yet.

Vizio M65-C1 - No Power

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Vizio M65-C1 - No Power

    Hey guys. I have a 65" Vizio M65-C1 UHD 4K TV that has no power. I've done a lot of research on this model and some common problems that other people seem to have is unfortunately not applicable to me and my TV as I have different symptoms. I've documented all of my measurements and behavior I've noticed as follows:

    Symptoms:

    1. TV does not power on.
    2. Power light in bottom right corner (if facing display) briefly lights for a moment upon plugging in power and fades to black. No response from power button or remote control.
    3. Purple/Red LED located on the main board does nothing at any point. (I understand it's supposed to flash and then remain solid if working properly. Mine does nothing at all.)

    Below are the measurements I have taken. The first set is connected but powered OFF and the second set of measurements is while powered ON:

    Code:
    --------------------------------------------------------------------------
    
    Measurements taken with only main board, power board, power button board, and 
    power LED indicator connected [B][U]while OFF:[/U][/B]
    [B][U]
    CN9101[/U][/B]
       [B][U]Pin Marking[/U][/B]           [B][U]Measurement Taken[/U][/B]
    1. +5V/3.5V                     5.08V
    2. +12V                        19.05v
    5. +12V                        19.05v
    7. +12V_A                      19.05v
    9. GND
    11. GND
    13. 3D                         0
    15. ON/OFF                   39-42mV (fluctuating)
    
    [B][U]CN9102[/U][/B]
     [B][U]Pin Marking[/U][/B]          [B][U]Measurement Taken[/U][/B]
    2. +5V/3.5                      5.08V
    4. +12V                       19.05V
    6. +12V                       19.05V
    8. +12V_A                      19.05V
    10. GND
    12. GND
    14. PS_ON                      76.1mV
    16. DIM                        8.9mV
    
    [B][U]CN9203[/U][/B]
     [B][U]Pin Marking[/U][/B]           [B][U]Measurement Taken[/U][/B]
    1. N/C 
    3. N/C
    5. GND
    7. GND
    9. N/C (but marked GND)
    11. +24V                         7mV
    13. +24V                         7mV
    
    [B][U]CN9201[/U][/B]
     [B][U]Pin Marking[/U][/B]           [B][U]Measurement Taken[/U][/B]
    2. N/C
    4. N/C
    6. GND
    8. GND
    10. N/C (but marked +24V)
    12. +24V                         7mV
    14. +24V                         7mV
    
    --------------------------------------------------------------------------
    Code:
    Measurements taken with only main board, power board, power button board, and
    power LED indicator connected [B][U]while ON:[/U][/B]
    [B][U]
    CN9101[/U][/B]
       [B][U]Pin Marking[/U][/B]          [B][U]Measurement Taken[/U][/B]
    1. +5V/3.5V                     5.08V
    2. +12V                        19.05v
    5. +12V                        19.05v
    7. +12V_A                      19.05v
    9. GND
    11. GND
    13. 3D                         0
    15. ON/OFF                     153mV (and drops slowly)
    
    [B][U]CN9102[/U][/B]
     [B][U]Pin Marking[/U][/B]            [B][U]Measurement Taken[/U][/B]
    2. +5V/3.5                      5.08V
    4. +12V                       19.05V
    6. +12V                       19.05V
    8. +12V_A                      19.05V
    10. GND
    12. GND
    14. PS_ON                      3.65V
    16. DIM                        3.33V
    
    [B][U]CN9203[/U][/B]
     [B][U]Pin Marking[/U][/B]            [B][U]Measurement Taken[/U][/B]
    1. N/C 
    3. N/C
    5. GND
    7. GND
    9. N/C (but marked GND)
    11. +24V                         24.26
    13. +24V                         24.26
    
    [B][U]CN9201[/U][/B]
     [B][U]Pin Marking[/U][/B]            [B][U]Measurement Taken[/U][/B]
    2. N/C
    4. N/C
    6. GND
    8. GND
    10. N/C (but marked +24V)
    12. +24V                         24.26V
    14. +24V                         24.26V
    
    -----------------------------------------------------------------------
    Something else I can add based on what I saw was asked in other threads based on this model is that the 3 large caps (C9804, C9805, and C9823) read 390.4V

    I did come across this YouTube video where a guy had a problem with a resistor and a diode located on the power board and changing them fixed his problem.

    The video is based on the symptoms of the 19V line fluctuating/not steady and a flashing purple light on the main board. I don't share either of those symptoms, but I went ahead and checked the two components anyway.

    The resistor on the bottom of my power board R9114 is reading in the ~1 mega ohms range just like his was in the video while the one above it R9135 is reading as his does about 8.9 kilo ohms. Should I change this resistor? R9114? It reads the same as the guy's does in the video and he changed it. Apparently R9114 is supposed to read about 8.9 kilo ohms like R9135 does.

    The diode marked D9103 checked out ok, passing voltage one way but not the other.

    That's really all that I can tell you about the TV. While I'm not a complete newb, I am still learning a lot about TV repair and with my limited knowledge I think it's a main board problem.

    I've already did some initial searching for the replacement board just to see if they are even available and it seems like there are a few on ebay, but if at all possible, I'd like to repair the component(s) that are at fault if it is indeed the main board. I haven't yet come across a thread/video where someone fixed a main board problem yet although I did see a thread that made a reference to reflowing the processor on the main board.

    Can someone take a look at what I've posted here and guide me on what I can do from here to repair this TV? I've attached pics, but let me know if you need more.

    Thanks
    Attached Files

    #2
    Re: Vizio M65-C1 - No Power

    ON/OFF signal (backlight on logic) not going high when turned on is a classic symptom of bad BGA connections on the main board. It should be at the same voltage as the PS_ON signal. Search your model and M43-C1. Should be lots of threads on the topic.
    Last edited by neilc6; 09-22-2020, 04:44 PM.

    Comment


      #3
      Re: Vizio M65-C1 - No Power

      Originally posted by neilc6 View Post
      ON/OFF signal (backlight on logic) not going high when turned on is a classic symptom of bad BGA connections on the main board. It should be at the same voltage as the PS_ON signal. Search your model and M43-C1. Should be lots of threads on the topic.
      Thanks for the reply.

      I went ahead and got the heatsink off of the mainboard which was a real pain, but I got it off and cleaned up the dried up thermal paste put on at the factory on both the main board chips and the heatsink.

      I am used to doing reflows on MacBook Pros, laptops, and game consoles, but haven't done one on a TV main board yet. I'm going to assume the process is the same. I have a hot air reflow station with preheater that I typically use and lots of good BGA flux and experienced with the process and reflow profile.\

      However, what I am not sure of is which chip am I supposed to be reflowing? There are two under the heat sink that look basically identical.

      Any advice? I have a hot air nozzle that fits for many different size BGA chips but it can only do one at a time, so I should probably do the one that needs it.

      I'm assuming one is the main processor and the other is some kind of SoC that runs the firmware/software for the "smart" aspects, but that is a complete guess. I have no idea what chip does what to be honest.

      I attached some pics. Can you give me some insight?

      Thanks again.

      (EDIT: Oh, and nevermind the gray markings around one of the chips. There was some heat resistant tape placed by Vizio over those memory chips and its just the residue left behind)
      Attached Files
      Last edited by grimacelord; 09-22-2020, 05:36 PM.

      Comment


        #4
        Re: Vizio M65-C1 - No Power

        If none of the threads on here have that info, I'd pick one and give it some heat for around a minute (around 120°) and see if it turns on.

        Comment


          #5
          Re: Vizio M65-C1 - No Power

          Originally posted by diif View Post
          If none of the threads on here have that info, I'd pick one and give it some heat for around a minute (around 120°) and see if it turns on.
          Yeah, I sort of figured it might come to just guessing. I doubt there is tons of info on in-house chips made by and for Vizio.

          I decided that if I must choose which chip to reflow, then it seems logical to choose the one that Vizio placed heat resistant tape around, agreed? They made an attempt to better thermally protect that chip for some reason, so I am assuming it's because it's the one most likely to have faults appear in the BGA due to heat/cooling expanding and contracting solder balls.

          Does that seem like a good pick for you?

          Comment


            #6
            Re: Vizio M65-C1 - No Power

            If reflowing doesn't work out, looks like I found a pre-balled replacement chip for one them on eBay.

            https://www.ebay.com/itm/274372446167

            Comment


              #7
              Re: Vizio M65-C1 - No Power

              So which one is it? Top or bottom as per your photo?

              Comment


                #8
                Re: Vizio M65-C1 - No Power

                Pic 2 of 3 is the "top chip" (the one that Vizio had thermal tape around the memory chips)

                Pic 3 of 3 is the bottom chip.

                The ebay listing I linked to is the bottom chip. I tried, briefly, to source the top chip but was only led down a rabbit hole of alleged Hong Kong suppliers and never actually found one to purchase

                Comment


                  #9
                  Re: Vizio M65-C1 - No Power

                  Which one made the TV come on after you gave it a hit of heat?

                  Comment


                    #10
                    Re: Vizio M65-C1 - No Power

                    Originally posted by diif View Post
                    Which one made the TV come on after you gave it a hit of heat?
                    Haven't performed the reflow yet. Been doing some studying up on it to see if the technique differs from a standard reflow profile I typically use for game consoles or laptop computers where the GPU overheated and failed.

                    I'll be doing it shortly today and I will be sure to post the results. I think I am going to use the "top" chip as per my pic as the target.

                    We'll see what happens!

                    Comment


                      #11
                      Re: Vizio M65-C1 - No Power

                      Update: So I reflowed the "top" chip (marked VM50 8000A0-CFE3 / NRG562.00 ) and now the TV powers on! Hooray! However, the screen is split down the middle vertically. One half is black, the other half has some garbled distortion of lines/colors.

                      I'm going to keep messing with it and see what I can figure out here
                      Last edited by grimacelord; 09-23-2020, 09:33 AM.

                      Comment


                        #12
                        Re: Vizio M65-C1 - No Power

                        So messing around with it some more, if I disconnect either ribbon cable that is going down to the tcon? board, the entire screen remains black although I can see flashes of what I can only describe as "backlight flashing". Basically flashes of varying degrees of backlight, but all black screen. This happens if I remove either ribbon cable. Only when both are plugged in do I get a partial, although distorted, image on the screen.

                        I attached a pic to show it. I have the TV face down on a table, so this is the overhang and photo taken from below.

                        So I guess the question is, do I reflow the other chip or is this a TCON or even a panel problem?
                        Attached Files

                        Comment


                          #13
                          Re: Vizio M65-C1 - No Power

                          Another update. So in my last post, I showed how half the screen was black and the other half was distorted garbled mess.

                          So I took the TCON board out and checked it's fuse - it was OK. I checked some caps to see if any were short to ground. They weren't. I looked under the microscope to see if any resistors blew - they didn't appear to. So I decided to clean all of the connectors with some iso alcohol and then reinstalled the TCON.

                          Also, in my previous image, I didn't have the heatsink fully installed to the main board. I just had it loosely connected to test and see if it worked before going through the rather painful process of resoldering the heatsink on only to have to take it right back off.

                          Well, I went ahead and fully installed the heatsink including all thermal pads on the bottom, etc. Now, I don't get the line down the screen. I can see an image, but the images (such as the menu) is flashing around so rapidly, it's all over the place. It's not a steady image.

                          I took two pictures and a video to show what I mean. I converted the video to gif so I can post it here and not bother with YouTube. I had to make it small enough to be within requirements to post. Again, the images are taken from underneath, as I have the TV face down on a table. So what you are seeing is the edges of the TV hanging off the side of the table and taken from underneath. Attached are those images.

                          So I don't know if it was messing around with the TCON board or installing the heatsink that improved the image, so I am still where I was.

                          I don't know if I am dealing with a TCON problem or if it's still the mainboard causing the distortion I'm seeing. There is still that other chip that I haven't reflowed. Not sure if I should.
                          Attached Files

                          Comment


                            #14
                            Re: Vizio M65-C1 - No Power

                            Rather than reflow give it 120c for a minute. Nothing melts but it should expand enough to work and give a clue as if you are in the right place.

                            Comment


                              #15
                              Re: Vizio M65-C1 - No Power

                              So as another update, I did what you suggested and hit the other chip with 120C for about a minute and tried again. No change.

                              I then went on and reflowed it. No change.

                              I started messing with the main board by pressing down on the heatsink at different locations and by doing so, it did seem to affect the display.

                              I'm starting to believe that the main board was just so damaged, reflowing alone isn't going to fix it. It probably needs reballing altogether or at worst, replacement.

                              Comment


                                #16
                                Re: Vizio M65-C1 - No Power

                                You will need to reflow that first chip again. Must have not hit proper temps for proper flow.

                                Comment


                                  #17
                                  Re: Vizio M65-C1 - No Power

                                  @grimacelord did you have any luck reflowing that first chip again? I'm working on a similar issue.

                                  Comment


                                    #18
                                    Re: Vizio M65-C1 - No Power

                                    Those boards have BIG problem with overheating, I would just get new board and sell TV...

                                    Comment

                                    Working...
                                    X