Looking for schematic for Vizio M75-C1 or similar

[jimmyboy111]

anything M with C1 at the end would work giving some hints

.. it looks like another motherboard yet again .. did reflow with rework gun and very little changed .. the bottom processor turns on but the top one only at random along with the T-con and no backlights .. also looked at the buck converters and regulators on the mainboard .. they look to have normal voltages .. the white power light on the bottom corner flickers at random .. sometimes it turns on sometimes not when I cycle the AC supply

.. next ESR on caps and look for shorted MLCC's .. not having a schem or reference voltages is so irritating .. I should prob check Norcal

.. the power boards supply their normal voltages except the power to the t-con and backlights .. all controlled by the mainboard .. cannot find the ps-on trigger for those two supplies .. will have to pull it and look closer

[Storyteller12]

Re: Looking for schematic for Vizio M75-C1 or similar

It’s the mainboard BGA chip. I’ve never had a different problem with the Vizio M series.
Sometimes reflow doesn’t work or the previous owners try to bake them in the oven and mess something up.

Try reflowing again. Did you remove heatsinks?

[jimmyboy111]

Re: Looking for schematic for Vizio M75-C1 or similar

yes i did that .. after more messing with it the backlight and t-con voltages do fire up every second restart so all the voltages and supplies are working but I dont even see a flicker on the screen under a strong lamp .. the voltages all pop up and the bottom corner white power light starts and nada

.. I removed the heat sink all the thermal compound and cleaned the chips and reflowed again .. decided to go a little hotter 440degF about two minutes and still the same thing

.. at this point I am on the fence if it still a BGA problem after reflowing 3x and may start inspecting each chip and cap on the mainboard and start checking signals with the scope

.. people try to bake it? there are plastic connectors all over the edge that would destroy it for sure

[Storyteller12]

Re: Looking for schematic for Vizio M75-C1 or similar

440f isn’t hot enough to reflow. Solder doesn’t melt at 440. Also if you got the backlights to work indicates the BGA chip is the problem

[diif]

Re: Looking for schematic for Vizio M75-C1 or similar

Lead free solder melts at around 218c/424F.
However you need to set the heat on your hot air station much higher due to the surrounding air being cold and the board absorbing heat also.
Are you using flux ?