Vizio M65-C1

[mrtek]

This is a better image of the component in question

[howardc64]

Hi All
I was able to revive the main board by removing the huge heat sink and reflow the 2 CPUs. Now the On/OFF signal to power supply is at 3.3V when the power button is pressed. The backlights are turning on but no image on the screen. I figured out the there is no 12V on either side of the FUSE on the T-Con board. This voltage comes from the main board. No shorts on the main board for 12 V but it looks like the voltage is generated by this IC U713 on the back side (Q503 5383A are the markings on the IC). The output of this IC, is exactly where the Ref. Des. U703 is located in the image and is directly connected to the 12V going to the T-Con board. Can't find the spec sheet.
Did anybody ever find this issue? Also I suspect that the location circled in green still has a missing component.

Thank you again for your help.

Massimo

Describe your reflow process. I've not seen any non professional process (pro = SOC removal, reball, resolder with reflow station) last and depending on method, temperature, and duration, its possible not even all the SOC balls have been reconnected. I have used toaster oven to bake several of these boards and achieve complete revival but failed not too long after.

The reason rebaking reflows don't work is because once SOC solder balls crack, the cracked surface gets oxidized. Rebake just reconnect around the oxidization poorly but eventually fails again. I posted a few years ago links to online diagnostic microscope pictures on rebake only type of reflow.

[mrtek]

Hi all again.

I was able to generate the 12V for the T-Con on the main board. I was able to find a datasheet for the mysterious IC listed above 5358A.The actual part is G5358A ( High Efficiency 4A Synchronous Buck Converter )
made by some company in Asia. See attached datasheet.( ) It appears that on the main board there is the same regulator producing 5V.(input is 19V from PS) According to the datasheet, there is EN pin (#5). This pin is connected to the CPU by one resistor (16.5K) on the other side of the board. I placed the same resistor on location R7018 This connection enabled the 12V regulator that feeds the T-CON. The 12V regulator, using the same 19V from PS, is configured differently to produce the 12V. After that the TV turned ON and the Vizio logo showed up on the screen among the NO SIGNAL post on it. I did not have the time to put everything back together but I need to find a way to mount a fan on the back cover to cool off the huge heat sink.

[mrtek]

Describe your reflow process. I've not seen any non professional process (pro = SOC removal, reball, resolder with reflow station) last and depending on method, temperature, and duration, its possible not even all the SOC balls have been reconnected. I have used toaster oven to bake several of these boards and achieve complete revival but failed not too long after.

The reason rebaking reflows don't work is because once SOC solder balls crack, the cracked surface gets oxidized. Rebake just reconnect around the oxidization poorly but eventually fails again. I posted a few years ago links to online diagnostic microscope pictures on rebake only type of reflow.

I did have already a hot air reflow station and I purchased a large nozzle . I have read , on some post what temperature was used to reflow the same kind of CPU after the heat sink was removed. Used some liquid flux on the 4 side of each CPU and set the temp at 350F. For a couple of minutes I kept the nozzle at about 2 inches. After 2 minutes I brought the nozzle closer to about 1 in for 3-4 minutes. After that I brought it back up to 2 inches for a total of 8-9 minutes. That seemed to do the trick. I understand it maybe not be a final / permanent solution, but for now I proved that no other component is faulty. I did purchased another main board from a vendor and that was faulty as well where the oN/OFF signal was low all the time and did not work for me. I was able to get my money back even when the vendor was telling me that the problem was " DEEPER".

[howardc64]

I did have already a hot air reflow station and I purchased a large nozzle . I have read , on some post what temperature was used to reflow the same kind of CPU after the heat sink was removed. Used some liquid flux on the 4 side of each CPU and set the temp at 350F. For a couple of minutes I kept the nozzle at about 2 inches. After 2 minutes I brought the nozzle closer to about 1 in for 3-4 minutes. After that I brought it back up to 2 inches for a total of 8-9 minutes. That seemed to do the trick. I understand it maybe not be a final / permanent solution, but for now I proved that no other component is faulty. I did purchased another main board from a vendor and that was faulty as well where the oN/OFF signal was low all the time and did not work for me. I was able to get my money back even when the vendor was telling me that the problem was " DEEPER".

hot air station with square nozzle + side added flux definitely helps. Usually a bottom heater is also necessary to prevent board warpage to avoid damage as well as planer for all the BGA balls to contact. But any oxidized cracked BGA solder balls will still be there embedded in the reflowed balls ready to crack again eventually