Vizio M43-C1 No Backlights

[dsant90]

Just to add that for the D55u-d1, I only did it to one CPU, not two

[ziddey]

Has a main board part interchange ever been determined? Just picked up an m50-c1 that needs a new board. Bad board is gxfcb0qk012040x / 715g7288-m02-000-005t.

Found https://www.tvpartstoday.com/756TXFC...fcb0qk0120.htm which lists "756TXFCB0QK0120 Vizio Main Board, 756TXFCB0QK012, 715G7288-M02-000-005T, GXFCB0QK012040X, GXFCB0QK012030X, GXFCB0QK012020X, CBPFETEKX6C, M50-C1"

I do see that the d50u-d1's gxfcb0qk0220030x is much cheaper and more readily available. Looks like a similar board, but the picture shows the cn210 connector is populated on this model.

edit: shopjimmy states "PLEASE NOTE: The main board you receive may or may not have connectors at locations CN210, CN212 and CN203. These connectors are not used in model M50-C1 and will not affect functionality. "

[alfatv]

I can see that D50u-D1 has much better heatsink construction and I think springs are used to hold it down. Basically the springs should provide even pressure between heatsink and chips and maintain it even if board is flexing.
I thought about this previously and modified M43-C1 heatsink. I removed all pins and put 4 M2 screws/nuts and springs in between. This has been running for 2-3 months, will see how long it will last.
At least seeing these D50u-D1 boards available means that they don't fail as badly as M's.

[ziddey]

While looking for a replacement board, I threw the old one in the oven.

Preheated to 425'f, and then tossed it in. Cut the heat after 6 minutes, and cracked the door after 10. Waited half an hour (way too little time) and gave it a go. Guess the tv works for now...

[ziddey]

Just realized the coax soldered itself shut in the oven.



Got it opened back up, but not without completely melting and making a mess of the plastic insulation. Seems to be working now though..


Might not be a bad idea to stick a paper clip or similar in the coax port before putting it in the oven. It'd be a lot easier to desolder that than to try and clean out the port otherwise. Maybe it'd have been possible to flow out working from the inside, but I didn't feel like taking the tv apart again.

[pokey1kenobi]

Hoping someone can help me find the value of, or hook me up with the smd ceramic capacitor on the back of the main board at position C478 (backside/middle of board). I knocked it off and lost it after removing the heat sink on XFCB0QK003020Q.

[johnboiles]

Originally Posted by johnboiles

My simple heatsink-on toaster reflow from mid December is still working fine! I'm truly surprised! If you don't have the skill or tools to get the soldered-on heat sink off, just try a toaster reflow with it on first!

It finally just died this week. I'd say ~8 months is pretty great for a janky toaster oven fix!! I tried it in the oven again with a slightly more aggressive profile (below) and it's back to life again.

200F preheat 6 min
350F for 3.5 min
450F for 4 min

That replacement board I got didn't work. Not sure if it's DOA or if it's not the right one. I for sure should have tested it when it arrived but it never felt worth it to take the tv apart when it was working I did try to toast it too but not getting anything from it -- not even the power LED on the TV comes on.

[johnboiles]

I kept trying more aggressive profiles until the connectors started melting. Each time the TV would come back to life for a few hours then die. I kinda wonder if the thermal grease on the heatsink stopped working after being in the toaster so many times.

I then tried a more proper reflow: I chopped off the heatsink and tried a reflow with my hot air SMD station, but I busted an inductor along the way. Nothing happens now with the original main board. I'm throwing in the towel and bought a TCL 635.

Overall I'm happy that the toaster oven thing gave 8 months of extra life on the TV. It meant I got to get a 2021 model TV instead of a 2020 (though TVs are super expensive right now with the chip shortage).

Thanks everyone for their ideas and camaraderie! Good luck fixing your TVs!

[howardc64]

Saved another one with reflow oven 375F(laser temp gun shows board slightly hotter)/8min. This time a P502UI-B1E (2nd one repair by this method). circa 2015 50" Vizio UHD.

Checked PSU and got 12V (standby voltage on this model) and saw PS_ON trigger with power on. Then onto Betty Crocker. Works again for the time being. Toaster oven is batting 4 for 4 so far. 3 Vizio TVs with main boards of this general design and a Nintendo Switch. TVs gets pretty light use and Switch probably gets the most use and still going after 8-9mo.

On these Vizio main boards, I think its really important to remove the heat sink but it is crazy hard without the right tools. What I use is

- Hakko FR-301 powered suction desoldering tool on fairly high temp
- Soldering gun (ex Weller D-650)

2 people, 4 hands, 2 heating devices, lower post melting temp with leaded solder (low melt solder probably even better). If we had a bigger opening diameter tip for the Hakko to go completely around the heat sink post, might have been able do the job alone. Standard tips don't wrap around this big posts.

I also found the thermal paste completely dried and hardened on this one. Took while to even get it off.. hardest I've ever seen. So part of the repair longevity is probably fresh thermal paste which is only possible with heat sink removal.

Not saying this is the proper fix but prob best most DIYer can do without access to BGA reflow station.

[pokey1kenobi]

Originally Posted by howardc64

Saved another one with reflow oven 375F(laser temp gun shows board slightly hotter)/8min. This time a P502UI-B1E (2nd one repair by this method). circa 2015 50" Vizio UHD.

Checked PSU and got 12V (standby voltage on this model) and saw PS_ON trigger with power on. Then onto Betty Crocker. Works again for the time being. Toaster oven is batting 4 for 4 so far. 3 Vizio TVs with main boards of this general design and a Nintendo Switch. TVs gets pretty light use and Switch probably gets the most use and still going after 8-9mo.

On these Vizio main boards, I think its really important to remove the heat sink but it is crazy hard without the right tools. What I use is

- Hakko FR-301 powered suction desoldering tool on fairly high temp
- Soldering gun (ex Weller D-650)

2 people, 4 hands, 2 heating devices, lower post melting temp with leaded solder (low melt solder probably even better). If we had a bigger opening diameter tip for the Hakko to go completely around the heat sink post, might have been able do the job alone. Standard tips don't wrap around this big posts.

I also found the thermal paste completely dried and hardened on this one. Took while to even get it off.. hardest I've ever seen. So part of the repair longevity is probably fresh thermal paste which is only possible with heat sink removal.

Not saying this is the proper fix but prob best most DIYer can do without access to BGA reflow station.

Hey, good times I'd like to know if you replaced the heat sink and if you had any advice if so. After replacing mine w/fresh paste it wouldn't fire up until I removed it again. I noticed, felt rather, an electrical buzz when touching the heat sink while plugged but refusing to turn-over. I suspect a layer of copper in the board was in contact with the metal standoffs of the sink and shorting out. My collection of computer parts has me very close to finding a better cooling solution but one thing or another(12v+, way to mount cooler, size limitations, etc...) I'll add the pics I've taken along the way to get some cells firing on the thread to help others. And any suggestions are welcome.. Cheers

[howardc64]

Originally Posted by pokey1kenobi

Hey, good times I'd like to know if you replaced the heat sink and if you had any advice if so. After replacing mine w/fresh paste it wouldn't fire up until I removed it again. I noticed, felt rather, an electrical buzz when touching the heat sink while plugged but refusing to turn-over. I suspect a layer of copper in the board was in contact with the metal standoffs of the sink and shorting out. My collection of computer parts has me very close to finding a better cooling solution but one thing or another(12v+, way to mount cooler, size limitations, etc...) I'll add the pics I've taken along the way to get some cells firing on the thread to help others. And any suggestions are welcome.. Cheers

Not sure what is happening on your board. Loose parts etc.

I tried some small fans with original heat sink but it didn't move much air at reasonably low audible RPMs. Also can't mount it to provide good cooling. The original heat sink don't have much room for any good solution.

But custom heat sinks need to have secure contact to the chip surface and original heat sink mounting holes aren't perfect for the job. A combined custom heat sink such as you are attempting might provide a solution.

Sorry but I gave up on forced air cooling after a brief attempt.

[pokey1kenobi]

I'm currently looking at making adjustable threaded plastic stand-offs to avoid whatever v+ continuity I had with the metal ones preventing the tv from booting. This will allow me to use the best cooling solution I have atm, the Asus fan blowing between the HS and the board. BUT, it's a 12v fan and I'd like to use a switched 12v point on the board, if there is one. maybe howardc64 could advise of a spot on M43 board or unit that has switched 12V.

A waterblock would likely be the best one could hope for, I'm sure alibaba or Banggood type places would have an afordable option. Might even really add longevity after a good reflow.

Also, when using flux and trying to get it under the chips, only apply on 3 sides to avoid a vaper lockout thing. As advised by knowledgeable youtuber..

[victor_pv]

Originally Posted by howardc64

These boards popcorn really easily with heat gun if don't bake it at 100C for a couple of hours in advance to get the moisture out.

I have much better luck recently with 10min bake at 375C in a toaster oven. Fixed 2 of these boards (various Vizio TVs all with same basic board design) I did remove the heat sink, cleaned off thermal paste and removed all thermal rubber during the baking process.

We'll see how long it last but so far batting better than my heat gun/hot air station repair that can easily popcorn these boards.

BTW, took temp readings on the heat sink while TV is running. The 2 BGA chip area are about 120-125F and the whole board is between 90-110F since the large heat sink radiates all over. The thermal cycling is probably what is killing the 2 BGA's large 2D solder ball grid contracts.

Thanks for the advise on this.
I just reflowed one of these board in a toaster/reflow oven with a controller I built a while back to reflow small prototype boards, and the TV has been running for a couple of days now, will see how long it lasts.
I heated the board to 50C for a minute, then ramped up to about 170C, another couple of minutes to get there, when raised up to 190C, but because thermal inertia the temperature on the board continued going up and got up to about 210C at the heatsink, stayed there for a minute or so and started going down slowly.

My controller uses a thermocouple I normally just keep close to the PCB, but in this case since I didn't remove the soldered heatsink, only the rubber pads on both sides.
I put the thermocouple in a hole the heatsink had, hopefully to ensure the reading would match the temp at the ICs closely.

Posting in case it helps anyone reading this thread.

[howardc64]

Originally Posted by victor_pv

Thanks for the advise on this.
I just reflowed one of these board in a toaster/reflow oven with a controller I built a while back to reflow small prototype boards, and the TV has been running for a couple of days now, will see how long it lasts.
I heated the board to 50C for a minute, then ramped up to about 170C, another couple of minutes to get there, when raised up to 190C, but because thermal inertia the temperature on the board continued going up and got up to about 210C at the heatsink, stayed there for a minute or so and started going down slowly.

My controller uses a thermocouple I normally just keep close to the PCB, but in this case since I didn't remove the soldered heatsink, only the rubber pads on both sides.
I put the thermocouple in a hole the heatsink had, hopefully to ensure the reading would match the temp at the ICs closely.

Posting in case it helps anyone reading this thread.

Thanks for the update. Got some longevity over reflow repair info now with a little more use on 2 of these VIZIO boards with similar design (reflowed with heat sink removed) and an LG with no heat sink. Looks like fix doesn't really last. Probably the ball cracks already got oxidized. Anyway looks like $500+ BGA reflow workstation is necessary for long term fix.

[ziddey]

Originally Posted by ziddey

Has a main board part interchange ever been determined? Just picked up an m50-c1 that needs a new board. Bad board is gxfcb0qk012040x / 715g7288-m02-000-005t.

Found https://www.tvpartstoday.com/756TXFC...fcb0qk0120.htm which lists "756TXFCB0QK0120 Vizio Main Board, 756TXFCB0QK012, 715G7288-M02-000-005T, GXFCB0QK012040X, GXFCB0QK012030X, GXFCB0QK012020X, CBPFETEKX6C, M50-C1"

I do see that the d50u-d1's gxfcb0qk0220030x is much cheaper and more readily available. Looks like a similar board, but the picture shows the cn210 connector is populated on this model.

edit: shopjimmy states "PLEASE NOTE: The main board you receive may or may not have connectors at locations CN210, CN212 and CN203. These connectors are not used in model M50-C1 and will not affect functionality. "

Updating on this.

The oven treatment only worked for a few months, and I ended up giving this part a shot. Received GXFCB0QK012030X, which has two additional connectors compared to the original 12040x. Working well.

[neilc6]

Ebay seller kcrownie repairs this board now. I have used him before for Samsung F model year boards and some LG boards before with no issues.

[victor_pv]

Originally Posted by victor_pv

Thanks for the advise on this.
I just reflowed one of these board in a toaster/reflow oven with a controller I built a while back to reflow small prototype boards, and the TV has been running for a couple of days now, will see how long it lasts.
I heated the board to 50C for a minute, then ramped up to about 170C, another couple of minutes to get there, when raised up to 190C, but because thermal inertia the temperature on the board continued going up and got up to about 210C at the heatsink, stayed there for a minute or so and started going down slowly.

My controller uses a thermocouple I normally just keep close to the PCB, but in this case since I didn't remove the soldered heatsink, only the rubber pads on both sides.
I put the thermocouple in a hole the heatsink had, hopefully to ensure the reading would match the temp at the ICs closely.

Posting in case it helps anyone reading this thread.

It's been a couple of months since I reflowed that board, and gave the TV to a friend that uses it about daily. So far it's working fine.

[gte577j]

Just to add a data point: My M43-C1 had this same issue, and I replaced it with a D50u-D1 main board and it works perfectly; no modifications needed.