Vizio M43-C1 No Backlights

[howardc64]

Re: Vizio M43-C1 No Backlights

Is your 12v rail still 18.9V ?

Yes, same as neilc6 on the first post.

[howardc64]

Re: Vizio M43-C1 No Backlights

UPDATE : TV working now with replacement main board

When first plugged in, main board LED light stays purple much longer while TV boot through the entire sequence before turning red (standby)

12V labeled rail on the PSU measures 19V even when TV booted into menu mode. Perhaps labeled wrong?

Main board heat sink gets hot quick. Plan to leave bottom input plate off and hook up 5V radial blower from China for $2 to keep it cooler.

[nomoresonys]

Re: Vizio M43-C1 No Backlights

Starting to think the label is wrong, glad to hear it's fixed, another one saved.

[howardc64]

Re: Vizio M43-C1 No Backlights

BTW, it seems later version main boards have a different BGA thermal contact design for the heat sink. Attached is board version 0250 (newer?) compared with 0030 (older?). Hard to tell from top down pic what the new design is. 0030 design is just 2 silver metal alloys impregnated in black anodized aluminum(?) heat sink with rubber heat transfer pad between BGA and heat sink.

Back of the TV in main board area gets really really hot on the plastic rear case where main board is even with short use. I guess Vizio didn't care about longevity here as even the dumbest testing (turn on for 10min haha) would have revealed this. Will be devising a fan solution.

[vestaviascott]

Re: Vizio M43-C1 No Backlights

BTW, it seems later version main boards have a different BGA thermal contact design for the heat sink. Attached is board version 0250 (newer?) compared with 0030 (older?). Hard to tell from top down pic what the new design is. 0030 design is just 2 silver metal alloys impregnated in black anodized aluminum(?) heat sink with rubber heat transfer pad between BGA and heat sink.

Back of the TV in main board area gets really really hot on the plastic rear case where main board is even with short use. I guess Vizio didn't care about longevity here as even the dumbest testing (turn on for 10min haha) would have revealed this. Will be devising a fan solution.

Howard, thanks very much for your documentation of the issue. My TV has the exact same issues as yours.

On the replacement board though, my existing board part number is

VIZIO 756TXFCB0QK003020Q MAIN BOARD for M43-C1

It appears to be the same board as the second image in your post above. Are you saying the two boards attached to your post will work interchangeably? And the newer board has a better heat sink design?

The newer board appears to have a slightly different part number on the UPC sticker:

VIZIO 756TXFCB0QK025020X MAIN BOARD for M43-C1

[howardc64]

Re: Vizio M43-C1 No Backlights

Are you saying the two boards attached to your post will work interchangeably? And the newer board has a better heat sink design?

I don't know that they are interchangeable. Just noting the heat sink design change which probably suggest VISIO finally attempted to remedy the problem. My replacement board was also a 0030 (same as my original that failed) from ebay with minimal hours so I just went with that. Never did devise a fan solution so we'll see how long the 2nd one last.

I tried to reflow the original failed 0030 board with a heat gun + thermal sensor without success. But the big heat sink probably just soaked up the heat applied. Tried to remove the heat sink but need a really good desoldering solution. Friend just got a Hakko desoldering station so will give that a try to remove the heat sink and reflow the 2 hot BGA chips.

[k5la]

Re: Vizio M43-C1 No Backlights

Any progress with adding the cooling fan? I just found an M43-C1 that had been thrown out by the neighbors. After a thorough cleaning, I tried plugging it in and I get no picture or sound, nothing from flashlight test, etc. The power LED flashes 12 times about every 90 seconds or so, but aside from that no signs of life. After reading about so many instances of this same problem, I took it apart to see what my board model number is, and I have an XFCB0QK003020Q board. I ordered a new one online so hopefully that will gain me a new 4K TV, but I'd rather not have to keep getting replacement boards as heat slowly kills them. I am familiar with this issue as I have a 2016 13" MacBook Pro with heat-related screen artifacts that apparently plague this model due to inadequate cooling design and a non-replaceable T-CON board that sits right up against the overloaded CPU heatsink. I want to avoid that type of thing with the TV if possible.

[howardc64]

Re: Vizio M43-C1 No Backlights

Any progress with adding the cooling fan?

Never did put the fan in. Just not much space. Also got a dead Vizio D50u-D1 which had a newer version (newer heat sink design) of the same main board.

Newer heat sink was easier to take off so did that, heat gun reflowed and has worked ever since for a few months now.

*3020Q board has the older heat sink design has really thick soldered on mount points. Can be removed but need good tools. I was able to remove it with 2 people using Hakko desoldering gun and another soldering iron. Unfortunately over cooked the 2 main chips during reflow and killed it for good.

[k5la]

Re: Vizio M43-C1 No Backlights

Never did put the fan in. Just not much space. Also got a dead Vizio D50u-D1 which had a newer version (newer heat sink design) of the same main board.

Newer heat sink was easier to take off so did that, heat gun reflowed and has worked ever since for a few months now.

*3020Q board has the older heat sink design has really thick soldered on mount points. Can be removed but need good tools. I was able to remove it with 2 people using Hakko desoldering gun and another soldering iron. Unfortunately over cooked the 2 main chips during reflow and killed it for good.

I assume you're referring to the XFCB0QK025020X version. Do you know if those work in M43-C1s that had the 3020Q version originally? If so, do you think I should get one of those instead for better longevity?

[howardc64]

Re: Vizio M43-C1 No Backlights

Yes, my D50u-D1 looked like the 5020X version heat sink wise but I didn't record the board model #.

Unfortunately I don't know if 5020X and 3020Q are interchangeable. Sorry.

[wmtodd_h]

Re: Vizio M43-C1 No Backlights

Well, as of yesterday afternoon, our Vizio M43-C1 is experiencing the same failure as neilc6.

• No backlight, no LCD image using the flash light test, and no sound.
• Press power switch, I see the red Optical LED. Front lower left TV power indicator turns on white and fades away shortly after.

I'm trying to source a replacement main board and I see various M43-C1's on eBay, but they do not match my part number (X)XFCB0QK004040X. Any thoughts?

[neilc6]

Re: Vizio M43-C1 No Backlights

High demand and low supply since looks it like all these boards are destined to fail even if you can find a new unused one. Does look like Nicks TVs offers reballing service for this board now.

I picked up a M65-C1 and it's going to cost the same for a new board or to get the existing one reballed. Reballing will probably last longer than a new board. Same symptoms. 12V is 19V present and stable. There is a youtube video for this model for a power supply fix if the 19V isn't stable. PS_On goes high at 3.2V but ON/OFF doesn't.

[howardc64]

Re: Vizio M43-C1 No Backlights

My heat gun reflowed D50u-D1 main board BGAs lasted about a couple of months of medium use (1-2 hour/day) Then the BGA closest to the top of the TV failed again and heat gun brought it alive again.

Going to try mounting a 40mm x 40mm x 10mm 12V 2-pin $1 brushless fan from China on the heat exhaust vents on the back. Plan to use the 18V supply and adding resistor to get to ~6.7V 55mA which yields inaudible fan noise. We'll see assisted flow vs convection might aid in getting rid of heat.

[nomoresonys]

Re: Vizio M43-C1 No Backlights

If that don't work maybe try one fan by the bottom sucking IN fresh air and one near the top pushing OUT hot air.

[howardc64]

Re: Vizio M43-C1 No Backlights

Just an update, looks like these little 2pin $1+ 12v brushless fans runs pretty silent at 5v and 40-50mA draw. Should be easy install by just tapping the 5v supply line and ground lines from PSU that plugs into the main board. Mount the fan on the exhaust ports on the back directly above mainboard. Don't know the flow CFM but if want more air flow, either drop 19v line down to >5V or put in 2 fans. Will be installing soon and modding both of my freebie vizios with this style main board.

[budm]

Re: Vizio M43-C1 No Backlights

I wonder if that 12V fan will always startup at 5V, you may want to find out what the minimum required Voltage for the fan is to start..

[howardc64]

Re: Vizio M43-C1 No Backlights

I wonder if that 12V fan will always startup at 5V, you may want to find out what the minimum required Voltage for the fan is to start..

Good call! Just did a test with my variable power supply. Kick starts at just below 3V so should be good to go right?

[budm]

Re: Vizio M43-C1 No Backlights

Good call! Just did a test with my variable power supply. Kick starts at just below 3V so should be good to go right?

Most 12V will have a hard time starting at less than half the operating Voltage, that is why I have you test it, the spec of the fan will also indicate what the minimum Voltage will be.

[howardc64]

Re: Vizio M43-C1 No Backlights

Got fan install done today. Here are notes for others.

- fan is a cheap $1-$2 12v fan from ebay shipped from China with 40mm x 40mm x 10mm size. Hooked directly to 5v source without resistor yielded very quiet operation. Think could have gone higher voltage and not hear it with TV volume on.

- Both 5V lines (yellow wire) from PSU to main board are not switched so I tapped the USB. Attached pic shows the +- connection on the underside of the main board where USB is. USB has 4 connections with +- on the outer pair with signal on the inner pair. Yellow for 5V and black for ground. If you look closer with a magnifier you can see the - pin has 3 connection points to the ground plane. I put a little shrink tubing all the way up against the solder point for insulation (cover it all with glue gun if you like). Routed the wire upwards where the fan would be and tack down a couple of points on the back of the board with glue gun to avoid tugging on the solder point.

- I just used a couple of zip ties to mount the fan on the exhaust hole ports on my D50u-D1, I'd guess similar on a M43-C1, will do that next. Make sure you point the air flow outwards of course

Use about 12 inches of wires with a connector so can comfortable remove/install TV's plastic backing. 5v is actually available at the wifi connector on top but I didn't know if fan would introduce any kind of noise so decided to just tap the USB. There are a row of holes next to the wifi connector that has switched 12v for anyone wanting higher voltage for higher flow.

If I do this again, I'd tap the 12v switch power near the wifi connector and put a small pot on it so can adjust the speed. 5v is dead silent with speaker off so can get more air flow easily in normal noisy TV operation.

[chillwill96]

Re: Vizio M43-C1 No Backlights

Hello all, just joined the forum and found this post very helpful! I was able to successfully "reflow" my main board's 2 brains with a heat gun without removing the stubborn soldered on heat shield/sink. I just pointed the heat gun straight down at the chip locations about an inch off the surface of the huge black heat sink, and held it there at full blast (an advertised 600F) for 45 seconds each.

At first I was disappointed because the TV didn't turn on right away, but the next morning it turned on and was all good! I'm guessing the reconnection needed a boot time or something (I've read 5 minutes on an electronics supplier website for Vizio's).

Now comes the fan install, does anyone have a photo of what their fan install looks like? Just want to get a feel for what worked and what didn't.

Thanks!