Vizio M43-C1 No Backlights

[howardc64]

Re: Vizio M43-C1 No Backlights

375F is 190C, lead free solder melts at 423F or 217C, it's not surprising your oven reflow isn't lasting.

Good point based on science! Don't know how long oven reflow method will last yet. Chose 375F-400F based on most internet postings on oven reflow for TV and laptop main boards. Wondering if something like 425F for 5min in an oven is safe on these boards?

Of course oven temp control isn't great and we don't really know what temps are at the BGA balls. Best would be a professional BGA rework station with precise temp, thermal profile, and much shorter duration of course but not really available to us consumers and not worth paying a pro to fix these cheap TVs. Really only fixing these to keep it out of landfills. These Vizio TV main boards are lasting between 2-5 years max.

[johnboiles]

Re: Vizio M43-C1 No Backlights

@howardc64: how long ago did you oven reflow those last two TVs? How long have they been operating for after the relow?

I was looking around for a replacement board and it seems they're out of stock most places. There are some on eBay that are used and >$100. Any surprising sources for parts other than Googling + eBay?

My M50-C1 has a LTCWSPBR* serial number. The main board has the nubmers `GXFCB0QK012020X` and `715G7288-M01-000-005K`. Though from looking around online it looks like the part number `756TXFCB0QK0120` should also work on my tv.

[diif]

Re: Vizio M43-C1 No Backlights

375F is 190C, lead free solder melts at 423F or 217C, it's not surprising your oven reflow isn't lasting.

[howardc64]

Re: Vizio M43-C1 No Backlights

@howardc64 did you really do 375C or did you mean 375F?

Yikes, I meant 375F, wish I can correct the original post to not misinform someone. I'll message the admins.

And great you fixed the board. Mine smoked minimally but maybe because I removed the heat sink and cleaned up the thermal paste underneath.

As for oven, big convection oven is probably best for even temps. Didn't want to mess up wife's Viking. Convection toaster is probably next best and my cheapo freebie toaster oven the last resort. I did check the temps with laser thermometer (measured top and back wall) before use and was comfortable temp dial setting was close.

Most people put the board up on stand offs (eg aluminum foil balls) on a metal sheet (or cardboard with aluminum foil on top, punch some holes to vent so foil don't inflate upwards toward the board). Leave the board alone after reflow (oven door open) so it can cool. Don't take it out while hot, I've heard of components falling off.

BTW, my heatsink has a really thin plastic sheet (see attached) on top that lifted off when I removed that tape/aluminum foil on top. Not sure why the sheet is there, can't be good for thermal transfer? But I've given up trying to understand Vizio's design on this main board. The entire cooling solution is typical of modern TV main boards but perhaps the BGAs are on older semiconductor technology that put out too much heat for this thermal solution.

The 3 Vizio TV I have all had his common problem with same basic board design.

2015 M43-C1 (removed heatsink, popcorned the main board with heatgun, replaced with new board from ebay)
2015 P502UI-B1E (no vizio logo, backlight on, no video. oven reflow and worked)
2016 D50U-D1 (dead with blinking lights. Removed heat sink, heat gun reflow, worked few weeks of light use, 1/2 screen noise, oven reflow and worked)

[johnboiles]

Re: Vizio M43-C1 No Backlights

Also, y'all's main boards this crusty on the back? I assume it's just dried flux, but seems like more than I would expect there to be. The crusty bits liquified into a kinda oily substance after toasting it. If I have to do this again, I'll probably go at it with some alcohol because why not.

[johnboiles]

Re: Vizio M43-C1 No Backlights

I have much better luck recently with 10min bake at 375C in a toaster oven.

I just had success toaster-oven-ing my M50-C1's main board! Your post gave me the courage. I did 375F for ~8 minutes with the heatsink left on but the thermal rubber things on the back scraped off. @howardc64 did you really do 375C or did you mean 375F? I chickened out short of going the full 10 minutes when the board started putting out a good bit of smoke (probably just smoke from the old flux). But it's been working so far today. I'm not holding my breath for longevity but I'll report back when/if it fails again.

As a data point, my issue first started with the right half of the screen becoming garbled (which seemed like a tcon issue). Then a day or two later the TV stopped coming on at all (no backlight). The white LED would blink 10 times a bit after coming on. Later it started blinking 15 times after coming on. I also had 19V on the 12V power supply line.

[howardc64]

Re: Vizio M43-C1 No Backlights

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.

[GeorgeT]

Re: Vizio M43-C1 No Backlights

I ordered the TM902C Temperature Meter and some fake Amtech flux from Banggood. I'll continue the testing when my package arrives. Thanks for all of your help.

TM902C Temperature Meter...
https://www.banggood.com/TM902C-LCD-...r_warehouse=CN

Fake Amtech flux...
https://www.banggood.com/2pcs-AMTECH...r_warehouse=CN

[nomoresonys]

Re: Vizio M43-C1 No Backlights

I don't mess with it too often, last time I just grabbed a little bottle off ebay, used the no-clean, it was: http://stores.ebay.com/Dickies-Garage-Sale

[GeorgeT]

Re: Vizio M43-C1 No Backlights

Thank you nomoresonys & diff for your great advice. I will definitely order one of those TM902c meters today. Without it, I am working in the blind. Also I will try to match that heat profile as close as possible. What would be a good, no clean flux to use that you have had good experience with?

[diif]

Re: Vizio M43-C1 No Backlights

Thanks for your reply Neilc6. I will stay focused on reflowing the processor on the main board then. What is a safe amount of time to keep the heat gun pointing at the processor? My heat gun is a Master heat gun hg-501a that goes from 500 Degrees to 750 Degrees F. It moves a lot of air at 23 cfm.

Get yourself one of these and stick the thermocouple near the processor. https://www.ebay.com/itm/TM902C-LCD-...L/262799900021

And try to follow this profile. https://en.wikipedia.org/wiki/Reflow...a_Profile1.svg

To reduce the chance of thermal shock and damage, pre heat the whole board in the oven to 100c for a few minutes before removing, adding flux and using your heat gun. Done right and a reflow will last a decent amount of time.

[nomoresonys]

Re: Vizio M43-C1 No Backlights

Check youtube for those reflow procedures, not all of them know what they are doing but you will know when you hit a good one, they will describe it in every detail from the temp to use to how long, some gradually move the heat closer hit it for a while then gradually back off, it is pretty easy to cook them if they are overheated, under-heating won't hurt them, you just won't get any results.

[GeorgeT]

Re: Vizio M43-C1 No Backlights

I just unplugged the wifi module, but no luck. Thanks for the suggestion.

[nomoresonys]

Re: Vizio M43-C1 No Backlights

Could try unplugging the cable at the wifi module and see if tv comes on, sometimes when that has a problem the tv won't work right, just something easy to try.

[nomoresonys]

Re: Vizio M43-C1 No Backlights

Wonder if it's the eeprom, shopjimmy has some and there's several on ebay: https://www.ebay.com/sch/i.html?_fro...acat=0&_sop=15

Be advised that there are at least a couple different mainboards for this model tv.

[GeorgeT]

Re: Vizio M43-C1 No Backlights

Thanks for your reply Neilc6. I will stay focused on reflowing the processor on the main board then. What is a safe amount of time to keep the heat gun pointing at the processor? My heat gun is a Master heat gun hg-501a that goes from 500 Degrees to 750 Degrees F. It moves a lot of air at 23 cfm.

[neilc6]

Re: Vizio M43-C1 No Backlights

ON/OFF (BL-ON) signal not going high. Should be at same level as PS-ON. Signal comes directly from the processor.

[GeorgeT]

Re: Vizio M43-C1 No Backlights

I removed the back cover on the Vizio D55u-D1 and used a heat gun to heat up the heat sink. I keep it on for 45 seconds, moving it all around to heat it evenly. After 15 seconds, I plugged the TV in and turned it on. Still no picture. I tried this several times. I then removed the large heat sink and used the heat gun to heat up both BGA chips for around 6 seconds on each one. I let the board cool for a few minutes, then plugged it in. Still black screen. Maybe I'm not keeping the heat gun on the chip long enough. It's about 1/2 inch away from the chip and the gun is around 500F.

My voltages are just like Macair1's from an earlier post...
CN9101: DC voltages when TV is plugged in and is ON:
Pin1 ON/OFF = 0.10
Pin 2 DIM = 3.32
Pin 3 3D_ON = 0.00
Pin 4 PS_ON = 3.70
Pin 5 GND = 0.00
Pin 6 GND = 0.00
Pin 7 GND = 0.00
Pin 8 GND = 0.00
Pin 9 +12VA = 19.10
Pin 10 +12VA = 19.10
Pin 11 +12V = 19.10
Pin 12 +12V = 19.10
Pin 13 +12V = 19.10
Pin 14 +12V = 19.10
Pin 15 +5V = 5.17
Pin 16 +5V = 5.17

Is is usually the main board?

[nomoresonys]

Re: Vizio M43-C1 No Backlights

Fans help out in most situations: https://cdn.badcaps-static.com/pdfs/...9d3b50b881.pdf

[GeorgeT]

Re: Vizio M43-C1 No Backlights

Hi Nick. Specifically what flux would you use for a BGA reflow? I have a Vizio D55u-D1 that does not power up. I will use my Master heat gun that has a temperature range of 500F to 750F to warm up the heat sink (as you mentioned in other threads) to see if the problem is with the BGA's. If the TV powers up, then I will want to remove the heat sink and try to reflow the chips properly. Thanks for any help.