Vizio M3D421SR

[24V]

I have a Vizio M3D421SR no sound, no image, TV powers up and the logo light turns white. Power board board voltage 23.89v, 5.217v, 12.2v main board# 715G4404-M01-000-005K

[mu2]

Re: Vizio M3D421SR

Hi,

I have the same tv, same problem, exactly the same main board. I could not find the problem and sent the main board out to be repaired.
I used the repair service currently offered on E-bay for $89. I highly recommend their service. Very fast turn around and they fixed the problem.
Apparently, this is a common problem with this tv but the solution isn't common knowledge.
I'm still trying to find a set of internal speakers for this tv. Would you be so kind as to post any numbers that are marked on them - or posting a good photo would be appreciated.
I got the set from a recycler and the speakers were missing.
Good luck - if you find the problem please post.

Mike

[24V]

Re: Vizio M3D421SR

Thanks Mike, here is the speaker information. If possible someone please post a diy fix here.

Thanks.

[cashkennedy]

Re: Vizio M3D421SR

Vizio sets usually have problems with the DC-DC voltage regulators on the mainboard. Although your specific model is not one that i have run into with this problem before. But if it is the DC-DC regulators this is a widely known problem with many MANY posts on this site explaining how to fix it. Basically you need the service manual, and in the service manual it indicates the order to test the DC-DC regulators with a multimeter... Usually its a amc1117 LDO regulator. and instead of converting 5v to 3.3v it will be producing less.

[mu2]

Re: Vizio M3D421SR

24V,

Thank you very much for posting the speaker photos. Looks like the speaker is some kind of combination woofer and tweeter. At least I have part numbers that I couldn't get from Vizio.
Regarding the problem on the main board. I suspect that problem is in the area of the processor - perhaps poor solder joints. Just a hunch!

Mike

[hollow256]

Re: Vizio M3D421SR

Has anyone fixed this issue? I have a unit with the exact same problem and have searched high and low for a solution. I Have tested ps voltages and the voltages on the regulators. one regulator was low and i replaced it to no avail. there is still another regulator which is a little low. it reads 3.28 out it is supposed to be 3.3 is that too low?

Anyone have any technical documentation for this or related models?
m3d420sr, m3d460sr, m3d550sr

the motherboards are almost identical physiclly with the 420 and 421 being the same.

I really dont want to send the board to the ebay guy as i have already replaced a regulator and he may not want to work on it.

[tom66]

Re: Vizio M3D421SR

3.28V is fine for a 3.3V regulator. General rule is ±2%.

[nuala]

Re: Vizio M3D421SR

This sounds like an eeprom problem. I would check with Shopjimmy.com and see if the eeprom is available for this model.

[rcangler3]

Re: Vizio M3D421SR

Was there any success to your problem? I am having the same issue and would like to repair the item myself. Please help!!

[hollow256]

Re: Vizio M3D421SR

No I have not solved this issue yet. I decided to use the $89 repair service on ebay and am waiting for them to finish. Ill let u know how it goes

[rcangler3]

Re: Vizio M3D421SR

I am about to do that myself. I've looked everywhere I could to find the problem so I could fix it myself and I could not find any answers. The ebay repair service may be my last hope otherwise I am stuck with with a useless item.

[hollow256]

Re: Vizio M3D421SR

i got my main board back today and the tv is working fine. after talking to the repair guy from the ebay service and thoroughly inspecting the board im pretty sure they just reflowed the solder on the processor much like you would do to a xbox360 with rlod or ps3 with ylod. they also changed a voltage regulator but the one they changed i had already changed. it was the 1117-18 regulator which i had swapped with one from a 360. i have encountered other main boards with the solder issues as well. infact it seems like this is an issue amongst all surface mount processors as they produce heat and the boards in tvs are very likely to flex and pop the solder joints. good luck with your repair. i highly recommend the service for anyone who is not able to reflow the chip themselves. in the future i will be doing this myself. oh and a side note: i am a technician at a tv repair shop, i got this tv for free because we could not find a replacement main and the cx asked us to dispose of it. $89 for a smart tv oh yeah!!!

[rcangler3]

Re: Vizio M3D421SR

Thanks hollow for posting from your experience! I went to go buy this ebay service and send to the guy but he took the listing down a week ago and didn't know what to do. I have a technician background but am still an amateur so I guess i will try what you said and see if i can get this thing workings so it wont just be junk in the way

[rcangler3]

Re: Vizio M3D421SR

What about resetting the eeprom? is that a possibility?

[hollow256]

Re: Vizio M3D421SR

Try searching for m3d420sr mainboard repair I know I couldnt find it under 421 for some reason.

[NickLoC]

Re: Vizio M3D421SR

Anyone ever figure out how to repair this without sending it out for $89? If it's a reflow issue, can you do the heatgun trick?

[NickLoC]

Re: Vizio M3D421SR

Anyone have any advice on this? The tv I have, when plugged in, the vizio logo lights up white. Power button does nothing. Power voltages are the same as other people have posted on here. Would like to not send out the board. Wondering if a heat gun reflow would work. Like the xbox360.

[ny_jets_head]

Re: Vizio M3D421SR

Did they provide any detail as to what they did to repair the board?
Thanks!

As for re flowing Large chips with a heat gun... not a permanent fix.
The issue is the solder melts they use melts at a lower temp caused by the chip generating too much heat. The chip has to be re balled with higher temp solder and possibly a better heat sink installed to dissipate the heat.
A good fix is to replace the chip as it is getting exposed to excessive heat from use and during the repair.

[harleycowboy61]

Re: Vizio M3D421SR

on the vizio m3d421sr, the problems can start with the power U709-mosfet ic chip or u703-gate and D701-diod, if the voltage is correct for these then it is the command video chip, it has to be reworked and replaced from over heating. these TV's are not made for playing video games on, x-box will kill this video from over heating, the heatsink is too small for the load