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Old 01-26-2017, 11:36 AM   #1
DoorOfTime
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Question Vizio E371vl--Decline to failure (diagnosis?)

I've scoured this forum and several others for other E-series Vizio TV's and it seems I've got something unique going on here. I think the way this TV killed itself might grant insight into what went wrong, but I'm hoping some of the folks here might be able to confirm my diagnosis!

I picked up this TV a few days ago off the curb (a promising start, I know!) When I plugged it in everything looked fine--I had full access to the settings menu, IR panel is functional, and all of the buttons worked fine. "Why would somebdoy throw out a perfectly good flat-screen?"

I connected a computer via HDMI. The only thing notable at the beginning was that the speakers weren't working, though that may have been a configuration problem on the computer.

When I played a video at full screen the screen started cutting to black at 'random' intervals. This problem got worse the longer it was plugged in.

Things got weird when I switched to VGA.
  • If a solid black image was placed in the top left corner of the screen (about a 1"X1" square in-set about 1" from the edges), the entire screen was perfectly fine
  • If the same image was completely white, the entire screen went completely dark

I switched back to both HDMI ports and the same behavior happened there--random screen cutting to black for a fraction of a second before coming back up.

I left the TV plugged in but turned off for ~1hr, then turned it back on. At this point the HDMI was crashing completely and the computer was losing the TV as an input. When I tried to turn the TV off, the stand-by power cut out altogether. I left the unit unplugged until this morning.

This morning the screen is exhibiting a "2-seconds to black" behavior. After a hard power reset the stand-by power came back on. When I hit the power button the amber turns white and the "V" logo pops up for ~2 seconds, then the screen goes black and the unit cuts back to amber.

I visually checked all the caps and tested all of the fuses and resistors, nothing looks fried. Stand-by voltage looks fine, I didn't get to test full voltage (I'll need another pair of hands for the 2-second window to test that).

Like I said, let me know what you think! I won't color anybody with my own theories yet, but I'll be sure to follow up if I come up with a solution!
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Old 01-26-2017, 02:03 PM   #2
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Post a high resolution, straight shot picture of your main board. That set has like a half a dozen different main boards.
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Old 01-26-2017, 04:05 PM   #3
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Pictures attached
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File Type: jpg DSCN5825.jpg (846.2 KB, 17 views)
File Type: jpg DSCN5824.jpg (1.17 MB, 26 views)

Last edited by DoorOfTime; 01-26-2017 at 04:21 PM..
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Old 01-26-2017, 05:10 PM   #4
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Update: Plugged the TV in this evening (~10 hours later) and the unit powered up normally. Factory reset all settings, TV reset successfully.

Hooked it to a laptop VGA, screen operated completely normally for ~10 minutes. Tried to change inputs and the TV screen dropped back to standby. Turning it back on goes through the startup then drops back to standby again.

I was thinking this issue was related to EEPROM, but the periodic failures indicate it might be a failed/failing cap, a loose solder joint, or something else that changes during operation (maybe as it gets hot?)
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Old 01-26-2017, 05:21 PM   #5
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

try the old hair drier and freezer spray treatment to locate it .. infra red thermometer might help too
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Old 01-26-2017, 05:23 PM   #6
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Check the supply rail voltage(s) before and during fault condition, if you have a scope and isolation transformer check the rails for ripple. Morel likely though this is a main board problem, suggest cooling and or heating the various chips and semi conductors and observing the behaviour of the set. (must type faster)
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Old 01-27-2017, 05:47 AM   #7
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Put some cooling fan on that Mediatek ARM IC and see if that behaves better.
Next time the unit doesn't boot, freeze the EEPROM with a can of air upside down, then turn the TV on.

Last edited by CapLeaker; 01-27-2017 at 05:49 AM..
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Old 01-27-2017, 06:22 AM   #8
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Thanks for the input everyone. I decided to go ahead and re-solder all of the through-hole components on the main board thinking one of those may have cracked when somebody was jamming input cables into the board--no luck.

I checked every solder joint under magnification and re-soldered anything that looked fishy, but as you can imagine I didn't touch most of the small SM components.

At this point the TV will pretty consistently turn on and I can access the menu. I can switch inputs when nothing is plugged in, but when I
1) plug in a VGA while it's on RGB/VGA input or
--->backlight turns off, white "vizio" shuts off and it goes back on standby
2) try to switch to HDMI at all
--->Occasionally gives "no signal" screen. Most of the time input drops back to TV

Most of the time when it shuts off it will not turn back on immediately. The amber light will blink when the power button is pressed, but the white light will not turn on.

The issue with inputs happens no matter how long the TV has been on, so it seems that there's something more than a heating or solder problem going on. Do these symptoms seem like they could be bad EEPROM?
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Old 01-27-2017, 10:19 AM   #9
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

the HDMI signal going funky is the Mediatek chip. Look how the trace is going from the HDMI directly to the Mediatek IC.
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Old 01-27-2017, 02:09 PM   #10
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

By "going funky", do you think this is a job that re-flowing the board would help or that it's a chip problem and the solution is getting a new one?

I was honestly hoping for an EEPROM problem for the learning opportunity! I've had some good discussions around using an Arduino to dump the EEPROM and compare to a previously compiled dump, maybe even modifying some existing Arduino projects to figure out how to re-write it. Can't even trust the E-series to fail predictably!
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Old 01-27-2017, 06:21 PM   #11
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

try cooling it with a fan first, then reflow, after that either new board or new IC.

Not booting may be a EEPROM issue. So maybe it has 2 quirks. So if it doesn't boot, take a can of air upside down and freeze the EEPROM good. Then turn the TV on with the EEPROM frozen. If it comes back, you need either a firmware update or a new EEPROM.
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Old 01-28-2017, 04:08 PM   #12
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

This morning I plugged the TV in and turned it on--worked for ~10 minutes. I put a fan on it, insulated it a bit so it would heat up, pressed lightly on the chip--nothing changed its behavior. HDMI input flashing problem got worse over time, then the TV shut off and wouldn't turn back on. I unplugged and hard power reset it.

8 hours late I plugged it in and turned it on. It makes it as far as the menu, but when an input is plugged in it crashes. Took it outside for a while to chill--it's under freezing here. Brought it inside and plugged it in, no improvement.

Let it warm up a bit (left it plugged in) and turned it on--made it through start-up then blue screened (that's new... didn't know TV's could blue screen)

This doesn't sound like a cold solder joint to me... I wouldn't rule it out completely, but it doesn't quite make sense.


After hard power resetting and allowing it some down time, I turned the TV on and left it on a TV input--("no channels found"). After ~10 minutes, the TV backlight shut off. Pressing the power button makes the amber light shut off briefly, but it won't turn on.

I re-reset it within 30 seconds of going down so the TV was still warm. Turned it on and made it to the menu. Left it on and timed it--10:18 until the backlight shuts off and the TV loses power.

Third time I was going to monitor the 12V rail from the power strip. The catch? Power resetting it didn't fix it, it won't turn on. I'll give it some time... it'll be back!
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Old 01-28-2017, 04:23 PM   #13
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

freeze the eeprom
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Old 02-01-2017, 08:29 AM   #14
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Finally got a chance to freeze the chips. The TV had been unplugged for ~2 days so it was functional when I turned it on.

Worth noting--the computer I used to connect to HDMI detected the TV as an output whether or not the TV was turned on.

While displaying HDMI on the screen I froze the EEPROM--no apparent change. Shortly after I started chilling the main chip the image cut out, the computer lost the HDMI output, and the TV powered down.

So, it looks like this is a main chip problem. I don't have the equipment to reflow at my apartment, and the only thing I can get my hands on is a heat gun which is a bit barbaric.

It seems odd to me that the chip would have errors both when it has been on for an extended period or when it is chilled. What exactly would be causing that problem?
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Old 02-01-2017, 02:49 PM   #15
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

bad soldering or bad internals in chip ..
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Old 02-01-2017, 05:38 PM   #16
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

You only need flux, solder and a soldering iron to do the Mediatek IC. However I have a feeling that it won't help.
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Old 03-19-2017, 02:10 PM   #17
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

So I finally got around to reflowing the mediatek chip this weekend. After being turned off since my last post, I reflowed the VGA side of the chip (which I had solder bridged before).
The TV worked for a good half hour on a VGA input. I tried to switch to an HDMI and the same old behavior cropped up--power cycling, standby ticking off, etc.

I reflowed the remaining sides of the chip and it kept behaving the same way, until... standby power cut out for good. There was a faint but audible crackle (was that there before?) with the TV plugged in, and 125V AC was going over R101 which was unsurprisingly cooked.

I replaced the resistor and unthinkingly plugged it back in for just long enough to see smoke coming off my new resistor as flux burned off.

The only other component that looks like a short is FB603--does anybody know what that component is supposed to be? No marking on it, though it looks like it may be cooked too.

Last edited by DoorOfTime; 03-19-2017 at 02:12 PM..
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Old 03-19-2017, 02:52 PM   #18
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Did you try Unplugging the tv from the wall
Hold the power button down on the tv, keep the power button down on the tv and plug the power cord back into the outlet.
Keep the power button down until the tv turns itself on and then off.
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Old 03-20-2017, 05:18 PM   #19
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Quote:
Originally Posted by DoorOfTime View Post
The only other component that looks like a short is FB603--does anybody know what that component is supposed to be? No marking on it, though it looks like it may be cooked too.
Ferrite bead probably, it should measure 0ohm so it is good.
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Old 03-25-2017, 06:18 PM   #20
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Default Re: Vizio E371vl--Decline to failure (diagnosis?)

Update:
Looks like I lost the 12V rail but not the 5V rail. Still haven't tracked down my faulty component, open to suggestions.
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