Re: Vizio M470NV will not turn on
the 12v and 5v fuse both are working and the proper voltage coming out. So I would like to restate my question from a few weeks ago.
- We were going down the path that a bad led was causing the unit to shut off after the screen flashed on for a few seconds.
- If this were the (only) issue wouldn't the screen flash on briefly just by pushing the power button the same way it does when the power is "jumpered" on?
- Conversely, if the issue were (only) the mainboard not sending the proper signals to...
bjhunnicutt
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Last Activity: 07-11-2016, 07:16 AM
Joined: 03-22-2016
Location: Ga
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Re: Vizio M470NV will not turn on
I didn't fully ask my question....
- We were going down the path that a bad led was causing the unit to shut off after the screen flashed on for a few seconds.
- If this were the (only) issue wouldn't the screen flash on briefly just by pushing the power button the same way it does when the power is "jumpered" on?
- Conversely, if the issue were (only) the mainboard not sending the proper signals to the power board, would the backlight not stay on when "jumpered" on?
Does,...Leave a comment:
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Re: Vizio M470NV will not turn on
One last question before I start trying to get at the LED strings.
If I can get the screen to flash on initially by jumpering PWR_on and BL_on, why wont the screen flash (with everything connected) when the power on button is pushed (manual or remote)?Leave a comment:
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Re: Vizio M470NV will not turn on
I will post pictures when I get to that stage. It will be a few days though.Leave a comment:
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Re: Vizio M470NV will not turn on
Hmmmm, that could make things interesting then.Leave a comment:
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Re: Vizio M470NV will not turn on
Ok, so it doesn't really change the diagnosis and I will still need to take a look at the LED strings.
Also, I found this picture and description -
[url]http://www.vizpartsdirect.com/productDetail.php?itemInfoId=1763[/url]Re: Vizio M470NV will not turn on<br...oId=1763[/url]Leave a comment:
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Re: Vizio M470NV will not turn on
I don't believe I mentioned it earlier, my mistake.
Can you explain how the protection mode works?
How does that change the diagnosis?
And should I go by a digital one?Leave a comment:
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Re: Vizio M470NV will not turn on
I found these. It is unclear if the associate picture is a generic LED or the specific one
[url]http://vizpartsdirect.com/productDetail.php?itemInfoId=1763[/url]Re: Vizio M470NV will not turn on<br...oId=1763[/url]Leave a comment:
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Re: Vizio M470NV will not turn on
Yes the screen flashes white (a uniform flash covering the entire screen) for about 3 sec then goes black. This did correspond to the VLED to 1-1...4-3 probe test where the voltage goes from 105ish to 0 after about 3 secs. FYI, I am using an analog multimeter.
Also I won't be tinkering with it this weekend, so you will have time to think about it further.
I appreciate everybody's time and input.Leave a comment:
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Re: Vizio M470NV will not turn on
When I get the panel disassembled will that bad string be visually obvious (not lighting up or blackened looking etc) or will I need to do some more testing?Leave a comment:
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Re: Vizio M470NV will not turn on
Because the thread has become a bit lengthy (I appreciate all of the assistance) I thought I would recap where I am with this TV.
While watching tv there was an audible pop and the unit died and wouldn't turn on. After a bit of trial and error I have the following voltages coming off the power supply board.
With PWR_ON and BL_ON jumpered:
5V out of all the 5V
11-12V out of all the 12V
340-360V out of the 450V caps
105-115V out of the VLEDs when tested with the hot probe on the VLED and the gnd on...Leave a comment:
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Re: Vizio M470NV will not turn on
With black probe on the chassis and red probe on 1-1 etc. I get 0v on all 12, not even the temporary 105v I get when doing 1-1 etc to VLED as earlier posted. The screen still flashes for a 2 or 3 count when power is first applied. It looks to be the entire screen, no obvious gaps.Leave a comment:
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Re: Vizio M470NV will not turn on
I didn't notice a big difference between the VLED rails.
Any speculation on what causes the shutoff after a few seconds?Leave a comment:
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Re: Vizio M470NV will not turn on
PS- Thanks for the detailed instructions, I am learning quite a bitLeave a comment:
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Re: Vizio M470NV will not turn on
They will each show 105-110 volts for about 3-5 seconds after the power is turned on then go to zero. This corresponds to the screen flashing on for a few seconds when the power is turned on and then going dim.Leave a comment:
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Re: Vizio M470NV will not turn on
Sorry, CapLeaker but could you elaborate.Leave a comment:
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Re: Vizio M470NV will not turn on
When I turn the power on with the PWR_ON and BL_ON jumpered the screen does flicker initially and then returns to black (or at least imperceptibly dim) I missed it before because I wasn't looking straight at the screen at power up due to the set up of my work space. What does this change?
Also, how do I measure the individual LED strings? Currently I get 110 on all the vleds (far left and far right of each plug) and 0 on the 12 (1-1....4-3) cathode returnsLeave a comment:
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Re: Vizio M470NV will not turn on
So probe each of the 1-1, 1-2 etc pins individually?Leave a comment:
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Re: Vizio M470NV will not turn on
I agree it doesn't make sense which makes me think I am doing something wrong.
I checked the voltage with the hot probe on the vled pin (all four, one at a time) and the ground probe on a point on the frame.
I have done this in a dark room, no light at all from the unit.
Is there a fuse or something downstream of the vleds and prior to the led strings?Leave a comment:
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Re: Vizio M470NV will not turn on
Correct, no backlight with the voltages stated. Also, no sound if it mattersLeave a comment:
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