Vizio standby light but will not power on

[kmcbride1981]

I recently was given a Vizio P42HDTV10A from a friend. When i opened the back I checked the power board and the caps were bad. I went to replace the caps and the bottom of the board was burnt were the caps are soldered. I replaced the board with another. The standby light is orange, but nothing happens when the power is pressed. Any suggestion would be appreciated.

[tom66]

Re: Vizio standby light but will not power on

These Vizios seem to have a problem with a certain voltage regulator, U33, failing, causing the symptoms you describe. One symptom is the TV will turn on, the light will turn white, the backlight will light up but then no picture - does your set have this problem?

You'll need to post some clear photos of the boards, in particular the main board.

[kmcbride1981]

Re: Vizio standby light but will not power on

tv will not power on at all, it just stays in the standby mode. pics coming.

[kmcbride1981]

Re: Vizio standby light but will not power on

pics

[tom66]

Re: Vizio standby light but will not power on

My error. I had thought you might have an LCD on your hands, but it's a plasma. I don't think U33 fails on these models but I could be wrong.

Do you have a multimeter?

[kmcbride1981]

Re: Vizio standby light but will not power on

yes

[tom66]

Re: Vizio standby light but will not power on

yes

Great. Post a clear, focused picture of the main board. I'll highlight some checks.

Late here (1:29am GMT), might not get back to you until morning.

[kmcbride1981]

Re: Vizio standby light but will not power on

thanks

[tom66]

Re: Vizio standby light but will not power on

Thanks for those pictures; clear and focused.

I've highlighted some points, they have a letter next to them which I will refer to.

A: Unplug TV and wait until standby light goes out. Use the diode test on your multimeter to check this device. Set the meter to the position which looks like a diode (sort of like this: ->|-). Place the red lead on one terminal and black on the other; report back the reading. Then, reverse the leads, and report back the reading. One way, you should get 150 - 750; the other way you should get no reading (a single lefthand 1 or "OL" is common.)

B: Report back the part number for this device; I can't tell if it's a regulator. Also, looks like Vizio skimped out on bolting this device down properly which makes it vulnerable to movement. E.g. if the owner moved home with the TV it could have dislodged a solder joint. This will be visible upon inspection with a loupe or a magnifying glass but no need to check it for now as it's a less likely fault than others.

C: This is an SMD fuse. Turn on your multimeter and set it to the 200 ohms range. Touch the two probes together and note the reading (it should be in the neighbourhood of 1-2 ohms.) Then, while the set is off, place the red probe on one end and the black probe on the other end (it doesn't matter which way around.) You should measure a few ohms; note this reading down, then subtract your probes together reading, it should be less than 1 ohm.

D: Have the TV switched on in the fault condition (i.e. stuck in standby.) Connect the negative probe of your multimeter to an exposed part of the metal case, such as a screw hole. Touch the probe carefully on each pin and note the readings down. (By the way, this is an LDO / voltage regulator. They sometimes go bad.) Then, record the part number on the device - it will be something like AP1117-33. The last two digits are significant; they indicate the output voltage (in this case, 3.3V.)

E: (second pic) Another LDO, test as above.

F: (second pic) Another LDO, test as above.

[kmcbride1981]

Re: Vizio standby light but will not power on

A = 0.134 0.229
B = F43 KA7809
C = 0.000 (has auto range)
D = 0.000 at all contacts there is not a part #
E = 0.000 at all contacts
F = 0.000 at all contacts

[kmcbride1981]

Re: Vizio standby light but will not power on

There is power going to into the sub power board (121v) and the main power board (121v), however there is none to the power button nor on the main board. So c, d, e, and f should be reading 0V.

[kmcbride1981]

Re: Vizio standby light but will not power on

pic from another p42hdtv10a

what is this cable? I do not have this.

[PlainBill]

Re: Vizio standby light but will not power on

pic from another p42hdtv10a

what is this cable? I do not have this.

Which cable? There are two that are circled. You have a black & white twisted cable going from the power supply to ??? On the other TV it is reddish (pink?) wires in a black sheath going to a connector on the end of the main board.

PlainBill

[selldoor]

Re: Vizio standby light but will not power on

pic from another p42hdtv10a

what is this cable? I do not have this.

Hi From the schematic it looks like this cable goes from CN01 on the power board to J9 on the main board.? Does your board have these sockets marked
as CN01 and J9. - It looks like it is a power cable and perhaps the socket J9 will show voltages on the back of the board?.
You do however have a cable from CN01 (Twisted Black&White ) where does it go to?
Are you sure this is the same set? not another model?

UPDATE: Cableing may be a red herring see "Vizio P42HD and P42hdtv10a interchangeable parts?" it has a pic of P42hdtv10a looks same as yours - no cable.
There is also a current thread on the go regarding the same set/model and I have asked them to post
pics of their cable/sockets. "42 inch Vizio Plasma Pop No Picture"

[kmcbride1981]

Re: Vizio standby light but will not power on

the reddish connector on the end of the main board that goes under the main board chassis.

[PlainBill]

Re: Vizio standby light but will not power on

the reddish connector on the end of the main board that goes under the main board chassis.

That cable appears to go the the logic main board, or maybe to either the control panel or to the remote sensor.

PlainBill

[kmcbride1981]

Re: Vizio standby light but will not power on

I replaced the main board and logic control board. I got them for $65 shipped (ebay). Plasma is up and running. Thanks for all the tips and help.

[tom66]

Re: Vizio standby light but will not power on

Nice!

[tmetz]

Re: Vizio standby light but will not power on

Nice!

[ETCBOB]

Re: Vizio standby light but will not power on

Curious since I am having the same problem. Were both, the main board and logic control boards needed or just one? I am finding these boards difficult to find. I may have to troubleshoot to the component level.