Visio VO47L FHDTV30A No Power, Need Schematic

[MrMoneyMaker]

I have a Visio VO47L FHDTV30A that will not power on. If I hit the power button on the side of the TV, not using the remote, the Visio light on the front of the TV does not indicate any power. I am very familiar with using a volt/ohm meter having done in plant electrical and house wiring. I am however, a novice at electronics but have always had an interest in learning the craft. There is power to the TV, and the 250 volt fuse is not blown. As you can see in the attached pictures, there appears to be a blown capacitor. Would that be enough to cause the no power condition.
Can anyone point me to any specific test points on the board with the corresponding voltages that should be present at that location.

Does anyone have a schematic for this TV.

Any information also on where to get a good online course in electronics would also be of interest to me.

Thanks in advance for your help, and your patience for this novice newbie.

[dskall]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

Need voltages from connector that goes from power supply board to main board. Will need pin#- PIN DESCRIPTION -Pin voltage in standby-Pin voltage when pushing power button and picture of connector on power supply board.
Format:
Pin# - Pin Description - Pin Voltage standby - Pin voltage power on
1 - XXXXXXX - XXv - XXXv
2 - XXXXXXX - XXXv - XXXv
3 - XXXXXXX - XXXv - XXXv
4 - etc.
May need pictures of back of power board

[budm]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

Check the resistance between the two legs of that Blue disc snubber cap, set the meter to 200 Ohms scale.

[attainteddragon]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

if you are serious about gaining some more knowledge in electronics,
take a look at www.learnabout-electronics.org
there is a lot of information there that can help you stuck into things.
and read lots of badcaps threads.

[dick_barton]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

You need to check all the components around the blown capacitor for damage. The mosfet, diodes and zeners located in that area. Put you meter into diode mode to test the components.

A clear photo of the underside of the power board would be useful.

[MrMoneyMaker]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

Need voltages from connector that goes from power supply board to main board. Will need pin#- PIN DESCRIPTION -Pin voltage in standby-Pin voltage when pushing power button and picture of connector on power supply board.
Format:
Pin# - Pin Description - Pin Voltage standby - Pin voltage power on
1 - XXXXXXX - XXv - XXXv
2 - XXXXXXX - XXXv - XXXv
3 - XXXXXXX - XXXv - XXXv
4 - etc.
May need pictures of back of power board

Here is an image of the back of the board, and also images of the connector on the power board.
The snubber capacitor measures 69.5 ohms.
I am not familiar with the band on the diodes whether that is the flow through side or the stop/check valve side.


Meter set to Diode.
With positive on the band side, negative on the opposite side I got the following values and then reversed.


Band side to the left(POS) and then reversed Band side to the left (NEG/GND)
Component #

ZD 991

1 POS        GND/GND    POS 580

D991

1 POS        GND/GND    POS 580

D984

636 POS      GND/GND    POS 484

ZD725

389 POS      GND/GND    POS 249

ZD902

109 POS      GND/GND    POS 107

Are the voltages on the connector going to the main board going to be AC or DC. Also, are the voltages at the diodes and snubber capacitor going to be AC or DC? I get readings on both settings. Thanks for the help.

[budm]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

Remove that snubber cap and measure resistance of that cap off the board, then also measure the resistance between the two pads where the cap was solder to to see what you have.

[dskall]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

"Any information also on where to get a good online course in electronics would also be of interest to me".
I started by watching youtube video's first the bulging caps videos then the more professional like norcal715. Learned a lot there. Now learning a lot on badcaps

[attainteddragon]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

i have some links to some other online courses and info, but havn't gone through it all yet.
i'll update things when i work out what is quality info and discard the rest.

i started with youtube and threads here, then wanted to try to grasp more information.
it would be good to find something that goes from gate logic to dc to dc converters and so on.
pfc circuits simplified would be awesome too.

[dskall]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

I have been going through your link above. I like the buck and boost tutorial. My interest is TV oriented understanding and troubleshooting. Hard to find a site that focuses on TV repair

[MrMoneyMaker]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

OK, I pulled the diodes out of circuit and they checked out OK.

The snubber capacitor measured 68.4 ohms

The zener diode ZD725 measured 898 Ohms with pos lead on the cathode side and neg lead on the anode side, and 308 Ohms with the leads reversed.

The zener diode ZD902 measured 1602 Ohms with the pos lead on the cathode side and neg lead on the anode side, and 459 Ohms with the leads reversed.

As you can see in the attached photos, I found some other issues. 2 burnt resistors, a burnt IC, and some other burnt parts.

Would I be better off just replacing the power board? Where is a good place to source a new or good used/refurbished board. If this is repairable, where do I get the parts, and how do I know the value of the fried resister that can't be read because the markings are all burned up?

Thanks again for the input and assistance.

[dskall]

Re: Visio VO47L FHDTV30A No Power, Need Schematic

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