Vizio VF550M 55 in. LCD HDTV Logo
DAN HYLDELUND Posted on Oct 16, 2010

I have a Vizio VF550M lcd tv that has no backlight/picture. There is no visual signs of bad caps or burnt spots on any of the boards. All the fuses are checking good in circuit. I followed budmrtn's lcd troubleshooting guide and voltages from the power supply look good when I turn it on. 5v,12v,24v. However they wont turn off unless I unplug the cord. The guide tells of a bl_on signal from the logic board to the inverter board that I could not find, I think it gets this signal back thru the ps board? I have 2 inverter boards but no connections to either from the logic board directly.The only connections on the inverter boards are from the ps board and to the light tubes. They are joined together via a cable, I guess master and slave. I read the 24v would shut down if there was a bad inverter, and it does'nt. The fact that the voltages wont shut off is leading me to think its the logic/main board but want to see if anyone thinks I should look elsewhere first. Thanks... Dano

  • DAN HYLDELUND Oct 25, 2010

    UPDATE. I changed the main board and it works.

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5 Related Answers

olayoju victor

  • 191 Answers
  • Posted on Nov 10, 2008

SOURCE: VIZIO LCD 26 INCH model# VW26L HDTV10F NOT TURNING ON

unplug ur backlight inverter plug &power on to see ,if it doesnt on , change ur mainboard

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budmrtn

Bud Martin

  • 11361 Answers
  • Posted on Jul 05, 2010

SOURCE: Vizio SV470XVT1A has no backlight

The 24vdc is turn on by the signal from the main logic board, it is not always on, the standby 5vdc is always on. So yes it can be the power supply board is bad, but just to besure we need to find out if it is getting the turn on signal from the main board first.
You can have 24vdc at the inverter board and it will not light up the CCFL until it gets the signal from the main logic board to turn the lamps on (this is the STANDBY condition, the TV is on but the screen in not lit up util it see the video signal).
Send me good clean and clear pictures of the power supply board, [email protected], connectors of the Power supply, bottom side of the board, then I may be able to tell you which pin is a control input pin. Most people will just throwing parts in and hope that they one of the parts will fix the problem. Used Power supply module for this TV is over $100. http://www.google.com/products?rlz=1T4GGIH_enUS282US283&q=delta+DPS-379AP&um=1&ie=UTF-8&ei=USsxTKn3J6TonQfFlJGEBA&sa=X&oi=product_result_group&ct=title&resnum=4&ved=0CCsQrQQwAw

http://www.shopjimmy.com/catalogsearch/result/?q=Vizio+SV470XVT+

Testimonial: "Bud helped me fix my TV! It was only 1 1/2 years old. I was looking at a repair bill close to $300 - $500 and I fixed it with a $60 board! Thanks!!!"

budmrtn

Bud Martin

  • 11361 Answers
  • Posted on Sep 07, 2010

SOURCE: insignia ns-lcd47hd09 i check voltages again solid

It means the feedback circuits for regulating the 12/24vdc is not working, use 12v car bulb (1157) to load down the 12vdc supply and two 1157 is series to load down the 24vdc power supply and see it if still rises up, the stange thing is that you said it rises to 36vdc (12 + 24 = 36), is it being measure correctly?

http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide

Failed TV and Monitors: http://s807.photobucket.com/home/budm/allalbums

http://en.wikipedia.org/wiki/Capacitor_plague

Parts: www.shopjimmy.com
Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.

Testimonial: "great were almost there A+++"

electricdime

Electric Dime

  • 434 Answers
  • Posted on Dec 04, 2010

SOURCE: When plugged in, the

It is probably the capacitors on the power supply. Check them. I think there are 3 in a row. They are red in color and 450W. There is also a larger one next to them but I do not remember the volts.

budmrtn

Bud Martin

  • 11361 Answers
  • Posted on Dec 06, 2010

SOURCE: When plugged in, the logo flashes white.

The 5vdc standby is working but not the 12 or 24v?
You need to find out if the power supply board is getting PS_ON signal from the main board to turn on the 12/24vdc power supply section.
Please read my guide to get some understanding first.
If you are going to DIY and have proper tools, electronics knowledge, and know safety precaution then please read on:

Please see my basic troubleshooting guide here:
http://www.fixya.com/support/r5093881-lcd_flat_panel_tv_troubleshooting_guide
http://www.fixya.com/support/r6150077-basic_lcd_monitors_troubleshooting
Failed TV and Monitors: http://s807.photobucket.com/albums/yy352/budm

Learn about bad caps: http://en.wikipedia.org/wiki/Capacitor_plague

Parts: www.shopjimmy.com
Capacitors kit: http://lcdalternatives.auctivacommerce.com/Default.aspx he can make you a set of caps.
Or www.digikey.com just make sure to use caps with low ESR, 105c rating such as PANASONIC FM or FC series.
Please post back what you find.

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Parts: http://www.shopjimmy.com/catalogsearch/result/?q=VIZIO+VO47L

Basic troubleshooting guide here:
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Failed TV and Monitors pictures: http://s807.photobucket.com/albums/yy352/budm/
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NOT WORKING

do a visual inspection and see any thing is burnt or open.
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