Badcaps.net Forum
Go Back   Badcaps Forums > Troubleshooting Hardware & Devices and Electronics Theory > Troubleshooting TVs and Video Sources
Register FAQ Calendar Search Today's Posts Mark Forums Read

 
Thread Tools Display Modes
Old 11-10-2012, 07:34 PM   #1
marlboroa
Member
 
Join Date: Jul 2012
City & State: wichita falls TX
My Country: USA
I'm a: Knowledge Seeker
Posts: 52
Default VIZIO VX37L No picture or sound.

I have a Vizio VX37L that does not have a picture or sound. the Light in front will turn from orange to white when you push power but the tv does nothing. I will also not turn back off, you have to unplug it.
All the voltages on the power supply seem correct so checked the regulators on the main board. they are as follows. Do they seem correct or do i need to change some out?

AMC117
f0722f

U7 3.21
1.11
0.02

U33 5.09
3.22
1.98

U8 5.11
3.25
2.01

U2 5.09
3.26
2.02

U4 5.09
3.28
2.04

K117515
730

U9 3.21
1.49
0.00
marlboroa is offline   Reply With Quote
Old 11-10-2012, 09:02 PM   #2
marlboroa
Member
 
Join Date: Jul 2012
City & State: wichita falls TX
My Country: USA
I'm a: Knowledge Seeker
Posts: 52
Default Re: VIZIO VX37L No picture or sound.

I did test the power supply and i have all the voltages except for A and B they read 0
marlboroa is offline   Reply With Quote
Old 11-10-2012, 09:46 PM   #3
budm
Badcaps Veteran
 
budm's Avatar
 
Join Date: Feb 2010
City & State: S.F. Bay area
My Country: USA
Line Voltage: 120V 60Hz
I'm a: Knowledge Seeker
Posts: 39,206
Default Re: VIZIO VX37L No picture or sound.

If you are reading 0V at A and B, A and B are the control signals generated by the main board to turn on the backlights and Dimming control. Are you getting PS_ON >3VDC?
Can we see good clear pictures of the boards? Is this the same as your TV?
http://s807.photobucket.com/albums/y...37L%20HDTV10A/
You voltage reading of the regulators are a little confuse.
If you look at the regulator 1117 series with the big tab up
Fixed output regulator:
Left pin (1) will be Ground
Center pin or Tab (2) will be output pin
Right pin (3) will be the input pin

Adjustable output regulator (it will need two resistors, one is between Ground and Adj pin, another one is between Adj pin and Output pin):
Left pin (1) will be the Adust pin.
Center pin or Tab (2) will be output pin
Right pin (3) will be the input pin

This is the way to figure out if the adjustable regulator is good or not:
Notes: we are looking at the regulator with the Big tab up (the big tab is tied internally to the center pin).
Adjustable regulator will have two resistors attached to it, one resistor (Rfb) is between pin1 and pin2, another resistor (Rg) is between pin1 and ground. Pin3 is an input pin.
The voltage between the Adjust pin (left pin) and the center pin (Pin2, output) will always be 1.25V +/- 2% (this is the precision voltage reference), if it is not, it is bad.
To figure out what the output voltage should be: measure the voltage between pin 1 and ground and add 1.25V to that number, that is the output voltage on pin 2 but you have to make sure you do have 1.25 between pin 1 and 2 as noted above.
So can you label the pins and the voltage you are reading on those regulators?
AMC117
f0722f

U7 P/N?
3.21
1.11 This one does not look right
0.02

U33 P/N?
5.09
3.22 This one should be 3.3
1.98

U8 P/N
5.11
3.25 looks OK (1.25 +2.01 = 3.26)
2.01

U2 P/N?
5.09
3.26 looks OK (1.25 + 2.02 = 3.27)
2.02

U4 P/N?
5.09
3.28 looks OK (1.25 + 2.04 = 3.29)
2.04

K117515
730

U9
3.21
1.49 looks OK, it looks like 1.5V regulator.
0.00
__________________
Never stop learning
Basic LCD TV and Monitor troubleshooting guides.
http://www.badcaps.net/forum/showthr...956#post305956

Voltage Regulator (LDO) testing:
http://www.badcaps.net/forum/showthr...999#post300999

Inverter testing using old CFL:
http://www.badcaps.net/forum/showthr...er+testing+cfl

Tear down pictures : Hit the ">" Show Albums and stories" on the left side
http://s807.photobucket.com/user/budm/library/

TV Factory reset codes listing:
http://www.badcaps.net/forum/showthread.php?t=24809
budm is offline   Reply With Quote
Old 11-11-2012, 10:46 AM   #4
marlboroa
Member
 
Join Date: Jul 2012
City & State: wichita falls TX
My Country: USA
I'm a: Knowledge Seeker
Posts: 52
Default Re: VIZIO VX37L No picture or sound.

The picture of the main board in your link is just like mine. same part number and all. I took the readings clockwise. so since the big tab is to the left i guess the way i listed them would be
3
2
1
I do have a PS_On reading of 3.07 which seems a tad low.
The part numbers for the U regulators are all AMC117 f0722f except for U9. its a
K117515 730
marlboroa is offline   Reply With Quote
Old 11-12-2012, 09:03 AM   #5
marlboroa
Member
 
Join Date: Jul 2012
City & State: wichita falls TX
My Country: USA
I'm a: Knowledge Seeker
Posts: 52
Default Re: VIZIO VX37L No picture or sound.

how can i get the U33 up to 3.3 volts?
marlboroa is offline   Reply With Quote
Old 11-12-2012, 09:05 AM   #6
tom66
EVs Rule
 
tom66's Avatar
 
Join Date: Apr 2011
City & State: Leeds
My Country: UK
Line Voltage: 230Vac 50Hz
I'm a: Professional Tech
Posts: 32,373
Default Re: VIZIO VX37L No picture or sound.

You should re-test U33. If it still shows low 3.22V, it could be faulty and should be replaced. However, U7 looks worse, as budm pointed out.
__________________
Please do not PM me with questions! Questions via PM will not be answered. Post on the forums instead!
Free service manuals: http://www.toms-service-manuals.com/ -- 72 LED/LCD TVs, 5 monitors, 28 plasma TVs, and 2 AVR 6.1 amplifiers fixed! -- I repair Pioneer 9G Plasma Main Boards & KRP-M01 Media Receivers (PM me for info)

2 Pioneer KURO 9G, 12 Panasonic LCD/Plasma, 1 Sony LCD, 1 NEC Plasma, 2 Yamaha HTS, 5 Sharp LCDs, 5 Toshiba LCDs, 7 Philips Plasma/LCD, 1 Hitachi Plasma, 11 LG LCD/Plasma, 18 Samsung LED/LCD/Plasma, 1 Thomson Plasma, 1 Atec LCD, 1 Hanspree LCD, 1 Xerox LCD, 1 Harwa LCD, 2 Proview LCD, 2 Hyundai LCD, 1 "Onn" LCD, 1 Grundig LCD, 1 Dell LCD, 1 iiyama LCD, 1 Acer LED, 1 Logik LCD, 1 Baird (China) LCD, 6 Bush LCDs, 22 Vestel LCDs (Best->Worst)
tom66 is offline   Reply With Quote
Old 11-12-2012, 09:40 AM   #7
marlboroa
Member
 
Join Date: Jul 2012
City & State: wichita falls TX
My Country: USA
I'm a: Knowledge Seeker
Posts: 52
Default Re: VIZIO VX37L No picture or sound.

I retested it and its 3.22 still. I know theses are all adjustable regulators but i dont think i have any laying around. I do have a few A1-AS1117L but cant find a data sheet to see if they will work.
marlboroa is offline   Reply With Quote
Old 11-12-2012, 10:34 AM   #8
tom66
EVs Rule
 
tom66's Avatar
 
Join Date: Apr 2011
City & State: Leeds
My Country: UK
Line Voltage: 230Vac 50Hz
I'm a: Professional Tech
Posts: 32,373
Default Re: VIZIO VX37L No picture or sound.

If they do not have -33 after them or similar they may be adjustable but why take the risk? You could burn the main board due to over voltage. Digikey has voltage regulators for cheap:

http://www.digikey.com/product-detai...4-1-ND/1217057
tom66 is offline   Reply With Quote
Old 11-12-2012, 11:01 AM   #9
MisterD
Badcaps Veteran
 
Join Date: Oct 2012
City & State: Illinois
My Country: United States
I'm a: Knowledge Seeker
Posts: 592
Default Re: VIZIO VX37L No picture or sound.

I replaced U7 and U33 both on a 42" Vizio, had low output voltage on U7 and U33 has a high failure rate.. both were same part#, I bought them from Digikey and even got extras since they were so cheap. After replacing them the TV now powers on and works fine.
MisterD is offline   Reply With Quote
Old 11-12-2012, 11:21 AM   #11
tom66
EVs Rule
 
tom66's Avatar
 
Join Date: Apr 2011
City & State: Leeds
My Country: UK
Line Voltage: 230Vac 50Hz
I'm a: Professional Tech
Posts: 32,373
Default Re: VIZIO VX37L No picture or sound.

And shipping is under $3 in continental US, I believe.
tom66 is offline   Reply With Quote
Old 11-13-2012, 10:38 AM   #12
Trackstar23
New Member
 
Join Date: Mar 2010
City & State: Chandler, AZ
My Country: United States
Line Voltage: 120VAC 60Hz
I'm a: Knowledge Seeker
Posts: 6
Default Re: VIZIO VX37L No picture or sound.

Quote:
Originally Posted by MisterD View Post
I replaced U7 and U33 both on a 42" Vizio, had low output voltage on U7 and U33 has a high failure rate.. both were same part#, I bought them from Digikey and even got extras since they were so cheap. After replacing them the TV now powers on and works fine.
Had the same happen with another 42 inch vizio (vw42l) and ended up doing the same thing after it still had issues after replacing u33. Been working 3 months now.
Trackstar23 is offline   Reply With Quote
Old 11-22-2012, 02:04 PM   #13
marlboroa
Member
 
Join Date: Jul 2012
City & State: wichita falls TX
My Country: USA
I'm a: Knowledge Seeker
Posts: 52
Default Re: VIZIO VX37L No picture or sound.

Fixed. Replaced U33 and U7
marlboroa is offline   Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump



Badcaps.net Technical Forums 2003 - 2022
Powered by vBulletin ®
Copyright ©2000 - 2022, Jelsoft Enterprises Ltd.
All times are GMT -6. The time now is 02:32 PM.
Did you find this forum helpful?