Fun project Vizio GV42L Dead

[nintari]

Hi all new to the forums and man am I excited to be here I've always been in to taking things apart, learning how they tick and getting things to work when broken, as well as a slew of other DIY projects.

I'm a bit late to the game in learning about electronics in our now Throw it away mentality society but that doesn't stop me from tinkering.

After several other successful repairs I have a new project, a Vizio GV42L I picked up from goodwill for $25. I'm in the process of troubleshooting it now and have the service manual for it.

Symptoms: TV when plugged in and power button is pressed I hear a relay click but I am not getting any backlight or standby LEDs to light up.

Troubleshooting thusfar: I have taken a multi-meter to the power supply and verified fuses are fine and proper voltages are being put out for the 24V, 5V and 12V lines. Fuses on Mainboard seem to be good. Walking through the service manual on the DC-DC circuit I have got to U5 not reading 1.8V but only .8V it is a AMC1117 and from reading here it appears the direct replacement is:
1.8V Fixed:
http://www.digikey.com/product-detai...SCT-ND/1967216

I'm going to place the order today for it and then move on to the next areas.



Just keeping a log and of course looking for any advice or tips as I go along.

[nintari]

Re: Fun project Vizio GV42L Dead

Full part number is AMC1117 F0615J

is this potentially a variable one since it does not have the -1.8 on the AMC1117?

Also something a bit confusing... the DC-DC block digram has one section that says test U8, is output voltage 3.3V, which it is...then the next section says test U7,U8, U10 is the output voltage 1.8V....well... U8 is 3.3... should it be 1.8 or 3.3V??? Gotta love good documentation.

[mariushm]

Re: Fun project Vizio GV42L Dead

If it doesn't have -18 or -33 or -25 at the end, it's the adjustable version of the regulator.

The two resistors near the pins (r33 and r34) set the actual voltage with a formula that's something like 1.25 x ( 1 + r2/r1) where r1 and r2 are the two resistors

I remember seeing a video where one such regulator was supposed to output 1.2v but it was broken. I can't tell you if the regulator in the picture is supposed to be 1.2v but you could measure the resistors and figure it out.

[martyparish]

Re: Fun project Vizio GV42L Dead

You may be on to something, see here:

https://www.badcaps.net/forum/showth...t=20975&page=2

budm says "On the adjustable regulator, the voltage between pin 1 and pin 2 should always be 1.25V (this is the ref voltage)."

[tom66]

Re: Fun project Vizio GV42L Dead

The voltage between the VOUT and ADJ pins should measure 1.25V or thereabouts (+/-2% tolerance is typical for these devices, so 1.22V to 1.28V.)

If this is not being measured check the VIN-VOUT difference is more than 1V. If it's not, consider the other regulators that feed it -- they may be faulty.

[nintari]

Re: Fun project Vizio GV42L Dead

tom66:

Voltage between VOUT and ADJ shows .508V

VIN: 3.33V
VOUT: .887V

I happened to have a voltage regulator here on a sacrificial board that is part number AMS1117 0450... looking at the data sheets it seems this would be a good part to swap out with....

[mariushm]

Re: Fun project Vizio GV42L Dead

Yes, it will work... 1117 is a generic voltage regulator, made by lots of companies.

[tom66]

Re: Fun project Vizio GV42L Dead

tom66:

Voltage between VOUT and ADJ shows .508V

VIN: 3.33V
VOUT: .887V

I happened to have a voltage regulator here on a sacrificial board that is part number AMS1117 0450... looking at the data sheets it seems this would be a good part to swap out with....

Definitely faulty, and it's got a good supply voltage, so it's at fault. Replace that with the spare regulator & you should be good to go.

[nintari]

Re: Fun project Vizio GV42L Dead

I'm incredibly disappointed now..... I replaced u5 with the VR from the spare circuit I had here and it works

I say I'm disappointed because it was too quick....now I need to find something else to fix I think a friend of mine said he had a Panasonic plasma that was dead....

Items repaired this year:
LG 50" plasma Lower Y Bufferboard bad
PS3 dead laser, replaced
Vizio GV42L U5 bad

I've always wanted to do more stuff like this but never had the equipment to do so thank god for lucky finds at yard sales lol (picked up a very nice metcal soldering station and lots of tools dirt cheap!). What started me last year officially was a Denon 2808CI receiver I bought of ebay and the seller didn't pack well (I was refunded and told to keep it)... the front faceplate circuit board was destroyed in several places and I had to stitch it back together and after a few weeks of re-tracing I got it working!!

now about that panny plasma.....

[martyparish]

Re: Fun project Vizio GV42L Dead

Nice ending! I'm hoping to have similar results on my Vizio L37HDTV10A.

[retiredcaps]

Re: Fun project Vizio GV42L Dead

I say I'm disappointed because it was too quick....now I need to find something else to fix

Let me make a proposal that you should seriously consider.

There are very few regulars here at badcaps.net. If you are looking for a challenge, participate in many threads and try to help others with troubleshooting advice.

I think you will find virtual repairs more challenging and potentially rewarding than physical repairs.

[nintari]

Re: Fun project Vizio GV42L Dead

Huzzah!

Still problems lol. Front LED isn't lighting up under Vizio logo and IR not receiving remote codes. Opening back up to see if it is just a loose connection

I plan on browsing once in a while trying to learn what I can, I have always done well with hands on tough so makes it tougher for someone with no real experience... but that will come with time!

[nintari]

Re: Fun project Vizio GV42L Dead

whomever worked on this before they ditched it at goodwill did a number, the LED for the front is gone only the wires remain, the IR receiver was flipped backwards .... go figure.

Testing now with a blu-ray player.

[MisterD]

Re: Fun project Vizio GV42L Dead

I'm going to my local Goodwill tomorrow, hope to find a non-working LCD TV there.

[tieny]

Re: Fun project Vizio GV42L Dead

Ah, I worked on this same exact TV before. It was a pain getting it open... since it opens from the front and you don't need to remove the screws yet. Its just stuck on with its plastic hinges. But once I finally got it off what do you know..., the LED and IR was hooked with it, so I ripped off the LED light wires... but luckily saw it in time so I didn't take the IR with it lol.

Tried to solder back the wires, but eh... didn't turn out too good, so just left it off. :p

[GR3Y5H3ART]

Re: Fun project Vizio GV42L Dead

sry to bump up an old thread but if this can help someone open up a set w/out screws

they are easy to open with one item, a plastic card, i.e. credit card or something w/that thickness, stick it in, then literally just run it all the way across


found this video while trying to repair something else on Youtube and it helped so much...on another monitor, i could see where someone tried to open it w/a flathead and then gave up on it, this video has saved me lots of time:

https://www.youtube.com/watch?v=dmw-lad_i-g

[ecking767]

Re: Fun project Vizio GV42L Dead

The fun isn't over yet, I will recap the power supply since this TV is over 5 years old. this will prevent future failure.