vizio gv42l dead please help

[j0gigs]

Hi, I have a vizio gv42l hdtv that is dead. When I plug it in, the orange vizio led lights up orange and after 5-10 secs dims, but stays on orange. When I press the power button, nothing happens, no clicks nothing.

I looked at the caps on the power supply and all look fine, no bulges or leaking caps. I checked all the fuses on the power supply and main board and all are fine.

I am getting 5 volts on all the 5v pins on the power supply and main board, but not 12 or 24 volts on anything.

I tried unplugging the backlight boards, the audio connector on the main board, the ir board and the t-con board and still nothing.

I am not sure where to go from here. My guess is its the main board. I would like to try to fix the main board if I can. a replacement is 125 and I really don't want to spend that much on this old tv. I am guessing its one of the power regulators, but im not sure exactly what they are supposed to be reading for voltage.

I am by no means a tv repair person, however I have been able to fix 5 sets so far by reading the forums here and really enjoy fixing these things with the help of the awesome members on this forum.

I have attached pictures of the boards. Please help. Thanks in advance.

[budm]

Re: vizio gv42l dead please help

Take the voltage readings of all the Voltage regulators and report the readings of each one in the format as shown in this thread.
https://www.badcaps.net/forum/showth...999#post300999

[j0gigs]

Re: vizio gv42l dead please help

Hi Budm, thanks for the reply. Here are the results of my testing:

Chip, Part#, ADJ pin, Out pin, In pin
u6, abf601, 0, 3.29, 5.15
u4, abf601, 0, 3.29, 5.15
u8, abf601, 0, .016, .466
u5, amc1117 / f0615j, 0, .946, 3.292
u10, 6e5l / 17-18L, 0,0,.016
u9, 6e5l / 17-18L, 0,0,.016
u7, 6e5l / 17-18L, 0,0,.016
u16, 6e5l / 17-18L, 0,0,.424

Du2, abf601, 0, .260, .466
du3, 6d1l / 17-25L, 0, 0, .448
du4, amc1117 / f0615j, 0, 0, .754


du1, 7805ct / rjn539g, in = .525, gnd = 0, out = 0

I hope this makes sense. Please let me know what you think.

Thanks

[budm]

Re: vizio gv42l dead please help

What is the full model of this TV, there are more than one GV42L.
It looks like you did not get all the regulators,
https://www.badcaps.net/forum/showth...O+GV42L&page=4

[j0gigs]

Re: vizio gv42l dead please help

it is model gv42L HDTV.

I believe there are 2 different models of the gv42l. I read that post and chip u33 on my main board looks like a tiny chip with 16 legs on it. I have seen 2 different looking main boards. My main board is the one without the heatsinks on the main chips.

I hope this helps.

[budm]

Re: vizio gv42l dead please help

We need to find out which version of the main board you have.
Look real close at you board to see which one you have:
http://www.shopjimmy.com/catalogsear...izio+GV42LHDTV
Look at those numbers after VIZIO 3642-??????????????? to see the one that belongs to your TV.

[j0gigs]

Re: vizio gv42l dead please help

I have the 3642-0012-0150 (3a) main board.

[budm]

Re: vizio gv42l dead please help

Chip, Part#, ADJ pin, Out pin, In pin
u6, abf601, 0, 3.29, 5.15: OK
u4, abf601, 0, 3.29, 5.15: OK
u8, abf601, 0, .016, .466: Bad, input is too low
u5, amc1117 / f0615j, 0, .946, 3.292:Bad Regulator, the output should be 1.25V
u10, 6e5l / 17-18L, 0,0,.016: Bad, this is 1.8V reg, the input is too low
u9, 6e5l / 17-18L, 0,0,.016: Bad, this is 1.8V reg, the input is too low
u7, 6e5l / 17-18L, 0,0,.016: Bad, this is 1.8V reg, the input is too low
u16, 6e5l / 17-18L, 0,0,.424: Bad, this is 1.8V reg, the input is too low

Du2, abf601, 0, .260, .466: Bad, Input is too low
du3, 6d1l / 17-25L, 0, 0, .448: Bad, input is too low
du4, amc1117 / f0615j, 0, 0, .754: Bad, input is too low.
du1, 7805ct / rjn539g, in = .525, gnd = 0, out = 0: Bad, input is too low, the input should be 12V.

So one regulator U5 is bad.
The other with very low input voltage of around 0.5V (0.466, 0.448, 0.754), we need to find out where that 0.5V is coming from, it should be a lot higher than that.

[j0gigs]

Re: vizio gv42l dead please help

How do I proceed? Do you think replacing u5 and u8 will fix my problem or do I have something else going on? Thanks

[budm]

Re: vizio gv42l dead please help

I would replace U5 first. One thing is bugging me on those regulators with low input voltages, you need to find out if the input pin of those ICs are connected together and Voltage is supplied by the same source or not.

[j0gigs]

Re: vizio gv42l dead please help

Do I do a continuity test to check that? Do I buy the regulators from digikey or mouser? I could not find a regulator on there for the amf601 ones. I'm not sure if that's the right part number to search for or if I need to cross reference it somewhere.

[budm]

Re: vizio gv42l dead please help

"amf601" I do not believe that is the P/N of the regulator. There should be more than one line of printing on the body.
Most regulators are 1117 series which you can get from Digikey.
Can you get good closed up pictures of U5, U6? I need to verify the P/N and need to find out if U5 is fixed or adjustable type.

These are what I use for VIZIO repairs:
https://www.badcaps.net/forum/showpo...91&postcount=7

[j0gigs]

Re: vizio gv42l dead please help

Budm, Here are the close up pictures of u5 and u6. I checked the chips again. u6 only has one line on it and does say abf601. u5 is also amc1117 on the first line and f0615j on the second line.

[budm]

Re: vizio gv42l dead please help

"u5, amc1117 / f0615j, 0, .946, 3.292
u10, 6e5l / 17-18L, 0,0,.016
u9, 6e5l / 17-18L, 0,0,.016"

Can you verify the U9 and U10, I can see resistor network on U5, U9, and U10 which the network is used for setting the output voltage of the variable regulator type IC, but you have indicated that U9 and U10 has 17-18L label on them which indicate U9 and U10 as 1.8V Fixed OUTPUT Regulators.
If you look at pin 1 of the regulator, if it is fixed output regulator, pin 1 will be tied directly to ground, if it is variable output regulator there will be resistor between pin 1 and Ground and another resistor between pin 1 and pin 2 (output pin) to set the output voltage.
I would say that those small 3-pin regulators are 1117 series but we must verify the number and look at one with pin 1 connected to ground to find out if what the fixed voltage ones are rated at.

[withalligators]

Re: vizio gv42l dead please help

I worked on one of these a while ago. It turns out on the main board, there is a set of three pico fuses, and the 1.5a one on the left goes bad a lot. I bought a fuse holder and bunch of fuses from digikey. It's blown once since then, and I've read it's not a bad idea to replace it with a 2a one. The regulators can also go bad.
See:
https://www.youtube.com/watch?v=qC9FEZ78-qM

[j0gigs]

Re: vizio gv42l dead please help

Budm,

I checked those regulators again. The labels on the chips are correct. U9 and u10 are as I originally posted. For some reason u5 has changed. The readings I got today are adj= .336, out= .939 and in= 3.293. I wonder why that one changed.


Withalligators,

I saw that video. My main board only has 2 fuses and both are good.

[budm]

Re: vizio gv42l dead please help

U5 was the bad regulator as I indicated earlier, the output voltage should always be = to 1.25V ref + the voltage reading on pin 1 for 1117 adjustable regulator, so if pin 1 has 0.366, then the output should be = to 1.25 + 0.366 = around 1.5V. I would replace this U5 first.

[j0gigs]

Re: vizio gv42l dead please help

Would I use the adjustable regulator that you linked to from digikey?

[budm]

Re: vizio gv42l dead please help

U5 is adjustable, if it is fixed, then there will be no voltage on pin 1 since fixed output will have pin 1 tied to ground. The one in my links are what I stock for repair works. You should order more than one.

[j0gigs]

Re: vizio gv42l dead please help

What do you think I should order? Are all 1117 adjustable voltage regulators the same or are there different ones? Should I order any of the other regulators?