vizio gv42l dead please help

[budm]

Re: vizio gv42l dead please help

Those on my link are what I stock for repair, I order enough so make it worth the shipping charge. It will be good idea to have all of them if you do plan to work on more Vizio TV. It is up to you.

[j0gigs]

Re: vizio gv42l dead please help

Budm,

If I were to order all the regulators, can you help me to make sure I order the correct ones?

u6, abf601, ?
u4, abf601, ?
u8, abf601, ?
u5, amc1117 / f0615j, = adjustable
u10, 6e5l / 17-18l = 1.8v fixed
u9, 6e5l / 17-18L, = 1.8v fixed
u7, 6e5l / 17-18L, = 1.8v fixed
u16, 6e5l / 17-18L, = 1.8v fixed

Du2, abf601, = ?
du3, 6d1l / 17-25L, = 1.8v fixed
du4, amc1117 / f0615j, = adjustable
du1, 7805ct / rjn539g, in = ?


I am not sure what the abf601 regulators or the 7805ct regulator is.

I'd rather order them all just in case the u5 is not the only bad one. The regulators are cheap enough. It's the shipping that's expensive.

[j0gigs]

Re: vizio gv42l dead please help

Budm,

Thanks for all your help. U5 fixed it.

[budm]

Re: vizio gv42l dead please help

Great news!
Can you please post the readings of all the regulators again so it will help other people with the same problem and same board as you have?

[j0gigs]

Re: vizio gv42l dead please help

I put the tv back together. I will have to get some time to take it apart again.

[j13]

Re: vizio gv42l dead please help

I have a Vizio GV42L and have tested all the regulators and my DU4 regulator is an AMC1117- F0646J and it tested at In=3.3v Out=0.62v grnd = 0.00. All others tested much higher on the out. Would you suspect that this regulator is bad?

Thanks,

[budm]

Re: vizio gv42l dead please help

That is not right, the minimum output will be 1.25V. Check the resistance between the output pin and Gnd to make sure it is not the load that is causing the output to be low, but more likely to be bad reg.

[zape]

Re: vizio gv42l dead please help

Sorry to bump this old thread.
I came around this TV and found out that PSU wont turn on. I only get 5v stand-by.

I checked the transformer and it appears to have damaged primary coil (and no connectivity) see photo attached
I guess there is no way to fix this

So my question is: My PSU has part number 0500-0507-0410. Can it be replaced with P/N 0500-0507-0331 (which looks the same but much cheaper on ebay)?

[budm]

Re: vizio gv42l dead please help

Did you verify if you do have the >2V at PS-ON pin to turn on the rest of the power supply on?
I doubt that you have open winding for that transformer, look at the size of the wires.
Show us where you tested the transformer pins.

http://www.shopjimmy.com/vizio-0500-...upply-unit.htm

[zape]

Re: vizio gv42l dead please help

No I did not verify the PS-on
There is no connectivity between pins 6 and 4 (same with 6 and 1, but 1-4 is OK), photo attached

[budm]

Re: vizio gv42l dead please help

Primary has only winding between pin 1 and 4, it is driven by half-bridge circuit, pin 1 is connected to the DC BLOCKER/COUPLING cap to GND, Pin 4 is connected to the center connection of the two power MOSFETs. The upper part of the bridge is Q601, the lower part of the bridge is Q602. The PFC Boosted Voltage is fed to the Drain pin of Q601 through fusible resistors R805, 806 which are connected in parallel. the Source pin of Q602 is connected to GND. Pin 6 is not used, it just a blank pin, it is used to supporting the transformer to the circuit board, common practice, That transformer form factor can be used to make many versions of the transformer I.E. one may required to have primary winding with center tap so all 3 pins will be needed.
If there is no PS-ON the PFC Voltage booster will not be on and you will not get the circuit that drive the transformer to function to get the 12V and the 24V output. I would check and see if you have PS-ON or not and if you do then the DCV between the two legs of the main filter cap (big cap with 450VDC rating) should be 380~400Vdc due to PFC is now turned on because of the PS-ON is present.
So check to see if PS-ON is present or not, if not then more likely you have bad regulator IC/IC's on the main board. Also check all the fuses on the main board.

May be you should read this: https://www.badcaps.net/forum/showthread.php?t=25810

Learning about half-bridge transformer driver:
https://cdn.badcaps-static.com/pdfs/...99120f3b33.pdf
LLC-HB topology

[zape]

Re: vizio gv42l dead please help

PS-ON is 0v
Two 3A Fuses on the Main board are good. How do I check the regulator IC/IC's on the main board?

Not sure if this helps but shortly after powering up I hear some relay click on the PSU and big cap voltage is 160V. Visio logo lights up.
If I disconnect the main board from the PSU I hear no relay click but the big cap still reads 160v.

[budm]

Re: vizio gv42l dead please help

Read reply post #3 of this thread "vizio gv42l dead please help". See how OP report the readings in format that is easy for us to understand.
Also read this one:
https://www.badcaps.net/forum/showth...999#post300999

[zape]

Re: vizio gv42l dead please help

here is some readings from the ICs:

Chip, Part#, ADJ pin, Out pin, In
U7 AMC1117 0 0 0
U9 K1117S15 0 0 0
U33 AMC1117 0 0 0.02
U8 AMC1117 2.06 3.31 5.18
U2 AMC1117 0.04 0.06 0.02

Diodes and transistors around seem to be good

[budm]

Re: vizio gv42l dead please help

Too many missing Voltages feeding the input pins.
If you look at U8 which has an output of 3.3V, as you can see, the output pin (big tab/center pin) is connected to very small inductor L12; check and se if you are getting 3.3Vat both ends of that inductor or not, also see if another end of that inductor goes to, it should go to the input pin of one or more of other 1117 regulator ICs.

[zape]

Re: vizio gv42l dead please help

L12 is good, looking at the traces I think this IC is only used to drive the PS-ON PSU signal.
Trying to find out how other ICs are supposed to be fed.
Any chance to get a schematics diagram of this board?

[zape]

Re: vizio gv42l dead please help

OK I figured out that U7 and U9 are fed by U33
U33 and U2 are fed by another IC U1 (4953gm) which is basically a Power mosfet
U1 source is fed by +5vsb (reads 5.18v)
The gate pin of the U1 reads 4.79v
The conclusion is U1 is dead.

The question is: can I just short the source and the drain pins of the U1 just to test if TV will turn on?

[budm]

Re: vizio gv42l dead please help

Since U1 is the P-CH MOSFET (Souce pin is fed by b+), that means the Gate Voltage has to be 2~4V below the Source Voltage for the U1 to be biased on. You can force on that U1 by grounding the Gate pin via 100 Ohms resistor.
You should find out what the Gate pin is connected to so you know what is driving the Gate pin.

[zape]

Re: vizio gv42l dead please help

looks like the control goes from the BGA chip.
Here is a diagram with some voltage readings

[zape]

Re: vizio gv42l dead please help

So I tried to ground the base of the Q3 and it turned the U1 on and eventually powered up the other ICs. So this part appears to be working as designed.
It did not turn on the PS-ON though.
Any ideas?