Vizio VW42l t-con repair

[david37g]

Best forum I have found.
After following the threads on Vizio42L "No Sound and No Picture" I have repaired my TV. The problem turned out to be a bad T-Con which I replaced. After checking all the main board voltages, which were okay and since I had a backlight( the inverters were okay) I replaced the T-Con and it worked.

There is a bad LDO (U9) on the bad T-Con which I would like to replace, to see if it will work.
Numbers on it are R79164A and 15PG9H30W. It is the same size as U33 on the main board. I can not find any reference to these number at Mouser or Digi-Key. I checked the voltages on the good T-Con an they are 3.3,1.6 and 0. The same as on U8 on the main board, but U8 is a fixed output. I think the "A" in the number mean "Auto" but I am not sure.

Would an LD1117a Same as U33 work in this application? The footprint is the same.

Thanks for a good forum, David

[cadiman]

Re: Vizio VW42l t-con repair

When you remove this regulator check to make sure you have an input voltage. When these fail they go low. 3.3 will be like 2.7volts or so. The board fuse may be fine in your case.

I am not a cross reference but I have used the 1117 regulators and I think they were 3.3 volt in my case. I had pulled them from working boards running at 3.3 volt.

[david37g]

Re: Vizio VW42l t-con repair

After replacing U-9 on the T-Con board with an ACM1117 I now have 1.2 volt out (not 1.6 as I originally posted), the same as my good board, however the lcd still does not go dark blue. I have also found that the original U-9 was a RT9164a not a R79164a. Digi-Key has the RT9164a. Will look further for what the problem is as time permitts.

[budm]

Re: Vizio VW42l t-con repair

If there are two resistors network at one of the pin, then that will be adjustable regulator. if one pin is grounded, then that will be fixed output. If you see something like 1117 -33, the 33 will represent 3.3v, without the number then it will be adjustable type.
See example of how they are used.

[david37g]

Re: Vizio VW42l t-con repair

Replaced U-9 with a new RT9164 from Digi-Key. Gives the same output voltage(1.2v) as the AMC1117. Still no picture from this board. I am now trying to trace the output circuit.

[tom66]

Re: Vizio VW42l t-con repair

What is the input voltage to the regulator? (pin 3)

[david37g]

Re: Vizio VW42l t-con repair

Input voltage is 3.0.

[david37g]

Re: Vizio VW42l t-con repair

I have traced the output of U-9 to the LG Philips LCD chip. There is an open circuit on the bad board that is closed on the good board.
The numbers on the chip are: R8A01028FA
DINIL-0058A
728108
It is an 80 pin. I have not been able to locate a source for this chip.