Vizio VW42LFHDTV10...Brother Mikes TV...

[Paul J]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

I had to go back and re-read some posts about measuring pin 1 2 3, so I hope I got this right, the U9 Pin 1 value seems odd, but here goes.

U33 1.3 2.1 5.17

U2 2.05 3.31 5.17

U7 0.02 1.04 2.10

U8 2.07 3.32 5.19

U9 0.00 1.22 2.10

[Paul J]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Hello, I am Paul, a new member. Have been reading the forums for a couple days. I am looking at my mothers VW42LHDTV10A with main board
3642-0262-0150(3B)
CSD:3642-0192-0395
She has been battling hemolytic anemia for several months and the tv has become much more important for entertainment. My soldering skills are not great but I have done some on larger Heathkit type projects. I am satisfied my power supply is ok and master inverter glows blue led for a couple seconds the same as my own vizio. Her tv was already repaired once under warranty but I dont know what they did. I get the orange to white vizio logo but no menu, backlights are on. (won't power off) I'm getting ready to try and measure voltages on the U33 amc1117 I believe, but not sure on the order to measure. Stuff is so small for my eyes! I have attached some pics and will post the voltages of U33 and am hopng someone can tell me if they are correct. All fuses check ok in that the voltage is the same on both sides. Thanks for a very interesting forum, I don't know that I'll be buying anymore Vizio's but I think this may be the most troublesome model.

[PlainBill]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Alas, I have a VW42L that I need assistance with. I have read thread after thread in regard to testing the various regulators and think that I understand what to do but I feel as though I am not even getting power far enough to the main board. Please advise a good starting spot. I have downloaded the service guide from more than one location but do not have a main schematic in either .pdf

I am just unsure where to begin tracing the power. I have 5v to the 3,4,5 pins in J1 and 5v across the F1 fuse...please bear with me if I ask a dumb question but HELP..lol

The first step is to provide pictures of YOUR set. I don't trust any manufacturer to use the same boards throughout a production run. Pictures must be well lit, sharp, and at least 1000 x 1000 pixels, but not over 2000. At this point we need three pictures - one of the entire TV, one of the power supply, and one of the output connectors of the power supply showing the legend that indicates what voltage or signal is on that pin.

If you prefer to go it your own, one possible cause could be the control signal from the main board to the power supply is not going active, OR the main power supply is not turning on.

PlainBill

[jcabston]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Alas, I have a VW42L that I need assistance with. I have read thread after thread in regard to testing the various regulators and think that I understand what to do but I feel as though I am not even getting power far enough to the main board. Please advise a good starting spot. I have downloaded the service guide from more than one location but do not have a main schematic in either .pdf

I am just unsure where to begin tracing the power. I have 5v to the 3,4,5 pins in J1 and 5v across the F1 fuse...please bear with me if I ask a dumb question but HELP..lol

[PlainBill]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

PlainBill
Sorry finally got the parts but both wife and I were sick with flu too weak to do anything lol. Replaced U33 checked the votages on all again and they were all with in normal limits as listed by you we had tv to check voltages then flipped the tv upright to look at screen and there it was the "No Signal" up on the screen!! We were so Happy remote is working and everything seems to be running pretty good. We want to Thank you so much for your patience, and advice we are Grateful to your expertise!
thank you Again
Dan

Congratulations on getting it working. I know how the flu can knock you out. The last bout I had I was sick for two weeks and it took another two to get back close to normal.

PlainBill

[danejo]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

PlainBill
Sorry finally got the parts but both wife and I were sick with flu too weak to do anything lol. Replaced U33 checked the votages on all again and they were all with in normal limits as listed by you we had tv to check voltages then flipped the tv upright to look at screen and there it was the "No Signal" up on the screen!! We were so Happy remote is working and everything seems to be running pretty good. We want to Thank you so much for your patience, and advice we are Grateful to your expertise!
thank you Again
Dan

[danejo]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Just get three or four; they are inexpensive. We'll have to sort out U7 later if replacing U33 doesn't fix it.

PlainBill

Parts Ordered and shipping out today
will post when we get it replaced hopefully by Saturday!

Dan

[PlainBill]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Thank you so much for your time and i will look up the part to replace U33 and Post back the results, should we also replace U7 to be safe? or just get a few extra just incase!
thank you again
dan

Just get three or four; they are inexpensive. We'll have to sort out U7 later if replacing U33 doesn't fix it.

PlainBill

[danejo]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Thank you so much for your time and i will look up the part to replace U33 and Post back the results, should we also replace U7 to be safe? or just get a few extra just incase!
thank you again
dan

[PlainBill]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

do you think i should replace the HDMI interface also? i was going thru the other posts to find the correct part to order from Digikey just incase you said something was bad and had to go.
TY!
Dan

I wouldn't do that at this point. Research hasn't progressed to the point of positively identifying the culprit. If you wish, try to identify the IC and check availability. If it's a 40 pin TSOP that is only available in quantities of 5000 it isn't practical; even worse if it's a BGA package.

PlainBill

[danejo]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

do you think i should replace the HDMI interface also? i was going thru the other posts to find the correct part to order from Digikey just incase you said something was bad and had to go.
TY!
Dan

[PlainBill]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Hello PlainBill,
we did as you said and checked all the LDO Regulators and here are the results.U33 ,U7,U2 and U8 are AMC1117 and U9 is K1117-S15725 we use the SCrew on the circuit board for ground .
pin 1 2 3
U33 - 1.2 1.9 5.3
U2 - 2.0 3.3 5.1
U7 - 20mv .95 2.2 here the values jumping high and low when backlights went on
U8 - 2.0 3.3 5.1
U9 - 0 1.4 1.99-2.0
Your next Advice would be greatly appreciated
thank you

U33 is definitely bad. U7 is probably good, you are getting into the dropout voltage on that.

There have been follow-up reports of U33 failing after a while, probably due to excessive load. So far no-one has positively identified the cause, although the HDMI interface IC is a suspect.

PlainBill

[danejo]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Hello PlainBill,
we did as you said and checked all the LDO Regulators and here are the results.U33 ,U7,U2 and U8 are AMC1117 and U9 is K1117-S15725 we use the SCrew on the circuit board for ground .
pin 1 2 3
U33 - 1.2 1.9 5.3
U2 - 2.0 3.3 5.1
U7 - 20mv .95 2.2 here the values jumping high and low when backlights went on
U8 - 2.0 3.3 5.1
U9 - 0 1.4 1.99-2.0
Your next Advice would be greatly appreciated
thank you

[PlainBill]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Hello all, i have been reading the posts here for 3days now So very Informative! My Vizio GV42L FHDTV10a is also acting up no pic,audio can turn on but have to unplug to shut it down all lights work now wife made a list of everything to check on the main board from all the posts she read but didnt write down if the set has to be Plugged in and whether tv set should be on Could some one plz clarify before we tackle the tv.
thank you
Dan

After you have removed the back of the TV, plug the TV in, turn it on, and measure the voltages on the LDO regulators. U33 is often bad. Report the results for confirmation.

PlainBill

[danejo]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Hello all, i have been reading the posts here for 3days now So very Informative! My Vizio GV42L FHDTV10a is also acting up no pic,audio can turn on but have to unplug to shut it down all lights work now wife made a list of everything to check on the main board from all the posts she read but didnt write down if the set has to be Plugged in and whether tv set should be on Could some one plz clarify before we tackle the tv.
thank you
Dan

[GbreadMan]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Finally found the PSS at the bottom of one of the posts saying it's a GV42L. Scratch everything I said.

[retiredcaps]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

I would upload the manual but I'm not sure where.

If the pdf file is less than 9.5MB, you can use the manage attachments button below the text entry area to upload the file so it is hosted here at badcaps.net.

[GbreadMan]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

I was a Vizio TV parts swap person for a couple years; mostly performed simple board swaps but the repair vendor gave us the service manuals for all the Vizio TV's at the time.

According to the VW42L_HDTV10A manual from 061107T (6th of Nov 2007?), U8 pin-1 on the dc-dc converter should be +5v, and pin2 should be +3.3V (doesn't say anything about pin3).

However, the manual's flowchart says U5 pin2 should be around +1.2V while power switch is on (p.91)...two other chart discrepancies follow:

U6 pin2 = +1.8v (doesn't specify whether power switch should be turned on or off)
U10 pin2 = +2.6v (with power switch on)

The manual / flowcharts do not mention several components at all, including U9,U16,DU#, etc. Perhaps there's a manual somewhere for that specific PCB? Is it manufactured by LG?

I would upload the manual but I'm not sure where.

Hope this helps,
Dan

[Spetznazer]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

All right. It seems like U5 have to go. I'm gonna replace and see what gonna happen. To be continued...

[PlainBill]

Re: Vizio VW42LFHDTV10...Brother Mikes TV...

Thank you Bill for the effort to help. I decide to heat up the board with heat gun to see if it will lead me somewhere but with no luck. Set acts the same way. i downloaded service manual that says it is for the same model. Not much of info there for me but I found troubleshoot diagram for DC-DC converter so I went through checking Volts again. In a manual it says that the voltage on a pin2 of U5 must be about +1.8V (which is 1.94) also it says that pin2 of U8 also must be about +1.8v where it is about 3.3V. Either manual is wrong or board was revised and changed after manual was written. I went trough the diagram and checked all pins it was mentioned and got right data except that pin1(PWON) of J7 connector from board to PS was 4.6V and not up to 3V as in manual but that can be O'k right?.

Yes. Every design I've seen the 'power on' pin drives the base (or gate) of a transistor. The threshold is normally about 2 volts to turn on the supply. A higher voltage would not cause problems.

The information about U5, pin 2 is significant. There are three reasons that output voltage would be higher. One - a change in design - doesn't make sense. Another is that the regulator is defective. A third is that the IC that is receiving the 1.8 volts is defective. Actually, the whole design doesn't make much sense. Why use an adjustable regulator when a fixed one is available?

PlainBill