VIZIO VO42L fhdtv10a No picture again.

[the loner]

Hi everyone, my first post.

I have a broken Vizio VO42L television again.
I have searched through the topics of this model and I have successfully (well only for about 20 minutes ) repaired my television due to the main inverter board had a 2 blown out caps and 1 leg on the ic was burnt off (could have been 2, I can't remember now)

I don't have professional equipment to do proper testing but I do have a digital multimeter, soldering station, hot air welder (Aoyue 968) and reflow/reball station that I fix xbox's with (sorry getting off topic).
I had replaced the boards last night, (I plan to replace the defective regulators and ic on the first blown board soon).

I received the new/used boards from a supplier in China and it worked fine for the 20 or so minutes that it was on, I don't know how long because I just left the room with the tv on and went back later to find no display.
I'll try to explain what I have done.

With the new boards, there is no popped caps, no ic damage that I can visually see, nothing burnt that I can see, but there are a couple of smd's that have been soldered crooked. The MOSFET's read 9.01k ohms on the master board and 8.9 on the slave board so I believe the MOSFET's are ok.

The fuses (main one 10A) seem to be ok, tested ok for continuity, the caps look ok but I think they are of poor quality sam young 105 deg., 35v 380 uF.

Plug the ac cord in, the Vizio emits orange (stand by)
Push power, Vizio emits white, but no picture (black screen).

I have done the 24V light test to see if the power supply is failing, but it seems fine with little voltage loss. Lights come on when I push power, go off when I turn the tv off.

Ac plugged in stand by mode...
Pson 0.03v
12 0v
5vsb 5.17v
A 0v
B 0.02v
AC plugged in and on (white Vizio icon)
Pson 3.27v
12 0v
5vsb 5.15v
A 2.91v
B 4.71v

I just don't want to replace (well it will be a repair this time, my wife can watch tv in the other room) the cards, but I don't see any physical damage this time, not like the last time when I smelt smoke and I knew exactly where to go (fix the problem).

Any other trouble shooting that I have missed would be greatly appreciated if there is something that I have missed working with the tools that I have.

The last picture is probably the worst for lighting. Go figure.

[the loner]

Re: VIZIO VO42L fhdtv10a No picture again.

Nobody out there to help me?
I'm not asking to be spoon fed, just point me in the right direction.
Do I have bad inverter cards?
Any help would be great.

[budm]

Re: VIZIO VO42L fhdtv10a No picture again.

So which one is the inverter boards you are usinging? The one with two yellow transformers looks like the original, the ones with black transformer are the new boards?
At this point the Main board is sending correct signals to the Power supply and the inverter board and same for the 24v, so you do have inverter problem.
And just to sure, you did put all the mounting screws back on the inverter boards? They are not shown in the pictures.

[the loner]

Re: VIZIO VO42L fhdtv10a No picture again.

Sorry for not being clear on the pictures.
The yellow transformers are the old ones, the black ones are the replacements.

I did put the brackets back on top of the boards (I did not take pictures of the new inverters installed, but brackets were put back in) but I had to use the single (blue) wire to connect the new(used) boards since the plug was different than what was originally on the original boards. Will this make a difference to supply power to the screen since the original inverter boards were 2 wire?
Also, the big main capacitor on the power supply reads 164v on stand by, and 402v when on (Vizio logo is white)

I checked the new inverter boards for resistance across the mosfet's and they read around 8.9k - 9.02k ohms which to me (I'm no expert, I just want to clarify this, just a DIY) seems within specs, and the caps do not look defective or popped, but I do not know how to properly test them, and the ic does not look damaged.

Is this just a cheap board from China where I should ask for my money back?
I think so. It's just frustrating that someone with my limited knowledge can look through these threads, make the correct diagnosis, repair the problem, and literally, 20 minuets later, the same problem, and then think, well maybe this wasn't the problem.

[budm]

Re: VIZIO VO42L fhdtv10a No picture again.

Those two wires are high voltage wires, I would say yes other wise the Vizio would have used just one wire to save money.
Do you have P/N of the old board and the new board? Also the P/N of the LCD panel as printed on the lable. I can do some research on the inverter board and the LCD panel to see how the lamp's wires are connected/used.

[the loner]

Re: VIZIO VO42L fhdtv10a No picture again.

If I attach the other wire to both of the inverters, will they come back to life? Maybe?
Right now, they will not boot up/power up. It's as they are defective again like the original, but the original inverter had a blown ic and popped cap.

[the loner]

Re: VIZIO VO42L fhdtv10a No picture again.

LC420WU5 6632L-0470A OEM Master
6632L-0471A OEM Slave

LC420WUN-SCD1 6632L-0620A Replacement Master
6632L-0621A Replacement Slave

The LG inverter modification has NOT been done either.

Give me a few minutes and I'll get the number off of the lcd screen.

I'm not sure if these pictures will help, but they are the original inverters and where the wires go. The new inverters would plug into the middle pin and the pin on the top was not connected.

[Dgtech]

Re: VIZIO VO42L fhdtv10a No picture again.

I have to chime in and say that I personally would not have tried a different type of inverter boards. Since you do have the original slave board verify first that the resistances across the mosfets show 8.5k ohms. This should be the same on the master but since the IC is blown it wont measure correctly. Replace the chip and the caps on the master and you should be ok. Just search for the chip on ebay and you should be ok using your soldering station.

[the loner]

Re: VIZIO VO42L fhdtv10a No picture again.

The old slave board shows resistance from 8.21k to 8.43k ohms. The new boards show 8.96k ohms on the slave, and 9.02k ohms on the master.

I have taken pictures of the lcd screen to make it easier.

[budm]

Re: VIZIO VO42L fhdtv10a No picture again.

Can you take the resistance reading on the old inverter board lamp connector pin to see if the two pins are tied together?
Here is the spec sheet for the LCD panel:
https://cdn.badcaps-static.com/pdfs/...eaa88e8a02.pdf
It does not show the lamp setup.
I look up shopjimmy, your new board is not listed as the replacement for the 6632L-0470A/1A.
http://www.shopjimmy.com/lg-6632l-06...t-inverter.htm
http://www.shopjimmy.com/lg-6632l-06...t-inverter.htm

Original:
http://www.shopjimmy.com/lg-6632l-04...ter-master.htm
http://www.shopjimmy.com/lg-philips-...rter-slave.htm

[the loner]

Re: VIZIO VO42L fhdtv10a No picture again.

I'm not 100% sure I understand what your looking for, but I have taken a picture of what I think your looking for with my dmm set to 200 ohms.
It reads 0.5 ohms.

[budm]

Re: VIZIO VO42L fhdtv10a No picture again.

I want to know if the two pin are connected together to figure out if one pin is for supply and one for the return pin for the lamps.
At this point I cannot trust that the replacement boards are made for this panel.

[the loner]

Re: VIZIO VO42L fhdtv10a No picture again.

Well, that's nice. Spent $100 for nothing. (I'm not mad or upset at you budm, just tired of being lied to)
I really appreciate everything that you and Dgtech have done for me.
Well, I guess I'm on the war path now to get my money back and order the correct boards, not something that may be compatible.

Thanks for all your help.

[budm]

Re: VIZIO VO42L fhdtv10a No picture again.

At this point we cannot do much until you get the same model boards install first, you can tell the seller that the replacements do not have the same connector as the original one and you will want to make modification to the connectors. Good luck and hope you can get the money back.

[Dgtech]

Re: VIZIO VO42L fhdtv10a No picture again.

What I have been doing with sets like these is I've been changing the inverter chips if I don't read 8.5K across all four mosfets. What I mean is that I've had a set where one read 8.25k and I let it stay and it blew about 4 months later. The caps on both boards I would change out as well just to keep from going back into this set in the future.

I hope you can get your money back.

[the loner]

Re: VIZIO VO42L fhdtv10a No picture again.

Just a quick update for everyone who is interested. I did not get my money back and the seller has stopped responding to my messages now. I have stepped it up and now have the credit card company involved.
They have suggested to send back the defective/wrong/incompatible cards to the seller, only problem is that I threw out the package with the address.
Oh well, its a call to DHL on monday and see if I can get the address from them off of the waybill. Funny, now that I think about it, I don't remember having an invoice in the box. Funny....

[Dgtech]

Re: VIZIO VO42L fhdtv10a No picture again.

Just chalk that one up to "lesson learned" and move on. Some fights aren't worth fighting.

[the loner]

Re: VIZIO VO42L fhdtv10a No picture again.

Just to update the problem I had with the tv, (yes I know it has been a long time since I have been back) but I have installed the correct inverter cards into the tv and everything works like new again.
Thanks to everyone for the help and info.
Now it's time to start another project that I need help with.

[budm]

Re: VIZIO VO42L fhdtv10a No picture again.

Glad hear it is working again.