Vizio VO42L question

[tibimakai]

Re: Vizio VO42L question

I will do that. I remember measuring some low voltages, but next time I will write them down.
At the transformers I have measured 5.8V on all pins except one of them, which was 0V. I have measured only that side only.
There is a method of using the scope to see if the transformer it's working?
Holding it close to it or something like that? Or even the DMM at a certain scale?(uA)
What is weird, that I don't even have two seconds two black.
There are those A B C inputs, what should I measure at these pins?
I'm measuring at A: 2.58V, at B: 5.07V, C is not connected.
The 12V is only 11.88V, that is enough?

[tibimakai]

Re: Vizio VO42L question

Ok I have the voltages:
(tab on top and measured from right to left)
Slave board FETs:
SQ8:
5.8V
25V
5.8V

SQ9:
0V
5.8V
0V

SQ10:
5.8V
25V
5.8V

SQ11:
0V
5.8V
0V

Master inverter FETs:
MQ1:
0.22V
25V
0.22V

MQ2:
0V
0.22V
0.004V

MQ4:
0.15V
25V
0.15V

MQ5:
0V
0.15V
0.004v
How can I test the inverters?
There is a way to start them without the rest of the TV?
What kind of voltages need to be able to start?
I have 25V, 5.07 and 2,58V at the connectors.

[budm]

Re: Vizio VO42L question

Look at pin 16, per spec of the IC it is for STBY/ON-OFF, see if it changes state when BL_ON is LO and when it goes HI, I expect to see state of change at pin 16. The diagram may be close enough to troubleshoot it. I will look and see if I have the same inverter board in my spare parts box, I know I have the same bad inverter boards in my Vizio that I replace the blown IC and shorted MOSFETS, it works after that repair.

[tibimakai]

Re: Vizio VO42L question

Thanks, I will check it out in the next couple of days. I'm all over the place lately.
With this TV the problem seems to be the master and not the slave inverter.
The only problem that I have noticed is one bad FET on the master inverter.
I'm trying to finaly run those wires on that 46" Samsung to the sideports.
I have picked up an LG 42LG70, another Vizio VW42L, a Sony KDL 40W4100.
Last two are running(bad VDO on main and two ccfls were replaced).
I still have those two monitors, the Samsung 245BW and Acer MK24H to repair.
Tomorrow I think I will pick up a 42" Philips 42PFL7422D/37. So I'm rolling again, after like two very slow months.

[tibimakai]

Re: Vizio VO42L question

I had a bit of time and I managed to measure them. Both ICs had 3.85V on pin #16 when the TV had started(after the blue LED turned on, on the master inverter)

[budm]

Re: Vizio VO42L question

It does change state when the TV is off and when the TV is on?

[tibimakai]

Re: Vizio VO42L question

Yes. When it's off it's 0.004V and when it's on is 3.85V.

[budm]

Re: Vizio VO42L question

Ok, that means there is something else that stops the IC from putting out the drive to the MOSFET's. Need to look at the IC spec again to see what else should be running when pin 16 gets the turn on signal.

[tibimakai]

Re: Vizio VO42L question

budm, what would do a good TV if I don't connect one of the inverters? I have never tried it.
If let's say, the master has some issues and I just connect the slave, what will do the TV?
I will have to look over those pdf files.

[budm]

Re: Vizio VO42L question

The two Inverters work together like a push-pull setup, if one is not working, you will see the lamp will not be fully it, it will light up abot half the length of the tube then go into shutdown.

[tibimakai]

Re: Vizio VO42L question

Thanks.
So, that means that none of my inverters turn on.

[budm]

Re: Vizio VO42L question

Yes.

[tibimakai]

Re: Vizio VO42L question

How do I know if the issue is inverter related or not?
How much should be the voltage for the inverter to be able to turn on? I have 2.58V, 5.08V and the 25V.

[budm]

Re: Vizio VO42L question

The inverter needs 24V (typical) for main power, BL_ON to turn it on, Dimming (0~5V) to adjust how hard the inverter will drive the lamps, and may be an error output signal back to the main board to tell the system if the boards are functioning or not.

[ecking767]

Re: Vizio VO42L question

replace all FETS on the slave inverter board, you found one that was bad.
Becuase you don't know how one bad FET affected the other FETS.

[budm]

Re: Vizio VO42L question

When I fixed mine, I replaced all the 4 MOSFET's and the PWM IC on each boards, the master board had burnt out IC and shorted out two MOSFET's, and I do not want to wait and see when the slave board will go out later, so I did both of them and applied the mod at the same time.

[tibimakai]

Re: Vizio VO42L question

I have replaced both ICs, since none of the inverters would start and one FET on the master which was shorted.
The originals were K107(?! not sure about these numbers) and I have replaced that one with some other designation FET which comes in the Chinese kits from Ebay.
OK, I will replace all of them.
I haven't done the mod yet on any of the repaired TVs.
I always start looking for the parts, it gets confusing, takes time to get the parts and I just end up skipping the mod.

[budm]

Re: Vizio VO42L question

The FET's on my board is 2SK4075, I got the IC and the FET's from Chinese vendor.
I also replace the two caps on the board since they are known to go bad also.
http://s807.photobucket.com/albums/y...VO42LFHDTV10A/

[tibimakai]

Re: Vizio VO42L question

I have FDD8447L in the kit and that I have installed. To my knowledge it should be compatible with the stock one.
I have replaced the original capacitors as well, since the ESR was showing E=0(not sure what it means).
This afternoon, I have picked up a Samsung 225BW(supposed to have red tint, but at the moment it's working just fine) and a Philips 42PFL7422D/37(completely dead), so didn't have time to replace the FETs.

[tibimakai]

Re: Vizio VO42L question

I have replaced all remaining 7 FET transistors, removed and re-soldered the slave IC, just to be sure that I did it right this time(looked a bit weird at some pins) I have used soldering paste and heat gun and it looks much better then with soldering iron and it's much easier to do too.
The end result is the same black screen, so no change.
Any other ideas?