Olevia 342-B11 No signs of power still.

[Robbiebaby]

This is a follow up to the previous thread I had about this TV (Original thread here: https://www.badcaps.net/forum/showthread.php?t=16434. This was a TV that had a power surge and fried some parts on the original PSU. I replaced the PSU on it with (I hope) a good one. I moved up from square 1, but now im stuck on square 2 :-/ The TV shows no signs of any power, no standby light, no anything. I do get power in the following areas though:

The main cap still gets 152.8.

The 5v SB rail (labeled 5v s on the psu) is the only thing that gets a constant voltage. It get 5.04v

On the same connector I also have a brown wire labeled O/F - It gets no voltage no matter if I press the button or not.
There is also a Blue wire, it is labeled B-ON. When I plug in the TV, it reads 0.0, when the power button is pressed, it goes to 3.57v. When pressed again, it goes back to 0.0. Nothing happens to the TV when the power button is pressed though.
Then there is a yellow wire, labeled BR1. This one reads 0.0 initially when plugged in, then when the power button is pressed it jumps to 2.86v and stays at 2.86v after that. It doesn't go down after I press the power again.

[PlainBill]

Re: Olevia 342-B11 No signs of power still.

This is a follow up to the previous thread I had about this TV (Original thread here: https://www.badcaps.net/forum/showthread.php?t=16434. This was a TV that had a power surge and fried some parts on the original PSU. I replaced the PSU on it with (I hope) a good one. I moved up from square 1, but now im stuck on square 2 :-/ The TV shows no signs of any power, no standby light, no anything. I do get power in the following areas though:

The main cap still gets 152.8.

The 5v SB rail (labeled 5v s on the psu) is the only thing that gets a constant voltage. It get 5.04v

On the same connector I also have a brown wire labeled O/F - It gets no voltage no matter if I press the button or not.
There is also a Blue wire, it is labeled B-ON. When I plug in the TV, it reads 0.0, when the power button is pressed, it goes to 3.57v. When pressed again, it goes back to 0.0. Nothing happens to the TV when the power button is pressed though.
Then there is a yellow wire, labeled BR1. This one reads 0.0 initially when plugged in, then when the power button is pressed it jumps to 2.86v and stays at 2.86v after that. It doesn't go down after I press the power again.

BR1 is actually BRI - brightness. B-ON is Backlight ON. O/F is On/Off. Trace that one back to the main board. The processor is turning on everything, but for some reason the O/F line is not going high.

PlainBill

[Robbiebaby]

Re: Olevia 342-B11 No signs of power still.

Ok, I checked the lines, but I dont really know if Im looking for anything specific.
I took and edited the picture of where the cable plugs in, I have both sides.

I dont know if this is what you were asking, but here you go

The O/F (brown) line is connected to some other lines on the connector. I made them orange in the picture (according to continuity)
The blue lines are also connected together.
I wasn't able to really find where the orange lines go on the circuit, they didn't show any obvious signs of connection anywhere in the proximity of the connector. though I did get the occasional split second beep from the continuity meter when checking along the whole board, but that only happened in maybe 3 or 4 places.

The blue is also traced out, that one was much easier and it even goes on further than what I labeled.

[PlainBill]

Re: Olevia 342-B11 No signs of power still.

Ok, I checked the lines, but I dont really know if Im looking for anything specific.
I took and edited the picture of where the cable plugs in, I have both sides.

I dont know if this is what you were asking, but here you go

The O/F (brown) line is connected to some other lines on the connector. I made them orange in the picture (according to continuity)
The blue lines are also connected together.
I wasn't able to really find where the orange lines go on the circuit, they didn't show any obvious signs of connection anywhere in the proximity of the connector. though I did get the occasional split second beep from the continuity meter when checking along the whole board, but that only happened in maybe 3 or 4 places.

The blue is also traced out, that one was much easier and it even goes on further than what I labeled.

The two pins of interest are 5Vs and O/F. Just above the connector are two LDO regulators. The one on the right is U8; I don't see the identifier for the one on the left. The pins are numbered 1, 2, 3 from left to right. What are the voltages on each of those ICs? Those regulators provide the voltages for the standby processor, which turns on the main power supply. This may be a multilayer board, If so it will be a big problem tracing the O/F signal.

PlainBill

[Robbiebaby]

Re: Olevia 342-B11 No signs of power still.

The pins in U8 measure:
1. 1.265v
2. 2.519v
3. 5.06v
The other one (U9) measures
1. 2.085v
2. 3.333v
3. 5.06v

Would you say this is a problem with the main board? or should I send the replacement PSU back? Or...We dont know yet? :-)

[PlainBill]

Re: Olevia 342-B11 No signs of power still.

The pins in U8 measure:
1. 1.265v
2. 2.519v
3. 5.06v
The other one (U9) measures
1. 2.085v
2. 3.333v
3. 5.06v

Would you say this is a problem with the main board? or should I send the replacement PSU back? Or...We dont know yet? :-)

Those voltages indicate the regulators are working properly.

I am ALMOST certain the power supply is working properly. One simple test is to insert a 3.3K resistor between 5Vs and O/F. If the main power supply now comes up you are sure that nothing on the supply is holding O/F low. In that case, the power supply is certainly good.

If you go one step further and try this with the power supply connected to the main board and the TV works, you can be sure you have a hardware problem of some sort between the output of the controller on the main board and the connector, and it may be worthwhile pursuing.

PlainBill

[Robbiebaby]

Re: Olevia 342-B11 No signs of power still.

I have a 1/4w 3.3k ohm resistor, I jumped 5Vs and O/F on the PSu connector, but nothing happened. But the thing is, there was no voltage going to the O/f through the resistor from 5Vs. Maybe im using the wrong kind of resistor?

[Robbiebaby]

Re: Olevia 342-B11 No signs of power still.

Oops, I forgot to mention what I did in the earlier post.

Anyways, here is the rundown on what happens with the 3.3k resistor I have. when I jump the PSU without the main board connected the PSU doesn't turn on, but I get 2.05V going to O/F through the resistor (jumped from 5Vs). I get no voltages on the other rails.
When I have the resistor jumped with 5Vs and O/F with the main board connected I still get nothing, but I get 0v going to the O/F through the resistor.

I think im doing something wrong....

[PlainBill]

Re: Olevia 342-B11 No signs of power still.

Oops, I forgot to mention what I did in the earlier post.

Anyways, here is the rundown on what happens with the 3.3k resistor I have. when I jump the PSU without the main board connected the PSU doesn't turn on, but I get 2.05V going to O/F through the resistor (jumped from 5Vs). I get no voltages on the other rails.
When I have the resistor jumped with 5Vs and O/F with the main board connected I still get nothing, but I get 0v going to the O/F through the resistor.

I think im doing something wrong....

Or you were following directions that don't apply to this TV.... 2.05 volts is too low to reliably turn on the main supply; try a 2.2 K resistor.

Also, with the power supply disconnected, on the main board, measure the resistance from the O/F pin to any ground pin.

PlainBill

[Robbiebaby]

Re: Olevia 342-B11 No signs of power still.

Well I tried a 2.2k resistor and this time I get 2.43v going to O/F and still nothing

Also I measured the resistance to the pins, The O/F is pretty much around 2-3M ohm to all the ground pins except for 2/ One has 19M ohm, and another has no resistance at all, its the one that is orange in the attached picture from earlier.

[Robbiebaby]

Re: Olevia 342-B11 No signs of power still.

What is the target voltage that i'm supposed to be getting into the O/F anyways?

[PlainBill]

Re: Olevia 342-B11 No signs of power still.

What is the target voltage that i'm supposed to be getting into the O/F anyways?

Usually it's over 3 volts, I've seen 3.2 or 3.3 volts on that line.

PlainBill

[Robbiebaby]

Re: Olevia 342-B11 No signs of power still.

Well, I found a 1k resistor, I got the voltage to 3.3v. But still nothing......Maybe this used PSU is defective :-| Ugh

[PlainBill]

Re: Olevia 342-B11 No signs of power still.

Well, I found a 1k resistor, I got the voltage to 3.3v. But still nothing......Maybe this used PSU is defective :-| Ugh

It's possible.

PlainBill