Olevia 242FHD-T11 no picture, but has sound

[rayrod81]

Re: Olevia 242FHD-T11 no picture, but has sound

Every process on this TV is controlled by the main board. The way it is set up the power supply sends voltages to the main board, the main board sends the voltage to the T-con and the T-con then sends the signal to the inverters to turn on the backlights. The backlights on these TVs will not come on unless the T-con receives the signal from the main board to turn on. It is possible that the T-con could be holding everything back but the only way to know would be to replace it with a working one. On the TV I fixed the problem was very similar, if not the same, to your first set of circumstances. I checked all voltages on the power supply and they were fine. The inverters checked fine so that left me with the main board as the culprit. I checked my board by heating it with a heat gun for a few seconds and then trying to power it on. It powered on and everything worked great. At this point, I thought is was a capacitor problem and recapped the board but still had the same problem. Rather than chase the problem I decided to buy a new main board and the TV has been working fine since. Based on the info I found this seemed to be a very common problem on Olevia TVs.

[jeepitbull]

Re: Olevia 242FHD-T11 no picture, but has sound

We tried the darkroom test a few times now and know flash our light what so ever . I would try the old power supply but I don't think it will even turn the TV on any more that's the reason it was replaced . I have also replaced the TV with two new power supplies cause I thought that was the problem the first time I put the new power supply in , so like I said I replaced it with a new power supply and got same results and all the voltages to the inverters read good . So now I am not sure where to check next for the problem , any other suggestions you our anybody else may have would be greatly appreciated. Again Thank you for your Time .

[jeepitbull]

Re: Olevia 242FHD-T11 no picture, but has sound

So you think it could be the main board or Tconn board ? I take it there is know way to check either one to see if they are the problem or not with out replacing them?

[PlainBill]

Re: Olevia 242FHD-T11 no picture, but has sound

So you think it could be the main board or Tconn board ? I take it there is know way to check either one to see if they are the problem or not with out replacing them?

Basic troubleshooting theory indicates that you take a logical approach. First you determine the nature of the problem, then you determine what failed. Next you determine the cause of a failure, and repair that. Further, theory states that if you replace part 'A' and a new problem occurs, either the new part 'A' was defective, or you made some other change when replacing part 'A'.

Let's work our way through this problem. I already have an idea, let me grandstand for a few minutes.

By the original symptoms AND your experience, replacing the power supply was reasonable. The actual problem likely was bad capacitors. Further, the initial problem has been resolved - the blue light comes on, and when the power button is pressed, the blue light goes off, and you get sound.

Conclusion: The power supply is providing the correct power to the main board; the main board is working properly, and since you can see a (dim) picture, the tcon is good. That leads to a further conclusion - the problem is in the backlight system.

The backlight system consists of the inverters, the CCFLs, the section of the power supply that provides inverter power, and the portion of the main board that controls the inverter.

1. You have tested and found the power to the master (slave?) inverter and the control signals are both good on at least one of the inverters.

2. Neither inverter shows any of the usual signs of failure - fuses are good, no transistors are shorted.

3. You don't get even a brief flash from the backlights.

What haven't you checked? And what mistakes have others (including myself) made that would explain the problems?

One thing that came to mind is the thin ribbon cables that link the master and slave inverters. Are those properly seated? That is the only thing I can think of that might be the cause. IF one was disconnected, it is tricky to get them back in correctly.

Beyond that, are all of the connectors from the main board to the power supply properly seated? Are all of the connections from the power supply to the inverters properly seated? Did a screw get put into the wrong hole and damage something?

If none of these items help, please provide a picture of the back of the set. Maybe someone can spot something.

PlainBill

[WayneI]

Re: Olevia 242FHD-T11 no picture, but has sound

Did you ever get the Olevia working again? I have a selfish reason for asking in that I am experiencing a similar (but not quite identical) issue with my 242T11.

It began when the TV wouldn't turn on (no blue light -- nothing). I checked and the power supply fuse was blown, I replaced (with a glass slo blow -- all I could find) and it immediately blew again. I disconnected all cables from power supply, put in a fresh fuse and it immediately blew again. I then replaced the power supply and now have sound but no picture.

I can change the channels with the remote and get sound. I see no indication of a backlite or of even a dim picture on the screen. I have 24v going to the inverters and have checked the fuses and transistors as described above and got a similar 8.45K reading on the transistors. The blue wire (ON/OFF ?) on both inverters has 4.2v coming up several seconds after I turn the set on (about the time it usually took for a picture to appear) and the yellow (brightness ?) is slightly over 2v.

If anyone has any thoughts or ideas they would be appreciated.

[retiredcaps]

Re: Olevia 242FHD-T11 no picture, but has sound

I checked and the power supply fuse was blown, I replaced (with a glass slo blow -- all I could find) and it immediately blew again. I disconnected all cables from power supply, put in a fresh fuse and it immediately blew again. I then replaced the power supply and now have sound but no picture.

On the original board, it sounds like the bridge rectifier might be shorted which would cause your fuse to blow right away.

[WayneI]

Re: Olevia 242FHD-T11 no picture, but has sound

Thanks --- Since I went ahead and got a new power supply, probably won't try to fix that one. Any thoughts on any damage that could cause to other boards when it went out?

I visually checked the original power supply (before I ordered a new one) and couldn't see any indication of burning or any "bulging" caps on the board. I figured something must be shorted on it or it wouldn't blow the fuse immediately when I plugged it in with no load connected.

I'm also a bit concerned with the 5 volt supply on the new one --- it was only suppling 4.2 volts to the inverter (seems like enough if it is just running a switch, but jeepitbull was getting 4.95 v).

[cadiman]

Re: Olevia 242FHD-T11 no picture, but has sound

With a bad slave inverter you will still get two seconds to black.

If you unplug and remove the slave inverter you will still get the two seconds to black as long as the master is good.

[WayneI]

Re: Olevia 242FHD-T11 no picture, but has sound

Thanks for the info. I don't see any indication of a screenglow or a picture -- Not a glow for a couple of seconds and then dead --- nothing. So I'm not sure if something is killing the backlite AND the picture or what is going on.

[cashkennedy]

Re: Olevia 242FHD-T11 no picture, but has sound

The original board probably had bad FET's, theres another thread on this forum where i recently fixed the power supply in 1 of these, and 2 other people had exactly the same bad FET's , which caused instant fuse blows.

Anyway since he bought a new used PSU its not really an issue for him anymore, Im confused though whether his tv shuts off after a short time, or if it stays running with sound, but no picture for a long time. If its shuts off its probably backlight, if it doesnt shut off it might be other things / disconected cable from when he replaced the psu, who knows.

Have you tried using a flash light at and angle or from behind to see if possibly your getting the picture, just not the backlight to shine light through / illuminate the picture.

[WayneI]

Re: Olevia 242FHD-T11 no picture, but has sound

The TV will remain on with sound playing (The longest I left it on was probably 10-15 minutes -- but there was no indication it would shut off by itself -- I always shut it off with the remote or switch). I did take a flashlight and shine at an angle on the screen, but could see no indication of a picture.

[WayneI]

Re: Olevia 242FHD-T11 no picture, but has sound

I could try to get my old power supply going if there is a chance that there is a problem with my new one (I'm a bit concerned about the 4.2v). But since I already installed a new one, if that isn't likely the problem, I'ld rather try to figure out what else might be wrong.

Thanks for all your help.

[cashkennedy]

Re: Olevia 242FHD-T11 no picture, but has sound

What about the other voltages, like the red wires (24v,) and the brightness (~ 3v) going to the inverter, and the wires going to the mainboard. Also are you taking DC readings, perhaps your taking AC voltage readings. Are you taking them vs real ground, try taking them to a "ground" wire that is part of the wires running between the inverter and power supply, then try taking the reading to a real ground (like a screw that is grounded on the tv).

Edit: sorry i see above you posted most voltages, but make sure you were taking them on DC, and try both ground options, though it sounds like your somewhat knowledgeable.

[WayneI]

Re: Olevia 242FHD-T11 no picture, but has sound

I'll take somewhat knowledgeable as a complimant --- THANKS!! I did use the screw that had one of the ground wires mounted to as a reference when I took the measurements (on the master side -- there wasn't one on the slave inverter side so I just used the frame) -- and I'm confident I was reading DC. I didn't check the voltages going to the main board ( I did double (actually triple) check that it looked like I had them installed properly). I had to change the cables with the power supply since the replacement Power Supply I bought didn't have the same connectors (which didn't make me comfortable). But the 'distribution' end of the connectors that came with the power supply all fit into the other boards so I "assume" all is well with that.

Thanks again for your help

I'm not sure of the function of the Tconn board (nor do I know which one it is) or of the main board (other than to control all the functions), so I'm not sure which direction to head, or if I should just write of the $60 I spent on the PS and haul the whole thing to the dumpster.

[cashkennedy]

Re: Olevia 242FHD-T11 no picture, but has sound

The fact that the power supply had different connectors would be pretty alarming to me. Was it exactly the same model power supply? Was the seller selling it as compatible with multiple models? They included the new cables with the power supply to make it work?

The main board interprets the inputs / cable to determine what should be on the screen, it also tells and monitors the inverter which lights the backlight, and it sends the final signal for the video to the t-con, the t-con is specific to the panel and know the exact voltages / paths to send the signal through the LCD to turn the pixels on and off. So to produce the image there is the t-con controlling which pixels are open / closed, and the inverter powering the backlight.

If you cant get it to work a repair person might buy it from you for 30-50 dollars, could try craigslist, usually theres people there advertising to buy broken LCD's and plasmas.

[WayneI]

Re: Olevia 242FHD-T11 no picture, but has sound

Thanks for the response.

So it seems to me that if I don't have either a picture or a backilite that would point to either the main board or the power (or a failure of both the inverter and the t-con). Does that logic seem sound?

I ordered the board off e-bay and it was advertised as 'new', the seller had a lot of them (probably 100). The supply looks like it was never used, came with the cables still 'bread-tied' together, all inside a foam sleeve. I guess someone could do that to an old supply but it would seem lie a lot of work. It has the same part number and was advertised as being for the 242-T11 that I have. So I think it's "probably" OK.

I did check my old power supply and I think there is a short on the rectifier (kudo's to retiredcaps) -- The pin marked "+" measures as a short to the nuetral (non-fused) side of the AC supply. I can't imagine that's right. I may try to swap it out if I can find one and put this supply bac in if it fixes it, since I'm still concerned about the 5v supply on yhe new one I got.

[cashkennedy]

Re: Olevia 242FHD-T11 no picture, but has sound

It would be more likely that it's either the mainboard or psu (1 failure), rather then both the t-con and inverter. But by no means is that for sure.

The earlier entries in this thread mentioned the mainboard being usually the culprit in problems with this model, so i would lean towards that part being bad, and not your new power supply. But thats only a guess.

[WayneI]

Re: Olevia 242FHD-T11 no picture, but has sound

I have been thinking about the inverter. If it has power (+24v) and the +5v (4.2v in my case) on the blue wire (presumably the On/Off signal), and some level (2v) on the yellow wire (brightness?), is there any reason the backlights won't come on unless there is a problem with the inverter or light? Is there any other signal it should be getting (presumably from the main board)? Do you think the 4.2v may be too low to "switch it on"?

[cashkennedy]

Re: Olevia 242FHD-T11 no picture, but has sound

Because in most TV's the mainboard decides brightness, and also monitors for when there is a fault in the backlight (so that it can decide to turn off) I believe most use a form of communication that isnt simply monitored by voltage ( some sort of machine binary signal / data signal). Granted your TV is either broken so not shutting off from this fault, or wasnt designed to turn off from a fault.

[WayneI]

Re: Olevia 242FHD-T11 no picture, but has sound

I checked the 5v (blue wire) signal to the inverters with the inverters disconnected and measured 4.9v. With only the slave inverter connected, the voltages remains at 4.9v. When I connect just the master (or both master and slave) the voltage drops to 4.2v. Just wondering if that sounds normal or if there is something loading down the signal on the master inverter?

That still doesn't address my lack of picture -- I'm getting a bad feeling that when the power supply fried on this it may have taken several things with it.