Olevia 265-t12 - no place to turn but the Internet

[chcbearsfan]

Re: Olevia 265-t12 - no place to turn but the Internet

Thank you retiredcaps. I will test each transformer pair 2-5 and report back the results as plainbill asked. I cannot thank the members of this forum enough. I had been searching for someone just to give me some direction and until I landed here it was looking hopeless.

[chcbearsfan]

Re: Olevia 265-t12 - no place to turn but the Internet

OK I measured each transistor and they all fell withing the acceptable range. Results below. I labeled each with a prefix of R or L depending on the side of the TV it is on, top down starting with 1. There are 2 boards that are identical on each side so there are no distinguishing markings across all inverters.

R1 = .598
R2 = .598
R3 = .599
R4 = .598
R5 = .597
R6 = .598
R7 = .598
R8 = .598
R9 = .598
R10= .600
R11= .597
R12= .596
R13= .600
R14= .600
R15= .598
R16= .598
R17= .597
R18= .598

L1 = .600
L2 = .597
L3 = .597
L4 = .597
L5 = .602
L6 = .600
L7 = .597
L8 = .600
L9 = .597
L10= .597
L11= .597
L12= .598
L13= .599
L14= .599
L15= .598
L16= .598
L17= .599
L18= .600

Let me know what I need to do now or if you need any clarification with the numbers

[retiredcaps]

Re: Olevia 265-t12 - no place to turn but the Internet

1) All those ohms readings look correct which suggest the inverter transformers are likely okay. There still could be something wrong with a component or components on the inverter board.

2) I'm not sure how to test the individual ccfls on a TV this big?

3) BTW, on ebay.com, all 4 inverter boards are available for a total of $165. See

http://www.ebay.com/sch/paylesscompo....c0.m270.l1313

4) I'm not saying it is an inverter board problem because we have no proof yet, but at least there is an option to get replacement boards. I would wait until all options are exhausted before spending any money. We definitely want to rule out a bad ccfl before spending the money.

5) If it turns out that even one Rubycon ZLH cap is bad, it could affect the entire backlight coming on. A replacement from digikey would be Panasonic FC 390uF 35V (71 cents each). If your LCD TV runs really hot, it is possible that the Rubycon ZLH are dried out?

http://search.digikey.com/us/en/prod...1237-ND/356140

6) You would need an ESR tester to measure the ESR and a multimeter with a capacitance function to read uF. Since this equipment costs money, ordering 8 caps (assuming 4 boards x 2 caps) would only cost you $5.68 + around $2.75 USD shipping or $8.43 to rule out the caps as the culprit.

7) Even good quality caps are prone to heat. So if you watch a lot of TV and have your TV pushed up against a wall with no air circulation, it might be worth a try? Panasonic and Rubycon are probably the 2 top names in capacitors.

8) Wait for others to chime in with their analysis and opinions.

[PlainBill]

Re: Olevia 265-t12 - no place to turn but the Internet

I agree with retiredcaps; the transformers look good. The variation was less than 1%.

At this point things get difficult. The choices are replacing a few caps from a manufacturer with a reputation for high reliability (Rubycon, on the inverter); replacing more caps that appear to be good (unknown brand on the 24V output of the power supply); or letting the inverter run with essentially no load.

Let's take the safe approach. Wow, I just took a look at the first picture. Dual power supplies??? What are the brand and series of the caps near the 24V output of the power supply?

Whoops!!! A few brain cells just kicked in - unusual for this time of the morning.
Let's cover ALL the bases. First, another set of pictures; the first one showing the complete set of inverters. The next showing the power input area (the area around the connector with the red and black wires) of each board. All fuses should be checked; the only picture showing a power connection shows three fuses. A single open fuse could cause 'two seconds to black'.

Next, a picture of the output connectors on each power supply; I'm hoping to see some indication of output voltages.

And as I've already mentioned, what are the brand and series of caps in the output area (lower left corner) of the power supplies?

PlainBill

[chcbearsfan]

Re: Olevia 265-t12 - no place to turn but the Internet

3) BTW, on ebay.com, all 4 inverter boards are available for a total of $165. See

http://www.ebay.com/sch/paylesscompo....c0.m270.l1313

Actually I have already worked with Payless and they were rock solid. Basically in my method of troubleshooting I disconnected the power to one inverter board at a time and booted the LCD and replicated the issue until I was down to the master. When I disconnected the small white plug with 5 wires in the bottom on the picture the TV would no longer appear to fault. Because the backlights wouldnt come on I used audible signal to make that judgement. I bought that board from them for $45 and swapped it in but ended with the same result.

So unless the master board has some common component problem it is likely a-ok.

I will get the pics of for you shortly plainbill....

[chcbearsfan]

Re: Olevia 265-t12 - no place to turn but the Internet

I agree with retiredcaps; the transformers look good. The variation was less than 1%.

At this point things get difficult. The choices are replacing a few caps from a manufacturer with a reputation for high reliability (Rubycon, on the inverter); replacing more caps that appear to be good (unknown brand on the 24V output of the power supply); or letting the inverter run with essentially no load.

Let's take the safe approach. Wow, I just took a look at the first picture. Dual power supplies??? What are the brand and series of the caps near the 24V output of the power supply?

Whoops!!! A few brain cells just kicked in - unusual for this time of the morning.
Let's cover ALL the bases. First, another set of pictures; the first one showing the complete set of inverters. The next showing the power input area (the area around the connector with the red and black wires) of each board. All fuses should be checked; the only picture showing a power connection shows three fuses. A single open fuse could cause 'two seconds to black'.

Next, a picture of the output connectors on each power supply; I'm hoping to see some indication of output voltages.

And as I've already mentioned, what are the brand and series of caps in the output area (lower left corner) of the power supplies?

PlainBill

Hopefully this covers everything.

As for the fuses. I think each inverter board has 3 picofuses (sp?) from my research and on the power supplies I see what appears to be a fuse in the top right. Is that what you want me to test and what setting on the DMM should it be?

Let me know if you need cleared or different pictures. The inverterboards with red/white power to the panel is on the right side and the blue white is on the left. The left has the master inverter board centered and the right has the slave centered.

Edit - Unable to tell the mfg for the caps on the power supplies. They all appear to be the same brown ones. I took a closeup so hopefully you could tell from that

[tom66]

Re: Olevia 265-t12 - no place to turn but the Internet

One thing that could cause this problem is one of the inverter boards failing, but the others still functioning. This TV appears to use 6(!!) inverter boards.

There's a simple test to determine which is faulty. Unplug all but one of the inverter boards (from the power supply - not the bulbs) while TV is off. Turn TV on. Do you get a picture for those few seconds? If so, unplug that board, and plug in the next one. Repeat this until all boards have been tested. The board which does not give a picture is probably faulty.

Another thing - when turned on and working (with all inverters connected) - do you notice any non-uniformity in the brightness of the picture? For example is one part of the screen much dimmer than the others?

[chcbearsfan]

Re: Olevia 265-t12 - no place to turn but the Internet

OK, just taking a stab I tested the fuses successfully I think. I set the DMM to 200, 2K and 20K would go from 1. to .00 or .000.

The slave assembly appears to have 2 fuses on each inverter board. I tested each and received the output of .04 across all 6. The Master inverter assembly, each board has 3 fuses and I tested each and received .05 across all 9.

Keeping the same setting on the DMM I tested the power supply fuses and received a reading of .05 against each one.

[chcbearsfan]

Re: Olevia 265-t12 - no place to turn but the Internet

One thing that could cause this problem is one of the inverter boards failing, but the others still functioning. This TV appears to use 6(!!) inverter boards.

There's a simple test to determine which is faulty. Unplug all but one of the inverter boards (from the power supply - not the bulbs) while TV is off. Turn TV on. Do you get a picture for those few seconds? If so, unplug that board, and plug in the next one. Repeat this until all boards have been tested. The board which does not give a picture is probably faulty.

Another thing - when turned on and working (with all inverters connected) - do you notice any non-uniformity in the brightness of the picture? For example is one part of the screen much dimmer than the others?

Thats the first thing I gave a go. Unless I did something wrong I was able to get 2 seconds to black on each inverter. I wasnt able to isolate one at a time because the master has the control (i assume) because without that nothing worked. But each would light a portion of the panel. On the left the slave controls those connected as without it the entire side wouldnt light.

But yes you are correct. They use 6 inverter boards. Is there a way to safely gauge if the psu are delivering the right voltage to the boards or if there is some overvoltage protection that is kicking in that shuts the display down?

It would appear the backlights are good as they fire and the splash looks OK, we are narrowing in on the inverters appearing to be OK, so that would be my next guess. At least not knowing how to work on LCD's before this it seems logical to the novice mind

[tom66]

Re: Olevia 265-t12 - no place to turn but the Internet

Thats the first thing I gave a go. Unless I did something wrong I was able to get 2 seconds to black on each inverter. I wasnt able to isolate one at a time because the master has the control (i assume) because without that nothing worked. But each would light a portion of the panel. On the left the slave controls those connected as without it the entire side wouldnt light.

But yes you are correct. They use 6 inverter boards. Is there a way to safely gauge if the psu are delivering the right voltage to the boards or if there is some overvoltage protection that is kicking in that shuts the display down?

It would appear the backlights are good as they fire and the splash looks OK, we are narrowing in on the inverters appearing to be OK, so that would be my next guess. At least not knowing how to work on LCD's before this it seems logical to the novice mind

Some backlights can start, but then fail. Think of a fluorescent tube for a kitchen or office. When nearly failed, they are able to start, but quickly extinguish themselves, and they repeat this pattern over and over, leading to a flickering light. But, a CCFL inverter will shut down as soon as a fault is detected, so you'll only get one flash.

Which one did you assume was the master? It's usually marked, and has a connection to the other boards. It may have instead been the faulty one.

I would suggest unplugging all but one of the bulbs, seeing if it would light, and then trying that for all bulbs, but I fear that it wouldn't be conclusive as one bulb of the set can start but not continue operating. Someone somewhere suggested a 100kohm 3W high voltage resistor could be used to create a simulated CCFL, but I'm not sure how well that would work.

To test the power supply outputs... That's easy, but I'll need a picture of the connector on the inverter board to tell you where to probe.

[retiredcaps]

Re: Olevia 265-t12 - no place to turn but the Internet

OK, just taking a stab I tested the fuses successfully I think. I set the DMM to 200, 2K and 20K would go from 1. to .00 or .000.
.

For future testing, a good fuse should measure less than 1.0 ohms. So use the 200 ohm scale to get the most resolution/accuracy.

[retiredcaps]

Re: Olevia 265-t12 - no place to turn but the Internet

Edit - Unable to tell the mfg for the caps on the power supplies. They all appear to be the same brown ones.

The "K" vent are Rubycons.

The brown ones with "Mercedes Benz" vent have a crown symbol on the sleeve are made by United Chemi-Con (UCC). Specifically, they are KZE series. The KZG series are definitely problematic as per (they are mainly used on computer motherboards, but I have seen bad KZG on lcd monitors as well)

https://www.badcaps.net/forum/showthread.php?t=2280

The ones with the "+" vent look like they are Nichicon caps.

All 3 are reputable cap manufacturers.

[retiredcaps]

Re: Olevia 265-t12 - no place to turn but the Internet

Is there a way to safely gauge if the psu are delivering the right voltage to the boards or if there is some overvoltage protection that is kicking in that shuts the display down?

On the 6 inverter boards, it looks like all the red colored wires are 24V DC (and possibly 12V DC) according to the power board legend.

So you can either measure for 24V DC on the inverter board connector or power board connector. This voltage should be steady and not fluctuating. You want to measure all the red wires on all boards.

This TV design/layout makes reminds me of wanting to buy a king sized bed by purchasing 2 twins and pushing them together.

[chcbearsfan]

Re: Olevia 265-t12 - no place to turn but the Internet

On the 6 inverter boards, it looks like all the red colored wires are 24V DC (and possibly 12V DC) according to the power board legend.

So you can either measure for 24V DC on the inverter board connector or power board connector. This voltage should be steady and not fluctuating. You want to measure all the red wires on all boards.

This TV design/layout makes reminds me of wanting to buy a king sized bed by purchasing 2 twins and pushing them together.

Interesting note on the design. I am not surprised since it is Olevia as that is more of a value brand.

This might be a stupid question but to measure them what setting do I use on the DMM and which probes go where? The red and the black probe each on a red wire? What do I need to make sure to avoid in order to be safe? I have not worked on an LCD panel before so I am not sure which points carry dangerous voltage. I am mostly just really cautious with the thing but when there is power I havent done anything except power down plug in or unplug the inverters and power up.

[tom66]

Re: Olevia 265-t12 - no place to turn but the Internet

Interesting note on the design. I am not surprised since it is Olevia as that is more of a value brand.

This might be a stupid question but to measure them what setting do I use on the DMM and which probes go where? The red and the black probe each on a red wire? What do I need to make sure to avoid in order to be safe? I have not worked on an LCD panel before so I am not sure which points carry dangerous voltage. I am mostly just really cautious with the thing but when there is power I havent done anything except power down plug in or unplug the inverters and power up.

Basically, don't touch the power supply's heatsinks, and you'll be fine. Even if you touch one, you will only feel a kind of metal pricking/tingling sensation, because the heatsinks are live, attached to the mains phases in some way.

On the connector on the inverter, you will see some red and black wires. If you're clever, you can gently wedge the probes into the connector, where the wires meet. You want to connect red to red and black to black. Do this while off. Turn on your multimeter and select the 200V range. Then turn the TV on the normal way. Report the voltage while the inverters function and when they go out.

Have we determined if any part of the screen looks a bit dimmer when displaying the logo? I just did an experiment with a small 32" LCD. When a CCFL is unplugged, the TV works for about 2 seconds. During those 2 seconds if you look carefully you *can* notice a portion of the screen which is dimmer than the rest corresponding to the unplugged tube. You will need to look carefully.

Perhaps it may help to plug in an input to the TV which is full white, like from a PC VGA using MS paint or equivalent. Then, disconnect the connector from the inverter to the main board. Connect this back in; look carefully for a darker spot before the screen goes dark.

[retiredcaps]

Re: Olevia 265-t12 - no place to turn but the Internet

This might be a stupid question but to measure them what setting do I use on the DMM and which probes go where? The red and the black probe each on a red wire?

Black goes into COM on your multimeter. Red goes into Volts on the multimeter. Turn your dial to 200V DC. Don't worry, you are not measuring 200V DC, but since we are looking for 24V DC, we cannot set the dial to 20V DC otherwise we get a "1" on the left hand side which indicates out of range.

Black probe goes to a ground screw closest to your measuring point or a black wire connector. This is your ground.

Red probe goes to what you are trying to measure. In this case, it is the red wire connector. It looks like there are 5 red wires per connector so you should get 5 readings. Not all the red wires may carry 24V DC??? Some may read 0V DC, but I'm assuming ALL the inverter boards should read identical on a "per pin basis". It is best to record all the readings on a sheet of paper for comparison and then you can post the results.

Have a steady hand and good light to take these measurements. A slip of the probe can short something out quite easily.

edit: Again, while I was writing this response, tom66 beat me to it. We are both saying the same thing. His method of wedging the probes into the connector while the TV is off is an excellent one.

[chcbearsfan]

Re: Olevia 265-t12 - no place to turn but the Internet

Excellent information, thank you very much. I will test the voltage on each and report the findings. Is this the right approach? Should there be some other troubleshooting I should do or do you think looking at power at this point is right?

Thanks again!

[tom66]

Re: Olevia 265-t12 - no place to turn but the Internet

Excellent information, thank you very much. I will test the voltage on each and report the findings. Is this the right approach? Should there be some other troubleshooting I should do or do you think looking at power at this point is right?

Thanks again!

You should only need to test one pair of red and black wires (any pair) for each inverter.

[chcbearsfan]

Re: Olevia 265-t12 - no place to turn but the Internet

OK so I tested the power connectors connecting to the inverter boards. There are some inconsistencies but I dont know if it means anything. I will label the inverters for this purpose 1-6 going from the bottom left clockwise through the bottom right. All red wires measure the same for the respective inverters.

Inverter 1 - 54.7
Inverter 2 - 54.7
Inverter 3 - 54.7
Inverter 4 - 53.9
Inverter 5 - 53.9
Inverter 6 - 53.8

I set the DMM to the setting of 200 on the dial where there is a V~. The power stayed through the 2 seconds to black so the inverter appears to be the one that triggers the fault.

I tried to measure the actual voltage output to the bulbs but I couldnt find the right setting to measure as when the power turned on the reading went to 1. then black back to 0.

Hope some of this makes sense to any of you. Please help me to the next step

[retiredcaps]

Re: Olevia 265-t12 - no place to turn but the Internet

I set the DMM to the setting of 200 on the dial where there is a V~.

V~ is AC. We want to measure DC.