Element elcfw328 broken CCFL and 2 seconds to black?

[tucocaps]

Hello Everyone,

This is a question about this set, but also a general question.

This set has a VERY smashed panel, and as I've seen before, when I power up, the backlight will flash white light for a moment, and then the screen goes dark. The power led goes from red to BLUE, and the unit appears to stay on fine. All other boards on the unit visually look OK, but I am unable to get any sound from the set.

What I'm wondering is would the mainboard be shutting something down if one of the CCFL is causing a problem on the inverter/power board? If so, is there any way to "trick" the set into powering up at least the mainboard, audio, etc. to test that? I do know that budm's CCFL lamp rig could be used to test the inverter, but I don't currently have that, and wondering if it's needed for a small set like this. There are only two plugs, so I guess two backlights on the 32" set.

Thanks!

[CapLeaker]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

Look with an oscilloscope at the lvds signal and press the menu button. You should see a difference on the o'scope screen each time you press the menu button.

[tucocaps]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

thanks capleaker, but i don't have an oscilloscope, nor do I know how to use one. I'm also wondering if the scope is a good way to test mainboard functionality. I've been doing quite well with the "sound and remote" method so far.

I really just would like to know if the LCD's are in fact set to shutdown in some way when there is a short CFL. Also, what if that CFL is unplugged? Should that allow set to power on normally if the inverter is OK?

[CapLeaker]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

The inverter shuts down by itself if it senses a defect, the rest should keep on running as long as the power supply is turned on. If you want, you can disconnect the inverter board from the power supply. If you turn the power supply on the main board should power up together with the Tcon and the lcd. In your case the lcd is screwed, so you got not much going for you.
With the o'scope on the lvds, it tells me if the board booted up and if the menu is working or not. It will not tell me anything about the inputs, unless I am lucky to find the correct input and put a signal into it. It is not like I see a mini screen on the o'scope, it would be a signal of a part of the screen a low voltage differential signal.

[tucocaps]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

Thanks Capsleaker. I sort of understand what you are saying, but this set appears to have a power supply and inverter combined into one board I think?

Also, the way I check the mainboards is to program a universal remote, and then try to use the most direct button to change to an input such as HDMI1. I'm usually able to test all the inputs, except for the occasional set like this. I only have an "input next", but I'm pretty sure it's not working for whatever reason anyway. The mainboard may just be bad, so now I don't know if the inverter psu is bad too.

Can a panel off of any other set be used to test inverters or inverter/psu combo boards? I was thinking about extending the wires, and then just making the connections to the inverter board on the set with the broken CFL's.

[tucocaps]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

This is the power supply/inverter board.

[tucocaps]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

and this is the mainboard. I wonder if this is the culprit behind the no sound, but steady power? I still don't know how to tell if a cap is "bulging", but if you look at the second green/gold cap from the left, the top looks bulged in the four "pie slice" area that is scored on the top. Looking from the side, I can't see a raise in the top of the capacitor. Could it be a bad cap ?

[CapLeaker]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

It really doesn't matter as long as the power supply stays on.
Sometimes using a universal remote to test TV's is not a good idea either. I just came across another TV the other day, where I couldn't get the universal remote to work, on the TV I just fixed. Found out that the code I put in was correct cording to the manufacturer, but the IR command set they used with that particular TV was not. I could see the IR on my scope from the IR receiver, so I knew the sensor was working and it had to be something with the remote, as I was using the buttons on the TV just fine.
Bad caps are hard to detect sometimes unless you have proper equipment. Generally every cap that has something visibly wrong, I'd change out. You will come across some they look fine, but don't measure good at all.
Testing the power supply or a power supply inverter board is easy. Look and smell for the obvious, run over all fuses, mosfets, diodes and check for shorts. Jumper force the power supply on and plug it in (check out the lamp in series with the AC line trick). Measure the outputs. Done.

In your case, an old 720p TV that is smashed and been outside for a while, I'd be taken the PS out for spare parts, maybe a CCFL and the rest is garbage. Id be trying much harder if it is a better quality and newer TV set. But I wouldn't invest too much time in these el cheapo sets. Those el cheapo sets are plentiful to come, some with easy fixes, some don't need any fixes (yes, I lucked out like that before) and some sets that were just for some spare parts.

[selldoor]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

Just how smashed it the panel?? You say it flashes bright then goes out?
That suggests that at least one bulb is working.

You also say there are 2 sockets/lamps but there look to be 3? is one just not used - really need a picture of YOUR power supply. (Front and Back)

First try this - note - the lamps will not stay on during this test.

Switch off unplug all but one lamp connector switch on does it flash?
Switch off unplug that lamp and plug in another one (If it will reach preferably in the same socket as the first) Switch on - does it flash?
Switch off if there are three unplug the second then plug in the third.
This will tell you which/how many bulbs are totally dead.

Next when you have a known bulb that flashes test that one in each socket.
(Switch off between plugging/unplugging) This might indicate if there are major problems with the inverter transformers.

If you have a spare panel with similar size bulbs you can also try those in the sockets - if lucky you may get 3 that stay on.
Alternative is to mak up one or two budm test bulbs from a cfl

[tucocaps]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

selldoor: thanks for the reply! I did a test like that with the backlight late last night, but I think I'm going to try it again. Will post a picture of my PSU. It seems the power led could turn "on" blue , but the set may still not operate properly due to a problem with the inverter psu board. I think I'm going to check the voltage at all the psu output pins, and if there is a problem maybe try to troubleshoot.

capsleaker: I get your point about the cheapo sets, but I'm getting kind of obsessed with fixing these because I'm trying to learn from them without having much cost involved. If it drives me crazy and I throw it out, not much loss other than my hair and health

[CapLeaker]

Re: Element elcfw328 broken CCFL and 2 seconds to black?

O.k. on this being a learning curve set. So fire it up and check the voltages on the ribbon from the power supply to the main board. On the pic bottom right. There is the pin out printed on the board too. All voltages there, then it should be good. Power supply done. You can try if there is a difference while the lights flash on, or disconnect them all together, but I doubt that.
For the next step (checking the main board) I use an oscilloscope, not sure what others use, when the screen is damaged like that, but that's what I do.
Remember that only the 5v vsb is there all the time, all other voltage rails are only there when all of the power supply is turned on.