Beko 30inch blank screen after 2 sec.

[HK-Steve]

Hello Everyone,
I have spent some time today trying to get a Beko 30inch LCD tv working.
I do not have a specific model number, as it has it's case removed.
On the Firmware Chip was - LT30FLF ver 2.9 2005

Screen goes blank after 2 seconds, sound is good.

The Inverter board is a Model V144-001.
Main Board is Model V2327B/D 111-A48F.
The LCD panel is V296W1-L11.

I went through the Great post on troubleshooting, this is what I found,

1- Bad capacitors,
I replaced them all on the Inverter board, all originals checked good when I removed them, I checked the power supply, it is an outboard power supply, not inside the tv, all checked as good using my capacitance meter.

2- Shorted transistors,
not sure where to check yet, help please if you can.

3- open Fuses,
checked every fuse I could find, all are good.

4- Bad transformers,
checked with multimeter, 940 to 960ohms.

5- Bad CCFL,
unplugged 2 at a time, turned tv ON, still same black screen after 2 seconds.

6- Bad Diodes,
Will test further, but would appreciate help here also.

7- Bad/Cold/poor solder joints,
Checked every board with magna fine glass, all solder joints were good, plus unplugged and replugged all socketed cables.

8- I measured the various voltages, found all normal from what I can tell.


Now off to find some schematics

Much Appreciate any comment or Suggestions.

Cheers
Steve

[Glitcher]

Re: Beko 30inch blank screen after 2 sec.

So what happens to the inverter voltage input when the bkaclights shut off?

[HK-Steve]

Re: Beko 30inch blank screen after 2 sec.

I was about to check the voltages,
Pulled the Inverter board out, as I wanted to know the pinout for the voltages, took a picture,

Then put the Inverter board back in, (this is the 3rd time out and back in)
Fired up the TV, and it works!!!!!!!

Cycled the TV ON/OFF 5 times, it runs,
I will run it tonight and tomorrow, seems a bit strange.

As for the running voltages, the 24v line is 23.7volts
Vsel = 4.1
VEPWM = 5.0
VIPWM = 0.0
On/Off = 5.0


Cheers

[tom66]

Re: Beko 30inch blank screen after 2 sec.

Probably a cold solder joint -- would be surprised if it lasted.

[JonathanAnon]

Re: Beko 30inch blank screen after 2 sec.

Yeah, I'd agree with Tom, sounds like a cold joint, maybe on one of the connector points.. Or maybe a dodgy wire on the connector from the PSU to the inverter board... Maybe reflow all the solder points around the connector, and any bad looking solder joints.. ?

[multimeter]

Re: Beko 30inch blank screen after 2 sec.

5- Bad CCFL,
unplugged 2 at a time, turned tv ON, still same black screen after 2 seconds.


you need to unplug 2 at a time and plug 2 SPARES in there place to test ccfl's
or the shutdown circuit will sense they are missing and still give you 2 secs to black

[HK-Steve]

Re: Beko 30inch blank screen after 2 sec.

Thanks Guy's,
Appreciate all the suggestions.

First, I will reflow the solder for the connections, They all looks good, but no harm to try.

I have no spare CCFL's to plug in, but as it started to work for 30 mins, that would suggest the CCFL's are ok, yes??


Also, I am sure I saw somewhere here, about a service menu, but can not find the thread now.


Love this forum already, great stuff everyone.

Cheers

[multimeter]

Re: Beko 30inch blank screen after 2 sec.

Thanks Guy's,
Appreciate all the suggestions.

First, I will reflow the solder for the connections, They all looks good, but no harm to try.

I have no spare CCFL's to plug in, but as it started to work for 30 mins, that would suggest the CCFL's are ok, yes??


Also, I am sure I saw somewhere here, about a service menu, but can not find the thread now.


Love this forum already, great stuff everyone.

Cheers

yes it would/could indicate that the ccfl's are ok ,if on after 30mins,but it could be a dodgy intermittant ccfl wire going to the end of the tube, a spare ccfl would rule this out,you only want to tear down the panel if absolutley needed,sounds like it could be a dry joint somewhere.

you could try powering on the tv in the dark and flex the boards with a plastic rod or trimmer tool and look for a little spark,a blast of freeze spray on the offending joint will make it work ,only temporary though.

[HK-Steve]

Re: Beko 30inch blank screen after 2 sec.

Thankyou everyone,
I have worked out it is the inverter board, I move it up just a little on one corner, and out goes the backlight.

I have soldered as many points as I can, but have no way to reflow the board myself.
Does someone have the equipment, and time??

Or a board they are willing to sell??



Much Appreciated.

Cheers
Steve

[tom66]

Re: Beko 30inch blank screen after 2 sec.

There is also the chance it is a loose bulb connector in the LCD panel.

[HK-Steve]

Re: Beko 30inch blank screen after 2 sec.

I do not think so, as the corner was lifted about 2mm, not near the connectors for the CCFL's.

[selldoor]

Re: Beko 30inch blank screen after 2 sec.

How about putting up a very clear picture of the inverter board - both sides.
Did the light come back on when you let go of the board?

[HK-Steve]

Re: Beko 30inch blank screen after 2 sec.

No, the backlight did NOT come back ON.

Will post a pic tomorrow, as it is night time here.
Not sure what it will show you, but any help would be great.


Cheers

[HK-Steve]

Re: Beko 30inch blank screen after 2 sec.

Also, all the test point voltages on the connector, were the same voltage,
except for the 24v line, was at 24.2v, not the 23.7v with the CCFL's illuminated.


Cheers

[selldoor]

Re: Beko 30inch blank screen after 2 sec.

Yes i know it sounds odd - we see a lot of boards on here and sometimes spot
problems, even broken traces, that the enquirer has missed. even when he has the board in front of him. The 24v is probably not regulated so will drop slightly when the lights are on.