Samsung Le40c530f1w

[ron77]

Working on Samsung lcd tv found out a few things that could be of interest. At least could save time and money. Plugged in tv, came on normally, chimes etc. Backlights went off after couple of seconds, sound stayed. Disconnected CN802, backlights came on normally.Fitted replacement main board,made no difference. Wasn't surprised actually.
On Cn802 removed leads 2,4 and 6. Backlights came on instantly. Pic and sound ok. Connected leads 2 and 4 back into plug, so only had lead 6 disconnected.With only lead 6 disconnected backlights came on normally, that is after chimes finish. pin 6 on plug is E-PWM. Obviously, backlight intensity cannot be varied, but is normal. Backlight intensity does not vary. Have ordered psu from emos, probably where problem lies, should arrive after the holliday. Have had little to do with the forum lately, because of a triple heart by-pass.

ron66

[etronic]

Re: Samsung Le40c530f1w

possibly inverter on it's way out or CCFL draws too much juice on high level of backlight....

[ron77]

Re: Samsung Le40c530f1w

etronic,
Your thinking appears same as mine. Have ordered psu/invertor panel,bn44-oo340a. If that doesn't cure problem, then ccfl's are about all that is left. I wrote this one up because when main board disconnected from psu/invertor board, and backlights work, some say suspect main board. It probably mostly is that, but not always.

[budm]

Re: Samsung Le40c530f1w

"I wrote this one up because when main board disconnected from psu/invertor board, and backlights work" If the backlights stay on in this mode, then the power supply/inverter/lamps are OK.
Pictures of the board? Is there cable between the T-CON and the Inverter board?

[tom66]

Re: Samsung Le40c530f1w

There's a small chance that the bulbs are wearing out, if the main board sends a dimming command, it could cause the worn out bulbs to extinguish.
It is a 2010 TV though, I would be surprised to find bad bulbs, unless it's very well used.

[ron77]

Re: Samsung Le40c530f1w

to budm and tom 66.
There is no connection on this model beetween t-con and invertor board,but understand why you asked. with regard ccfl's, they do seem ok. Not able to send pics at moment,but good pics available at emos lcd spares and flat tv parts. realise now could have explained better. tv works perfectly when pin 6 is disconnected from cn802 plug. Connect pin6 and you get 2 sec to black. the voltage coming from main board on pin 6 moves backlight intensity up or down.The voltage varies from .9v to 5.3. Problem is connect pin 6 and off go the backlights.Have ordered psu/invertor panel and will report if it cures problem.With pin 6 diconnected, the only way you can tell there is a fault is to try and vary backlight intensity. The backlight cursor moves up and down, but that is all. ron77

[budm]

Re: Samsung Le40c530f1w

The E-PWM is the 200 Hz (about) variable pulse width for dimming control, 90% width is full brightness, 10% is for min brightness. You can look up spec for the full info if you can get the LCD panel model number. There may be problem with the inverter circuit then if the PWM signal is correct.

[tom66]

Re: Samsung Le40c530f1w

Did you try to turn off the dynamic mode, and set it to standard mode instead?

[ron77]

Re: Samsung Le40c530f1w

Tom66,
No, i havn't. Will check that out tomorrow. Tv is now, with back on, waiting for psu/inv. Can tell you one thing though, did replace most caps and did work ok for a while, thought I had cured it, but I hadn't. possible that something is slightly out.
Ron77

[ron77]

Re: Samsung Le40c530f1w

Tom,
Tv already in standard mode. Tried dynamic mode, and other modes, tv insists on working perfectly unless connect pin 6 on cn802. Yes, tv is 2010, may is the month. Panel will probably arrive wednesday. Logic tells me it is fault on psu/inv panel,but sometimes logic doesn't help.

[ron77]

Re: Samsung Le40c530f1w

budm,
Sorry, didn't realise you sent in new communication. Pity because was very informative. Myself have no technical info on this particular model. I did replace mainboard, made no difference. It was 2am here in england, didn't spot your comments until after sent message to tom this morning.Like your theory, it does say fault in inv. could cause this problem. As I write this, tv is still working perfectly.
ron77
p.s. will inform how I get on when panel arrives.

[ron77]

Re: Samsung Le40c530f1w

Psu/inv panel cured problem,thanks for the help.

Ron77.

[ron77]

Re: Samsung Le40c530f1w

Tested for many hours but backlights went off. Maybe something on panel, a ccfl for instance. Is there a modification for this model.At this moment I don't know the answer. Remove pin 6 on cn802 still works Ok. Let cool down overnight backlights will not come back. Remove pin 6 and backlights work perfectly.
Ron77

[tom66]

Re: Samsung Le40c530f1w

It is most likely worn out bulbs.
The only fix is to force the backlight to max brightness.
I don't know how long that will last but in the case of one monitor I had, it lasted over 2 years before I sold that monitor...

[ron77]

Re: Samsung Le40c530f1w

Tom,
What you suggested made me think. First, how do I force backlights to maximum. On pin 6 the voltage moves up and down when backlights moved on pic. menu. High volts 5.29. Low volts .78. That is on pin 6 disconnected from psu/inv. Comes out of main board. Putting backlights to max. reading on main board 5.29v, reading on psu 5.27v. So backlights should be maximum when pin 6 disconnected.Seems already done what you suggested. By accident, not design.Next thought was resistor that supplies 5v. could have gone high value. As I have changed psu/inv and main board it would have to be on slim board on lcd panel. Probably not, but will check it out.Voltage does fall to 1.6v when backlights set at maximum, and pin 6 connected up correctly.
Ron77.

[ron77]

Re: Samsung Le40c530f1w

Found problem, was a ccfl flickering. Reasonably certain it was only one of the twelve. After a lot of testing, fault became worse, backlights shut down with psu disconnected from main board. Could get tv back working by removing rf 804, which made protect circuit less sensitive. After this, noticed slight flickering on screen, only on the seventh lamp from top. Next step, looked through lcd tv's with cracked screen's, to find similar ccfl. Havn't got that many of them, so surprised to find had same model. So replaced the backlight assembly, saved a lot of work. Job done. If I had known that tv was there it would have saved me a lot of time and money.
Ron77