Samsung SyncMaster T240 - broken cclf lamps - Page 1
Forum section: electronics / repair

author: thelole
author_rank: Newbie
timestamp: October 29, 2015, 10:14:59 pm
content: Hi,Today i bought a broken T240 monitor in the hopes of easily fixing it by replacing a few caps. The display problem was that the picture died about 2 seconds after showing picture. I did notice the light was very weak as well.When I took the monitor apart it turned out that a pair of cclf lamps was broken (some yellowish liquid spilled around the area as well).I searched ebay for replacement lamps and didn't get many results but I did find some replacement LED strips that would work even better if they fit.So my question is: does anyone know whether these strips will work for my display? I do know the width of 540mm is correct. There is some explanation in the description of the item but I don't understand this broken Chinese English...Link to the led strips:http://www.ebay.com/itm/540mm-LED-Backlight-Strip-Kit-Update-24-24-inch-CCFL-LCD-Screen-to-LED-Monitor-/271935872599?hash=item3f50a41e57:g:yiwAAOSwMmBVp3UXMy second question is: When googling I noticed that about 99% percent of people that had this 2 second blackout problem sorted it by replacing the transformer. Now is it possible that the in my case the transformer is also broken and it's causing the 2 second blackout or is it plausible that this blackout is caused by the shattered cclf alone?Thanks for your help guys!

author: rf+tech
author_rank: Frequent Contributor
timestamp: October 30, 2015, 02:20:40 pm
content: Hi thelole,First, to address the 2 second blackout problem. The high voltage inverter that drives the CCFL monitors the current flowing through the lamps. When the current sensed is incorrect, the inverter shuts down. Two broken lamps implies the sensed current is not what the inverter is expecting, so replacing the transformer will result in some disappointment. Personally, I have seen 10 or more broken CCFL, in Dell Ultrasharp displays with four lamps each. In each case, they appeared to have failed from excessive heat right next to the metal end electrode.Second, LED strips cannot be directly substituted for CCFL as each requires differing drive requirements. CCFL inverter output can be up around 1.5 kV to 1.8 kV at only a few milliamps. LEDs requires an order of magnitude or so more current at a much lower voltage.The easiest repair would be to order new CCFL from Mouser or Digikey. If you feel adventurous, it may be possible to substitute lamps from another LCD panel, even if they are a CM or two shorter than the original.Since you have already disassembled the panel and removed the lamps, you'll have some idea about how fragile CCFL are to handle.

author: PolPot
author_rank: Newbie
timestamp: October 28, 2024, 12:51:55 am
content: I´ve just installed the AliExpress generic LED retrofit kit in my Samsung T240N monitor.The removal of the CCFL lamps and placement of the LED strips is straightforward, just remember to route the cables just like the original CCFL cables.In the IP board I removed F301 to disable power to the CCFL inverter and connected the DIM/ADJ line to pin 1 (PWM_DIM), VCC to pin 2 (13V IN), GND to pin 5 and ENA to pin 9 (BL_ENA). Working better than new.Cheers.

author: wraper
author_rank: Unknown
timestamp: October 28, 2024, 01:03:00 am
content: It's good that you got monitor working, however you will need to enjoy screwed up color reproduction. Unless you don't care how colors look like, replacing CCFL with LED is not a good option at all. Regardless of which LED strips you'll get, their spectrum will be way off of what LCD panel is tuned for.