E152FPc Dell - Page 1
Forum section: electronics / repair

author: Jasonbit
author_rank: Regular Contributor
timestamp: July 17, 2018, 11:47:44 pm
content: Hello folks,I am newbie on all this stuff. I intend repair this monitor Dell E151FPb - LCD monitor - 15" (https://www.cnet.com/products/dell-e151fpb-lcd-monitor-15/specs/). I plugged the power cable and it is turn on the lamp in main button but any lighter come through LCD. I open the box and I checked if the terminals where two fluorescent lamp has tension, but with my meter I can't measure anything. Maybe I need connect all stuff to have any tension on this terminals...I don't know. On this link I underline to the two terminals where the fluorescent lamp connected (https://snag.gy/i6DICQ.jpg).After I googled and see some videos on internet let me know what I need to test the fluorescent lamp is a frequency inverter. Right?Also I search about course to learn more about repair LCD and I found many links and courses. But I don't know which is the best option. What course, book, or channel on youtube to learn more about repair LCD?Thanks

author: LateLesley
author_rank: Frequent Contributor
timestamp: July 18, 2018, 12:06:41 am
content: A lot of the time I've looked at monitors with no backlight, it was usually the switching FETs in the backlight inverter circuit that had failed. I would first be looking over that circuit for any obvious faults,, before suspecting the CCFL. You could probably test the lamp, using a known working laptop backlight inverter board, and running it off a 12V supply.

author: Jasonbit
author_rank: Regular Contributor
timestamp: July 18, 2018, 08:24:33 am
content: I found this circuit:https://svbitec.files.wordpress.com/2013/09/lavas-57.pdfWhat do you think about I build this schematic and try test my CCFL with this?Meanwhile I searched on ebay and I found this:https://www.ebay.com/itm/CCFL-Tester-LCD-TV-Monitor-Laptop-Screen-Repair-Backlight-Lamp-Test-MAX-700mm-/160702217893?_trksid=p2349526.m4383.l4275.c10#viTabs_0I can't know if this kit have connector to this terminals:https://snag.gy/zniEt8.jpg(terminals on my LCD monitor).

author: LateLesley
author_rank: Frequent Contributor
timestamp: July 18, 2018, 08:43:53 am
content: Well, you could build that circuit, but you'd still be faced with the connector problem. And I'm not sure that circuit would be healthy for the CCFL under test, as it looks like a "quick and dirty" design. There's no real monitoring of the CCFL current or anything. it's just applying a high voltage AC across the tube.I think the tester you linked would be more suitable. And I think the adapter cables may fit your screen, the wide ones with the center pin disconnected. I can't guarantee it, but it looks like chances of it fitting are high.

author: Jasonbit
author_rank: Regular Contributor
timestamp: July 18, 2018, 10:11:21 am
content: Thanks to your help.Yesterday I applied on monitor terminals 30VDC (before I googled about how should I turn on monitor/lcd) On my supply source I didn't see any current be pulled by the monitor. Could it have killed the monitor?

author: LateLesley
author_rank: Frequent Contributor
timestamp: July 18, 2018, 05:19:33 pm
content: Do you mean in the backlight? If so, it's probably ok, 30V wouldn't get to a strike voltage, So you should be ok. But I would suggest that randomly applying voltages to parts is not the best way to test them.Datasheets first. And learn what they require power-wise, THEN make sure they get powered with something appropriate. Most electronics let out the magic smoke due to not being powered properly.

author: Jasonbit
author_rank: Regular Contributor
timestamp: July 18, 2018, 11:24:26 pm
content: Yes, on this terminals (https://snag.gy/i6DICQ.jpg)Howww...I searched in monitor body for references or words and I got the reference for this datasheet (http://www.beyondinfinite.com/lcd/Library/LG-Philips/LM150X08-A4K3.pdf) On page 7 we can see the electric characteristics about Lamp and howw. I will need 560V with 8mA at a frequency of 60kHzThanks

author: LateLesley
author_rank: Frequent Contributor
timestamp: July 19, 2018, 01:57:49 am
content: and that is what the inverter tester does - it'll generate those voltages and currents from a 12V supply. invest in the tester, its cheap enough - but really, you should just meter out the inverter components. it is common for the inverters to die. the CCFLs do go too, but its less common, unless there is physical damage. And if it is dead, it's time for a new screen really, unless the ccfl is easily accessible. But they are fragile, and easy to break, when trying to replace them.

author: Jasonbit
author_rank: Regular Contributor
timestamp: July 19, 2018, 08:19:03 am
content: I tried open all set monitor and I discovered this piece is composed for several piecesI am trying talk with vendor to discover a cheap and compatible tester. Thank you for your advice.On output inverter I haven't values. But I will mount all set to ensure all input and output is apply as a whole. I need learn more about (continue studying) "how repair monitors...."