Monitor PSU and backlight - Page 1
Forum section: electronics / beginners

author: amemic
author_rank: Contributor
timestamp: August 21, 2015, 12:20:13 am
content: Hello!wasn't sure is this a beginners question or not...Anyways...I got a monitor for a $5, 19" Benq FP91G+, got it on a market outside, and wasn't able to test it....so I hoped I got a good one...but well Murphy says no...good thing is, it does work, but with shattered matrix it's pretty much no good...as it was darn cheap so I wanted to do something with this thing...I usually need a good lightning for my camera when doing macros, so I figured, let's get rid of broken matrix and make a nice uniform light sourceI figured out how to turn on the power supply, and it worked it turns on backligh nicely, but the thing shuts it off after few seconds...I thought the sleep mode is in the main board, but apparently it isn't...Now, I made analysis, it seems that it runs on 5V, and when I power on with all the electric connected, it gives 5V to a brown wire, an 3.3V on a black wire...when it goes to "sleep" it shuts off 5V from the brown wire and goes to 5V on the black wire...Does anyone have any experience with things like this? How to force it in permanent on mode? should I just drop a resistor on a black wire to drop the voltage to 3.3V or am I wrong?Pictures are attached, you can see nicely shattered matrix (someone did a nice job), and the power supply as it is...

author: rickselectricalprojects
author_rank: Regular Contributor
timestamp: August 21, 2015, 10:38:23 am
content: you could try a voltage divider like the one i attached. hopefully that works

author: amemic
author_rank: Contributor
timestamp: August 21, 2015, 11:44:04 am
content: I just tried it...nothing...same behaviour...Maybe it need some other signal...Or should I just rip apart two of those energy saving bulbs and, put a nice flip flop there to switch the mains on/off via relay and just get it over with...

author: amemic
author_rank: Contributor
timestamp: August 21, 2015, 12:08:10 pm
content: Maybe just to rip apart those buls and make something like this...I haven't been doing this since high-school so forgive me if I made any mistakes that burn your eyesOh yea, btw. How can I remove that polarizer foil from the glass? how to remove that nasty glue that holds it, I want to try to use that as a polarizer filter for my camera just to see the effects :-)

author: Isad
author_rank: Frequent Contributor
timestamp: August 21, 2015, 01:49:13 pm
content: If i am right there must be a smd chip underneath the board orat least 1 chip driving them they generally have on/of and dimm options

author: amemic
author_rank: Contributor
timestamp: August 21, 2015, 02:08:38 pm
content: Well yes there is...OZ9938GH...I did a google search but for now I haven't found useful datasheet...Those two black and brown wires are connected to that chip but without datasheet I can't do muchEdit:I've found the data sheetNow, I guess that I should put the ENA pin to high, but I haven't completely got the idea of the TIMER pin...

author: Isad
author_rank: Frequent Contributor
timestamp: August 21, 2015, 04:14:59 pm
content: Quote from: amemic on August 21, 2015, 02:08:38 pmWhy would you even need the timer pin isnt it connected to the board anywereand you would only need to care about ENA and DIM thats the one u will want to look after.Pls dont go over 2v by the DIM pin its breaks the hole thing.And btw the datasheeet says why there is the timer pin its for delaying the shutdown and ON of thelights.

author: christos
author_rank: Regular Contributor
timestamp: August 21, 2015, 04:27:13 pm
content: why not use led strips?? better light,low power,,you just need to find a source on the board that can power up the led's.. i got a monitor for free,22" widescreen with CCFL ,(LCD),,,the driver board was burned so i replaced it and removed the CCFL tubes and put some led strips in there,,and now i got a nice led monitor,,hope that helps

author: Isad
author_rank: Frequent Contributor
timestamp: August 21, 2015, 04:33:00 pm
content: Quote from: christos on August 21, 2015, 04:27:13 pmHe doesnt want to get it back workign agian i bealive hejust wants to use the ccfl for light source.

author: christos
author_rank: Regular Contributor
timestamp: August 21, 2015, 04:41:42 pm
content: yea,,the thing is ,if he cant do that,,its easier just to remove the ccfl and put leds in there,,find a voltage source thats always on,put a switch and done. total cost will be like 5$

author: Isad
author_rank: Frequent Contributor
timestamp: August 21, 2015, 04:50:11 pm
content: Quote from: christos on August 21, 2015, 04:41:42 pmYep works.

author: amemic
author_rank: Contributor
timestamp: August 21, 2015, 09:55:31 pm
content: Yeah I know all...hehe, I just wanted to use these ccfl inside...I have bunch of white PLCC2 led's for something like that, but, I have two perfectly workying tubes inside, so I think I'll make something of those used energy saving lampsI already did something similar with ccfl from an old scanner...