Topics Topics Edit Profile Profile Help/Instructions Help Member List Member List  
Search Last 1|3|7 Days Search Search Tree View Tree View  

A moment of auction madness!

:: EPE Chat Zone ­:: ­Radio Bygones Message Board :: » EPE Forum Archives 2007-2009 » Archive through 28 March, 2008 » A moment of auction madness! « Previous Next »

  Thread Last Poster Posts Pages Last Post
  ClosedClosed: New threads not accepted on this page        

Author Message
Top of pagePrevious messageNext messageBottom of page Link to this message

mel
Frequent Contributor
Username: mel

Post Number: 56
Registered: 05-2005

Rating: N/A
Votes: 0 (Vote!)

Posted on Sunday, 24 February, 2008 - 04:25 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I did a silly thing yesterday, I went to the local auction, just to have a look around, as you do, and although I had no intention to buy anything, when I went in, I ended up purchasing a 20 inch Samsung (model number 205BW) computer monitor, which as you have probably guessed, when I got it home and plugged it in ………didn't work!

Well I thought it didn't work…….. but on close examination, it seemed that it was working, as I could just about make out the image of my desktop, very faintly in the background, I switched the monitor off, waited about 20 seconds, and then switched it back on again, and low and be hold, I got a nice picture for literally one second, and then the screen went black again. This happens every time I turn the monitor on, nice picture for one second then black screen, & the picture very faint barely discernable. I used to be a TV engineer, 20 years ago,in another life, but I have never been inside one of your modern TFT sets, so have no idea what the problem may be. I was just wondering, if some kind soul could point me in the right direction, as to what to do next please.
Top of pagePrevious messageNext messageBottom of page Link to this message

g6osv
Regular Contributor
Username: g6osv

Post Number: 44
Registered: 05-2005

Rating: N/A
Votes: 0 (Vote!)

Posted on Sunday, 24 February, 2008 - 06:05 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi,if its a flat screen lcd type then it sounds like the inverter for the cold cathode screen illumination is playing up,I have a portsble dvdplayer doing just the same.
Ian (also 20years ex tv engineer)
Top of pagePrevious messageNext messageBottom of page Link to this message

hackinblack
Frequent Contributor
Username: hackinblack

Post Number: 197
Registered: 09-2006

Rating: N/A
Votes: 0 (Vote!)

Posted on Sunday, 24 February, 2008 - 11:59 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

cold cathode? flourescent tube,to you and me but only on LCD monitors NOT on TFT 'TUBE'D ones!
the TFT tubes are almost identical to the good old 'curved' tubes;just a slightly different scanning arrangement.i remember when the first TFT tubes came out,some where failing within months;not impressiveespecially as they where the expensive end of the TV range...judging by the pile of TV's and monitors found at any tip,product lifespan seems to be of minor importance now.
Top of pagePrevious messageNext messageBottom of page Link to this message

mel
Frequent Contributor
Username: mel

Post Number: 57
Registered: 05-2005

Rating: N/A
Votes: 0 (Vote!)

Posted on Monday, 25 February, 2008 - 07:34 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

To clarify things here, then the monitor in question is an ordinary 20" Widescreen LCD Monitor….. sorry if I caused any confusion with my original posting.
Top of pagePrevious messageNext messageBottom of page Link to this message

mel
Frequent Contributor
Username: mel

Post Number: 58
Registered: 05-2005

Rating: N/A
Votes: 0 (Vote!)

Posted on Monday, 25 February, 2008 - 11:53 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I just phoned up the local computer repair centre,regarding this monitor, the conversation went something like this….



Me : I described the fault, as per my posting.

Man in shop: that would be your backlight faulty then.

Me: oh! Can you repair it?

Man in shop: no!

me: I thought you did repairs.

Man in shop: we do, but yours can't be repaired.

Me: do you mean that you can't repair it, or that nobody can repair it?

Man in shop: nobody can repair it mate, you need a new monitor.

Now I have yet to do a search about monitor backlights, but I find it hard to believe this statement, that it can't be repaired…….. so, is the Man in shop right? Or does anybody know differently????
Top of pagePrevious messageNext messageBottom of page Link to this message

arw
Board Administrator
Username: arw

Post Number: 551
Registered: 04-2005


Rating: N/A
Votes: 0 (Vote!)

Posted on Monday, 25 February, 2008 - 12:51 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I would say that any TFT backlight could be repaired... if you can get the spares (tube and/ or inverter). The same problem applies to laptop displays, and I got quite adept at stripping apart my old HP Omnibook (the most unreliable laptop I ever owned) to access the flickering backlight.

I heard the story of someone who swapped out his faulty backlight with a CC light and inverter that PC modders use inside the base unit. Maybe you could grab one out of an old laptop.

The computer shop sounds the sort of place that can fix any software problem -- no problem, mate, I just reformatted your hard disk. Oh, you didn't have a backup? Don't you just hate them?
ARW

Top of pagePrevious messageNext messageBottom of page Link to this message

rob83
Regular Contributor
Username: rob83

Post Number: 23
Registered: 09-2006


Rating: N/A
Votes: 0 (Vote!)

Posted on Monday, 25 February, 2008 - 05:00 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

The following link may be of interest: http://aeminium.org/slug/hardware/lcdfix/

Regards,
Rob
Top of pagePrevious messageNext messageBottom of page Link to this message

obiwan
Frequent Contributor
Username: obiwan

Post Number: 2193
Registered: 12-2005

Rating: N/A
Votes: 0 (Vote!)

Posted on Tuesday, 26 February, 2008 - 12:48 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I'd bet on repairing it also.

THEY don't repair it, probably because there's NO MONEY in it for them. (I would think there is)


First of all, you need to open that thing up, check out the back end of the LCD panel.

You'll see some high voltage wire running to the corners of it, thick insulation, flexible.

Note to where that wire also runs to. You should probably see a small circuit board. I suspect THAT is your problem.

Could also be the tube, or a short, the high voltage shorting out causing the thing to shut down.

Measure out the LCD, and you should be able to purchase a replacement converter board (based on tube length I think) and maybe LCD area.

If that doesn't work, then you can try the tube.

(After checking for shorts, meaning taking the thing apart so it can't short out on anything, and testing it open faced.

Now, if the CPU is telling the inverter to shut down, you have issues. The inverters don't have just +5VDC in/GND and HIV out. They have control lines too.

But, sounds fixable....
Do Not Hit The Fly That Lands On The Tigers Head.
Top of pagePrevious messageNext messageBottom of page Link to this message

echase
Frequent Contributor
Username: echase

Post Number: 74
Registered: 07-2007

Rating: N/A
Votes: 0 (Vote!)

Posted on Tuesday, 26 February, 2008 - 06:12 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

I am currently in middle of repairing a Dell monitor (Benq board) with same symptoms. There was a dry joint on one backlight transformer leg that blew the 2 driving transistors. Waiting for new transistors to arrive. (£20 for 4)

See
http://www.electronicrepairguide.com/dell-e173fpb-lcd-monitor-repair.html

http://www.electronicrepairguide.com/dell-e153fpc-lcd-monitor-repair.html

http://ezinearticles.com/?How-To-Repair-Dell-E173fpb-LCD-Monitor-Easily&id=473931


http://ezinearticles.com/?How-To-Repair-Dell-E153Fpc-LCD-Monitor-With-Shutdown-Problem&id=477057

http://www.josepino.com/other_projects/index.php?howto-repair-dell.jpc

http://www.fixya.com/support/t269485-tried_fix_dell_e172fpb

http://syscon.wordpress.com/2007/07/13/dell-dell-e172fpb-lcd-backlight-repair/


and many others.

I expect you have a similar fault.
Top of pagePrevious messageNext messageBottom of page Link to this message

echase
Frequent Contributor
Username: echase

Post Number: 76
Registered: 07-2007

Rating: N/A
Votes: 0 (Vote!)

Posted on Tuesday, 26 February, 2008 - 11:19 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

The Benq board is used in a lot of models so might be in yours.

My transistors arrrived today from sparesweb.com
Top of pagePrevious messageNext messageBottom of page Link to this message

graham
Regular Contributor
Username: graham

Post Number: 24
Registered: 11-2007

Rating: N/A
Votes: 0 (Vote!)

Posted on Tuesday, 18 March, 2008 - 12:17 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

OPBIWAN and all
In truth have never,ever been to an auction. But it ocurs to me that you need a list of numbers. So when an auction sum announced. You can see from your list. The, commision ,VAT and any other saundries etc. There may be. So that you know the final monies to you. just curious to know how it all works ? ....Best to all...... graham
Top of pagePrevious messageNext messageBottom of page Link to this message

echase
Frequent Contributor
Username: echase

Post Number: 88
Registered: 07-2007

Rating: N/A
Votes: 0 (Vote!)

Posted on Tuesday, 18 March, 2008 - 09:06 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Mel, did you fix it? I fixed mine easily, but then it did have a fault that was exactly as stated on the internet instructions on those links. Rarely is one so lucky as to find this is the case.
Top of pagePrevious messageNext messageBottom of page Link to this message

mel
Frequent Contributor
Username: mel

Post Number: 59
Registered: 05-2005

Rating: N/A
Votes: 0 (Vote!)

Posted on Wednesday, 19 March, 2008 - 07:55 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

If only life was that easy!...... it's taken me a while to get round to doing this monitor because I've had all sorts of problems with my computer , which hopefully is sorted now.
There is no separate inverter board on this monitor, it is all on the main board along with the power supply etc. a lot of the components are surface mount, which is to be expected, and they also have lots of weird and wonderful numbers on the semiconductors, so after checking the obvious components, I decided the only way forward was to get a circuit diagram. I contacted Samsung about this, as I had no luck in getting a circuit diagram (schematic) from the Internet. After being passed from pillar to post , I talked to a man, who told me that no circuit diagrams were available for this monitor, but as this model of monitor had only been manufactured for the last 18 months, then it was still under guarantee, as Samsung monitors are guaranteed for three years, so he wanted my details so that it could be picked up. Well on the face of it I thought this was going to be my lucky day, so having given him the serial numbers, model numbers etc, we of course got to the question of where I purchased it from, as soon as I told him it came from an auction, he told me that as I was not the original purchaser then the guarantee did not apply in this case, which didn't really surprise me.
The problem is however I just cannot get a circuit diagram from anywhere, so there is little more I can do to repair it. I have however decided that I will get one of those cheap, cold cathode kits, that they use for computer case lighting, and see if I can make my own backlight using these. They only need a 12 volt supply which I can tap off from the monitor power supply, so I will see what happens and then post the outcome back here.
Top of pagePrevious messageNext messageBottom of page Link to this message

echase
Frequent Contributor
Username: echase

Post Number: 89
Registered: 07-2007

Rating: N/A
Votes: 0 (Vote!)

Posted on Wednesday, 19 March, 2008 - 08:11 pm:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

http://www.eserviceinfo.com/

Have you tried this site? I find it is by far the best source of free circuit diagrams and manuals. You might find something similar even if not your exact model. You need a RAR file reader like WinRAR for many of the downloads.
Top of pagePrevious messageNext messageBottom of page Link to this message

externet
Frequent Contributor
Username: externet

Post Number: 121
Registered: 05-2005


Rating: N/A
Votes: 0 (Vote!)

Posted on Thursday, 20 March, 2008 - 12:28 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

Hi mel.
Repared half a dozen of LCD monitors, mostly bad electrolytic capacitors in the inverter section and worn out cold cathode flourescent tubes.
The last one I discarded the fluorescent tube and inserted a row of ~30 white surface mount leds, fed by 12V; discarded/disabled the inverter, and works happy.

The problem is the spares co$t is senseless, they want to wring your wallet for more than the monitor is worth. If you love the monitor, rig a led backlight that works and have fun doing it.

That is the future of many lcd televisions, dying because a stupid/cheap/short-lived design backlight failure.

Miguel
Abolish the deciBel !
Top of pagePrevious messageNext messageBottom of page Link to this message

mel
Frequent Contributor
Username: mel

Post Number: 60
Registered: 05-2005

Rating: N/A
Votes: 0 (Vote!)

Posted on Monday, 24 March, 2008 - 11:39 am:   Edit Post Delete Post Print Post    Move Post (Moderator/Admin Only)

First of all, Thank you to everybody for their valued comments. I finally managed to get a bit of time to have another look at this, and as explained previously, I decided to experiment with the cheap, cold cathode lighting kits that are used by some people to light the inside of their computer cases.
Having brought the 12 volt inverter and two cold cathode tubes, I decided that I would connect the inverter to the existing cold cathode tubes, to determine whether the tubes were faulty or not. There are six tubes in this monitor, so I tested each one in turn, using the new inverter, I had to turn the input voltage up to around about 16 volts for the Tube to strike, I then turned down the voltage to around about 14 volts to produce a steady light from all six tubes in turn. Having established that the tubes seem to be okay, I decided to light up two of the tubes, when I had put the monitor back together, just to check that the monitor was indeed working and no other problems, bearing in mind that I had never seen a picture of this monitor as I purchased it faulty. I reassembled the monitor, and plugged it in again, and of course I had the original fault, i.e. no backlight and faint picture. I then connected the middle two cold cathode tubes to my inverter, and was rewarded with a picture, of sorts, albeit rather dim. This gave my hope that the faulty backlight could be repaired using two or three of the cheap inverters. However I noticed that the bottom third of the screen was now showing vertical lines of different colours, so I decided, to investigate further. At this point I reconnected the six plugs that are attached to the six cold cathode tubes back into the sockets on the inverter, and then switched the monitor back on, to my surprise, all six cold cathode tubes lit up, and I had a decent picture on two thirds of the screen but the bottom third as stated previously had vertical lines. At this point, memories came flooding back from my previous life as a TV engineer, and of the frustrating problems that one can get for no rhyme or reason, as to why this type of problem should be happening, why did the backlight tubes start working again? I did not see the vertical lines, when I first got this monitor, although the backlight wasn't working, I could still see a faint picture, and don't remember these lines at all.
I have now once more run out of time today, and will look at it again over the next few days, but if anybody has any comments that may help me, then they would be much appreciated.

Administration Administration Log Out Log Out   Previous Page Previous Page Next Page Next Page