14 replies to this topic

[Jammy]

I've already fixed my TV/Monitor once after something blew a whole load of caps, shortly after a thick black band appeared down the side of the monitor. I've put up with it for months, but now I'm getting a second band appear right next to the first, of equal thickness. At the moment this second band is just flickering, and tapping the top of the monitor makes it dissapear, so I'm thinking its a dodgy connection somewhere...

Anyone know of this problem before, and how I might go about a solution?

[Silicon Skum]

Is this a CRT or LCD?

LCD is harder to fix (not impossible, but harder for a novice to fix) and it also depends on what the problem is, ie controller or ribbon cable etc.


When you say you replaced the caps, did you replace them with the IDENTICAL replacement parts? It's very possible that cheap, substandard or incorrect tollerance / value parts can be causing this. Also I would be more interested in finding out what caused the caps to blow in the first place, this may be the cause of the problems you see now. Have you checked the PSU voltages are with in tollerance?


SS

[dave20046]

Is this a CRT or LCD?

LCD is harder to fix (not impossible, but harder for a novice to fix) and it also depends on what the problem is, ie controller or ribbon cable etc.


When you say you replaced the caps, did you replace them with the IDENTICAL replacement parts? It's very possible that cheap, substandard or incorrect tollerance / value parts can be causing this. Also I would be more interested in finding out what caused the caps to blow in the first place, this may be the cause of the problems you see now. Have you checked the PSU voltages are with in tollerance?


SS

Sounds reeally daft but you have tried just pressing the auto adjust function haven't you?
Edit: sorry just read the bit about tapping it temporarily fixing it, very unlikely that would help ^

Edited by dave20046, 31 December 2007 - 05:46 PM.

[Jammy]

Yea, its not auto adjust.

Yup, replaced them with exactly the same caps, had to pay for 10, only a few quid, and the postage was about 3 times the cost of the caps!

Its LCD, haven't check the PSU voltages, how would I go about doing that?

[Silicon Skum]

Its LCD, haven't check the PSU voltages, how would I go about doing that?

It depends on if the PSU is external or internal. First off, check the sticker on the back of the set, or check the manual / google search for the spec sheets from the manufacturer. If the PSU is external 'brick' type, then the details *should* be printed on a sticker there. Then use a multimeter to check the voltage levels are within a reasonable tollerance (about half a volt up to 1 volt from that listed).

If you have no information on the psu, only real check you can do is to check that the voltage output is stable and isn't fluctuating rapidly. Diagnosing and fixing PSU troubles will be outside of what I can help you with - you will realy need to know about switchmode PSUs before attempting anything.


Looking at the picture of your display, I'm not entirely sure what the problem is, but it looks as if at least one section is having timing sync problems. The black section seems to be not getting any signal voltages. I would say there is a strong possibility that this is controller problem - BUT it might only be a simple broken connection to / from the LCD panel ribbon cable.
Crack the case open, and trace the ribbon cables attached in the faulty area of the screen, back to the controller board (depending on the controller type, there may be one or multiple controller chips). check the ribbon cable for damage, remove from the connector (CAREFULLY) and clean the contact area of the cable with alcohol and re-insert. then power up the display and check for progress.


The LCD panel section *may* have to be dissassembled - NOT easy as there are numerous small screws. There will probably be another connector for the ribbon cable(s) inside the metal screening around the LCD, and this attaches directly to the LCD panel - clean and reconnect. check progress.


Give things a tweak while the monitor is operating and see if any changes happen - this will let you know if it's a simple loose connection (may be a bad solder joint etc).


BE CAREFULL!! the voltages used to power the backlight are VERY high - the current is quite low, and prolly not enough to kill you by any means.......BUT IT WILL HURT LIKE HELL!
Voltages used to power the LCD panel are low, so no shock risk - just avoid the backlights and inverter.



If the controller is gone, it's time for a new monitor - you prolly will not be able to buy the module to replace it. Manufacturers tend not to be willing to sell repair parts to the public.
If you can find a repair company, then they will prolly be able to order the parts and fix it cheaper than a new monitor. Not THAT much of a price difference though.

Give it a try, and report back what happens - I'll try to figure out what the deal is (though fixing a monitor without actually seeing it, is difficult to say the least!).

[Jammy]

The PSU is an external brick. The output is listed as 12V = 5.0A 60W Max. Which parts do I connect the multimeter terminals to? The connection into the brick is a kettle connector, the other end is a hollow cylinder like (pin?) connector.

I'll print off your post and take the monitor apart this evening...

EDIT: Worked it out, just started sticking my terminals in several places. The voltage at the pin connector is 12.34V.

[MiNi FiZ]

fair play if you can get it to work, but if you cant save yourself the hassle, get a new monitor, it'll probo. cost you more to repair it... i'll be watching this thread...

[*Raz*]

get a new one



Be careful, I dont want you electricuting yourself, kids and electronics don't mix and Raz is not there to supervise x

[Jammy]

Yea, i've been thinking of getting a new monitor for a while now but:

Last time this monitor broke (the 'ON' LED would just bleep on and off, and the monitor wouldn't turn on), I thought I might as well have a go at repairing, since it doesn't work now, I haven't got anything to lose. Back then I was looking at about £150 to get a decent spec monitor. The capacitors I ended up replacing cost me about £8, so all in all I saved myself well over £100!

[*Raz*]

Yea, i've been thinking of getting a new monitor for a while now but:

Last time this monitor broke (the 'ON' LED would just bleep on and off, and the monitor wouldn't turn on), I thought I might as well have a go at repairing, since it doesn't work now, I haven't got anything to lose. Back then I was looking at about £150 to get a decent spec monitor. The capacitors I ended up replacing cost me about £8, so all in all I saved myself well over £100!

LOL!!

Well you've been gone for a fairly long time now. . . . . I think you've broken it

x

[Jammy]

Have not!

I did discover the cause of the problem though. There is a very thin circuit board that is connected to the LCD glass panel at the top, which I'm guessing basically feeds the electrical signals down the monitor, to produce each pixel. Well the Circuit board is connected by a series of filmsy films, and the right most two of these, the contacts have detoriated, I tried sellotape over them, as well as re-soldering the two tabs at the side that hold them to the board, all without success. I'm going to look out for a cheap monitor on Ebay for spares or repair, then switch the panels over.

[Silicon Skum]

There is a very thin circuit board that is connected to the LCD glass panel at the top, which I'm guessing basically feeds the electrical signals down the monitor, to produce each pixel. Well the Circuit board is connected by a series of filmsy films, and the right most two of these, the contacts have detoriated, I tried sellotape over them, as well as re-soldering the two tabs at the side that hold them to the board, all without success. I'm going to look out for a cheap monitor on Ebay for spares or repair, then switch the panels over.

Ahhh, yep that would do it! Looks like either something has scratched along the tracks, or part of the case has been incorrectly closed / pressing too hard on that area.

That CAN be fixed........but it's a REALLY fiddly job (I know - I've done it a couple of times before!)

Basically what you need is very low temperature SMD solder paste, you then spread a thin line over the damaged area, then heat with a hot air gun (really it needs some kind of heat plate behind, but it's not good for the LCD. The solder paste will seperate and only join the tracks, not short everything together. Good stuff.

Another method I've used, it to use a long thing needle to move the tracks around and close the gap in the tracks and hold it there, then apply a conductive ink (similar to the stuff used to repair rear windscreen heaters) using another needle dipped in the ink, and deposit a small drop over the repair (avoid getting it between the tracks / shorting out tracks). hold until the ink has dried - usually a couple of mins at room temp. Then repaet for each track.


I have a very nice colour electroluminescent display that has a tear in a ribbon cable (right in the middle and cutting several tracks), I've been trying to fix it for years. Problem is I have not found a way to bridge the gap between the tracks (VERY small and VERY close together), and it requires a microscope and steady hand to even work on it. I'll get it done one day.



by the way, if you are going to chuck that monitor, stick it on fleabay in seperate parts (case, logic board, backlight tubes etc.) and you should make a little cash back.

SS

[Jammy]

Well I was looking on Ebay and someone bought exactly the same monitor as mine for spares or repair for £30 2 days ago! I've got a saved search so hopefully something will come up soon. I think I damaged something else when I was putting it all back together, the whole monitor has a slight reddish tinge to it! I managed to get round it mostly by changing the temperature, but its still not quite right. Worst comes to worst I'll just buy a new/2nd hand monitor, only drawback is mine has a built in TV tuner, so the next one will need that too, and they aren't that common, or cheap!

[Silicon Skum]

the whole monitor has a slight reddish tinge to it!

Backlight bulbs are getting old, they begin to go red / pinkish as they age. Prolly not a lot of life left in them, easy enough to replace though (can even use white LEDs).

You can get TV / monitor combos fairly easy, problem is they tend to be more TV spec than monitor spec (slower LCD pixel clock( around 12 - 16ms), so images tend to have motion blur, where as monitors are 5ms or less typically), so not much good for games with fast action.

What about just getting a TV tuner card for the computer, and spend the cash on a decent spec monitor for the same cost?

SS

[Jammy]

Sorry, I meant its only got the red tinge to it after I put it back together last night. Hopefully I haven't aged the backlight in one evening! lol Also found out last night that the tuner card no longer transmits any image to the screen, so gotta take it apart and see if there is a dodgy connection.

Currently watching several options on Ebay. I had thought about a tuner card for the computer, but I like to watch TV in bed, and I'd have to leave the computer on, etc. I know there are solutions I could use to turn off the computer, but its just simplier for me if the LCD has a built in tuner.