Mulja tv repair portal
Equipment Repairs => LCD TV forum => Topic started by: 200sx on January 07, 2011,14:21:16
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Hi everyone. Been searching for a repair forum for ages and stumbled across the site yesterday, and I must say that you all seem a very friendly, helpful bunch :thumbup:
Been out of the repair game for 15 years so I know nothing about LCD. I've now bought a new TV but thought I may as well try and repair the Samsung instead of binning it.
The set is 3 years old and the problem started about 6 months ago. Initially all the peak whites started to crush and flare. I found that if I came out of Dynamic mode and backed off the contrast a bit, the picture was again acceptable, but not as good as before. I tried the service reset at this time but it didn't improve things. Things remained steady until about 10 days ago when the picture brightness suddenly halved while watching it. If I turn brightness up full, backlight full and contrast around 75, the picture is watchable but poor during dark scenes.
I've read loads about PSU capacitors failing prematurely and taking the eeprom with them. Do you think its worth replacing these? Can they cause problems as discribed? I'm still handy with a Fluke and a soldering iron - just lack the modern theory !!
TIA
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hi
do any of the elcos in psu look like
they have started bulging if so change
them and see how the pic looks then
dave
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hi
do any of the elcos in psu look like
they have started bulging if so change
them and see how the pic looks then
dave
No, they don't - was the first thing I checked. Is it generally the 2 1000uf and 2 1500uf that cause probs or can it be any? I don't mind ordering a bucketload if it could be worthwhile ! Would be a cheap and easy fix :c017:
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hi
have you checked the lead to screen drive panel(tcon)
post a pic of fault
dave
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hi
have you checked the lead to screen drive panel(tcon)
post a pic of fault
dave
Sorry, I'm a bit lost with LCD jargon. Could you tell me which lead you refer to? As I said in my original post, although I was a repair Tech for 25 years, I haven't kept up with TV technology (work in IT Support nowadays). This is the first time I've ever had the back off an LCD lol.
The TV is in bits at the moment so I can't post a piccy of the fault. The picture is worse at switch on - dark but watchable. When its been on a while it gets very slightly brighter (but still not really acceptable). Contrast has to be backed off quite a way otherwise any peak whites flare out - like an over contrast situation - the flare becomes green tinged - sort of a glowing effect.. Had it been a CRT, I would be checking A1 voltage to see if I could wind it up a bit.
I really appreciate any advice you could give, but treat me gently, its been a while :93:
cheers
Dave
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hi
its the thick cable coming from main panel to
the lcd screen it fits into the tcon panel
dave
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hi
its the thick cable coming from main panel to
the lcd screen it fits into the tcon panel
dave
OK thanks. Bit too late to start tonight. Will have a look tomorrow and report back. Do they go dry or oxidise or something?
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hi
oxidise be careful sometimes they glue them in
dave
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Right then. Tried removing plugs and cleaning - unfortunately no better. I have posted these images (hopefully) so that you can get some idea of what I am faced with.
http://www.flickr.com/photos/58058077@N05/?saved=1 (http://www.flickr.com/photos/58058077@N05/?saved=1)
Was unsure about posting images so please advise if they can't be seen or if there'e a better way.
thanks
Dave
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hi
you could try changing eeprom ic
dave
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hi
you could try changing eeprom ic
dave
OK thanks. Could you tell me the location please? Is it on the PSU board or the tuner i/o board?
cheers
Dave
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Oh and by the way, I may as well change the PSU caps, which are the usual ones that give probs?
cheers
Dave
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hi
its on the motherboard printed circuit mounted 8 pin
chip it says on pcb eeprom
dave
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Right then. Found the eeprom, put a switch across pins 5 and 6 and tried the reset. Pretty sure I followed all the instructions to the book but the picture is just the same as before, so I'm now feeling more grumpy than usual :03:
If this had been a CRT I would say that the tube was knackered. I think I'm gonna call it a day and get someone local to have a look and tell me whether its worth repairing.
I'm not really bothered if it goes in the skip, - got a new Sony, its just a shame if it only needs a cheap repair !
I just wish I still had one or two contacts in the trade that would give me an honest opinion. At the end of the day I'm like most people, don't mind paying for someone's time but don't wanna be ripped off, and its not really worth spending much on it.
Thanks for all your help.
Dave
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I fixed a 40" one of these before Christmas by swapping out the caps and just reset the eprom but I didn't feel the picture quality was as good as it should have been, mainly too dark. However I'm not a good judge of pic quality on lcd's so just accepted it. So I'd be interested in understanding whether swapping out the eprom would make a difference as logically it shouldn't if the set comes on and retains its settings.
Cheers
rob
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I fixed a 40" one of these before Christmas by swapping out the caps and just reset the eprom but I didn't feel the picture quality was as good as it should have been, mainly too dark. However I'm not a good judge of pic quality on lcd's so just accepted it. So I'd be interested in understanding whether swapping out the eprom would make a difference as logically it shouldn't if the set comes on and retains its settings.
Cheers
rob
See I haven't had any power problems - just the gradual deterioration of the picture. I thought about changing caps, but I really don't think its that. Just wish I had a bit more understanding of LCD circuitry. I just dont understand what TCon board does or what an inverter does. :17:
25 years of repairing CRT technology / VHS / Sat Receivers means nothing nowadays lol :wink1:
Dave
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hi dave
had lots of problems with screens on 37inch sammys, would try changeing the tcon pcb first just in case its that,
good luck
daz
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hi dave
had lots of problems with screens on 37inch sammys, would try changeing the tcon pcb first just in case its that,
good luck
daz
Sounds expensive :(
Dave
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Just an update for your information. Had a local guy have a look at the TV and it was indeed the Tcon board. Not quite back to new standard, but good enough, and at £95 all in, it will do for my son when he moves into his new place.
thanks all
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What you got a screen inside ?? Regards