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Thread: Dick Smith 37" LCD TV Green screen problem

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    Default Dick Smith 37" LCD TV Green screen problem

    I am a first timer, I looked thru all topics and I didn't find any topics that covered LCD TV, so I am posting my question here in general Chat.

    I have a Dick Smith 37" GE6804, LCD TV.
    Last few month, LCD screen changes to green overall out of nowhere, but I can still see the picture but all in green, not multi-color anymore.
    So I unplug power cable then re-plug (hard re-set), now screen returns to original multi color picture.
    This happened about once a week for few months then last week everyday, even few times a day.

    Questions?
    Is LCD going bad? Maybe control board chip is going bad?
    Will this continue (green) but as long I unplug and plug, all is fine and I can keep using TV?



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    Thread moved to correct section.

    How old is the TV?

    Quite likely dry solder joints, poor connections and/or faulty caps.

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    Quote Originally Posted by mtv View Post
    Thread moved to correct section.

    How old is the TV?

    Quite likely dry solder joints, poor connections and/or faulty caps.
    Thanks for moving my thread to right topic.

    TV must be over 10years old I assume, GE6804. Never had a single problem till now.

    Yes, I thought about something loose, poor connection.
    But green screen is not consistent, on/off. If poor connection then once green screen is on then it should stay green. But unplug then re-plug seem to re-set something and back to multi color pictures.

    Unlikely LCD screen, so maybe chip going bad?

    These intermittent electronics problems are always tricky to solve.
    I am posting here cus maybe other people had same or similar problems with LCD TV, not just Dick Smith but any brand LCD TV.

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    Iirc that's a rebranded AWA mhdv3720 ~ if that's correct, electrolytic capacitors on display driver board/power supply are the most likely candidates

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    DSE branded TVs of this vintage are all based on a common platform, which if I member correctly was based on a ST chipset.
    The random changing of colour points to the LVDS cable. These interlinks are notorious for intermittent picture break-up.
    In order to transfer high volumes of picture data to an LCD panel a serial interface is used for the RGB and synchronisation.
    By necessity the cable is as short as possible (to ameliorate EM radiation) and the wires are very thin. Often a "break and remake" of the plug and socket will resolve the issue.
    Interesting fact is that the LVDS data uses spread spectrum techniques to avoid radiating at the fundamental frequency.
    Often the frequency shift can be adjusted in software to comply with regulatory requirement of different countries.
    Good luck
    "The saddest aspect of life right now is that science gathers knowledge faster than society gathers wisdom." - Issac Asimov

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    Quote Originally Posted by wotnot View Post
    Iirc that's a rebranded AWA mhdv3720 ~ if that's correct, electrolytic capacitors on display driver board/power supply are the most likely candidates
    You are correct, AWA mhdv3720 is same as my GE6804, Funny I finally read the manual(AWA mhdv3720) and found some interesting features, thx

    ok, electrolytic capacitors (??) I assume you mean electrolytic capacitors is causing intermittent green screen.
    Just for my curiosity, How/why does unplug/re-plug power cord "re-set" and normal picture returns?
    Is this sign of my TV going bad? I could get permanent green screen any day? ( I ask cus I am thinking about buying a new TV considering unlikely event that electrolytic capacitors alone can not be replaced.)

    or it sounds like I might consider replacing entire display driver board/power supply now(assuming I can find the part still cus my TV is old)?

    Finally, on practical side, should I buy new TV now and move on instead of trying to repair/replace display driver board/power supply?

    BTW something I forgot to mention when green screen is activated that might be related to electrolytic capacitors.
    Most of the time there's a definite click or pop sound then green screen, then no more sound.
    But once after green screen, I can hear a constant humming or rattling noise. only happened once, all other times no noise at all.
    But whatever is causing green screen, after unplug then re-plug power cord, multi color returns, back to normal.
    Last edited by jimjoe123; 02-02-20 at 12:09 PM.

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    Quote Originally Posted by TVguy View Post
    DSE branded TVs of this vintage are all based on a common platform, which if I member correctly was based on a ST chipset.
    The random changing of colour points to the LVDS cable. These interlinks are notorious for intermittent picture break-up.
    In order to transfer high volumes of picture data to an LCD panel a serial interface is used for the RGB and synchronisation.
    By necessity the cable is as short as possible (to ameliorate EM radiation) and the wires are very thin. Often a "break and remake" of the plug and socket will resolve the issue.
    Interesting fact is that the LVDS data uses spread spectrum techniques to avoid radiating at the fundamental frequency.
    Often the frequency shift can be adjusted in software to comply with regulatory requirement of different countries.
    Good luck
    So LVDS cable ??
    I assume "Often a "break and remake" of the plug and socket will resolve the issue." means just replace LVDS cable now?
    Is it common part? Universal part or unique to my TV brand only?
    Is replacing LVDS cable something any tv technician can do?

    Lastly, can I just live with intermittent green screen? I will just unplug/re-plug power cord each time.
    or soon green screen will stay on permanently?

    I just found some more information about LVDS cable on Google. Apparently there are several LVDS cable options?
    So my tv, GE6804, where is LVDS cable? is there only one LVDS cable? or multiple LVDS cables?
    What is LVDS cable connected to? Where can I find it in back panel of tv?
    Last edited by jimjoe123; 02-02-20 at 12:15 PM.

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    Quote Originally Posted by jimjoe123 View Post
    Finally, on practical side, should I buy new TV now and move on instead of trying to repair/replace display driver board/power supply?

    BTW something I forgot to mention when green screen is activated that might be related to electrolytic capacitors.
    Most of the time there's a definite click or pop sound then green screen, then no more sound.
    But once after green screen, I can hear a constant humming or rattling noise. only happened once, all other times no noise at all.
    But whatever is causing green screen, after unplug then re-plug power cord, multi color returns, back to normal.
    First up, I would advise you not run the set in this state -- by the sound of that last para there, bad capacitors are very likely, and continuing to run them (with their ESR out of spec) will invariably stress the mosfets. (if that happens, repair cost can escalate)

    I'm not sure if it's economically viable to replace board assemblies (presuming one could still source same, it is an old set). If merely re-capping the relative boards is a fix, then it's worth the repair (especially if you can do this yourself or know someone with the relevant skills). Due to the set age, if the repair was going to be greater than $100 or so, it'd make more sense imho to save that money & buy a new unit (and perhaps sell the old unit on ebay as parts only/not working)

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    Can I just remind you that electronics out of spec can have a minor or a major effect on its performance usually the later after time ,The reason it keeps going on/off is pure luck so dont push it It wont fix its self dont use it is my advise untill its repaired . but you can take the advise or not sooner or later the smoke WILL escape

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    ok, thanks to all who replied. I learned a lot. What a GREAT forum.
    So I will inquire about capacitor, or board replacement soon.
    I am in Philippines so display driver board/power supply replacement is unlikely UNLESS I can find Dick Smith tv junk yard, LOL

    Back to capacitor, Is it just one particular capacitor on display driver board/power supply?

    Of course last option is wait till permanent green screen then just buy a new tv. There are good China made LCD tvs.

    BTW I was told that Dick Smith tvs are marginal quality but I had this tv over 10 years and been GREAT for me.
    Too bad Dick Smith is out of business now.

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    I couldn't tell you which capacitor(s) are the actual culprit ; normally speaking the manufacturers cut costs and buy cheap capacitors for the whole unit ; replace one, replace all...if they're all the same brand, they're all not far from failing if one has already failed (depends on where they're used in circuit). I would imagine there's less than $20 worth of capacitors involved to recap the boards ...you can get an idea of what's involved by watching this random youtube video I found... ...and the powersupply/inverter board is usually the first place to start.

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    I'd just be buying a new TV now..... big improvements in 10 years.

    Then if you bother to fix the old one, you'll have a spare, or a second TV for another room.

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    Quote Originally Posted by mtv View Post
    I'd just be buying a new TV now..... big improvements in 10 years.
    Agreed.... After a recent walk through "The Good Guys", i got recalibrated how cheap new TVs are
    Sony 4K OLED Smart TV 55" TV's (Android) for $800.
    Last edited by ol' boy; 03-02-20 at 08:35 PM.
    If u want to go on an expedition get a Land Rover, if u want to come home from an expedition get a Landcruiser!

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    Additional information.....
    Before it was always green, but now pink and purple at random.

    At first (few months ago when problem started), after "click" then green screen, no noise inside tv. But now almost always there's a noise inside tv panel. Like "whistling" or "static sound" from bad speakers (not from tv speaker, only a description of noise that I hear).

    Before I needed to unplug from outlet (complete separation) then re-plug. But now pressing power button button under tv will get tv back to normal. I thought "hard reset" was only from unplugging. I am not sure power button under tv is "hard reset"?

    I asked several lcd tv repair shops. NOBODY ever heard of my problem muchless know how to fix it. (BTW I can't take to repair shop cus when I plug in at shop everything works perfect)
    Of course I googled it all, NOTHING.
    Such a mystery. Now I am just curious. Afterall LCD tv are simple machines.

    Also I wanted to take off back cover so I can see what's happening (noise) when green/pink screen problems. This tv has circuit boards stuck to back cover and linked by cable to LCD. So I can't watch tv with back cover opened.
    Last edited by jimjoe123; 06-02-20 at 12:39 PM.

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    I took of back cover, checked all capacitors, none bulged, all flat, so I assume not capacitor problem.

    The initial "click" or "cluck" sound when green/pink problem starts, sounds like some kind of magnetic click or circuit breaker tripping, Maybe overload? heat?

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    Power supply board by the sounds of that, re-cap it ; bad cap may not be visually obvious. Somewhat coincidentally I've got a philips 24" LCD monitor power/inverter board on my bench now for a re-cap -- it's fitted with TAICON branded capacitors, they visually look absolutely fine, but when you turn the unit on it's good for roughly 5minutes, then the backlight starts to faintly flicker, screen colours goes nuts...and it shuts down. I've since pulled the caps and measured ESR and I'm seeing many 10s of ohms across the lot of them. (the actual culprit had an ESR of 90 @ room temp). TAICON caps are usually pretty good but they don't seem to enjoy cramped hot working environments too well, and most units are in the 7-10year old usage window so meh, not too bad for a budget line of Nichicon caps one supposes

    Did you happen to note the brand of capacitor used?

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    Quote Originally Posted by wotnot View Post
    Power supply board by the sounds of that, re-cap it ; bad cap may not be visually obvious. Somewhat coincidentally I've got a philips 24" LCD monitor power/inverter board on my bench now for a re-cap -- it's fitted with TAICON branded capacitors, they visually look absolutely fine, but when you turn the unit on it's good for roughly 5minutes, then the backlight starts to faintly flicker, screen colours goes nuts...and it shuts down. I've since pulled the caps and measured ESR and I'm seeing many 10s of ohms across the lot of them. (the actual culprit had an ESR of 90 @ room temp). TAICON caps are usually pretty good but they don't seem to enjoy cramped hot working environments too well, and most units are in the 7-10year old usage window so meh, not too bad for a budget line of Nichicon caps one supposes

    Did you happen to note the brand of capacitor used?
    NO, I didn't check capacitor brand. Next time I open back cover I will look.

    ok. let's say power supply board is the problem. What parts on board make that "click" sound? Capacitor popping? I didn't see any magnetic or coil windings, mostly chips. Nothing moving parts.

    Also, what's so puzzling with my problem is that I can always reset by unplugging cord from outlet then re-plug in, OR press power button under tv OFF then ON while still plugged into outlet. (I thought "hard reset" is done from complete electrical separation from outlet??)
    So somehow I created "reset" situation where normal colors returned.

    I thought maybe HEAT problems, but problem is not consistent, sometimes over a day no green/pink, then few time 2-3 green/pink in few hrs.

    If my problem just stay put either green or pink screen, then it's easier to troubleshoot. but it doesn't.

    Now I am more curious, mystery to be solved?? LOL. I bought another LCD tv, but if this problem is simple to repair then why not fix it?

    Maybe after all the discussions, tv will work always as long as I OFF/ON power button or unplug/re-plug, like a hard reset(??)

    BTW I noticed when green/pink screen happens, side menu buttons (vol, ch, etc...) don;t work.

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    Quote Originally Posted by wotnot View Post
    but when you turn the unit on it's good for roughly 5minutes, then the backlight starts to faintly flicker, screen colours goes nuts...and it shuts down.
    What is so unique and frustrating about my problem (unlike what you described) is I can reset by unplug/re-plug power cord or OFF/ON power button, then I am back to normal.

    But your case it's OFF, TURNED OFF, DONE, SHUT DOWN, etc....so easier to troubleshoot. Capacitors bad, so OFF, then you replace capacitors then ON again, Clear definite OFF or ON, or working or not working.

    My case starts with "click" or "thump" sound but back to normal later.

    I wish I can take off back cover and expose boards, so when I hear noise I can try to isolate the problem. But I can not take separate back cover and LCd panel cus cable connections.

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    Well the philips goes again ; I know the fault set differs from your's, I was merely pointing out visual inspection of capacitors is by no means a 'pass' =)

    It's been many years since I worked in teevee repair, but you just reminded me of this set's layout -- they've got the power and receiver boards on the back cover, and the t-con and inverter boards on the main chassis with the display..yes?

    Whistling or clicking/cracking sounds may actually be the inverter board in this case (I was thinking of another chassis), and the fault history/progression you describe is one of the situation degrading, and this is typical of capacitor failure modes.

    Due to the fact it seems rather sporadic at the same time, I could probably see myself pulling all boards out and doing a visual inspection for cold/cracked solder joints and the like... but whistling/whining and/or static sounds suggest a hivoltage circuit, and the inverter board would be a good candidate (the set I was thinking about had power & inverter section on the one board =).

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    Quote Originally Posted by wotnot View Post
    Well the philips goes again ; I know the fault set differs from your's, I was merely pointing out visual inspection of capacitors is by no means a 'pass' =)

    It's been many years since I worked in teevee repair, but you just reminded me of this set's layout -- they've got the power and receiver boards on the back cover, and the t-con and inverter boards on the main chassis with the display..yes?

    Whistling or clicking/cracking sounds may actually be the inverter board in this case (I was thinking of another chassis), and the fault history/progression you describe is one of the situation degrading, and this is typical of capacitor failure modes.

    Due to the fact it seems rather sporadic at the same time, I could probably see myself pulling all boards out and doing a visual inspection for cold/cracked solder joints and the like... but whistling/whining and/or static sounds suggest a hivoltage circuit, and the inverter board would be a good candidate (the set I was thinking about had power & inverter section on the one board =).
    Thanks for your reply. I will have a repair guy check out inverter, capacitors, etc....
    Yes, I agree, from the noises I would think something to do with power problem.

    Can you shed light on this question?
    Why is it intermittent? If something is bad, pops, cracks, then why does it come back to normal simply by unplug then re-plug?
    Why not just stay bad? Not able to return to normal?
    Curious why something in power supply chain temporary goes bad then good again after power OFF then ON?
    It's like chasing a ghost...Mystery???
    With so many LCD screens in operation, why is my problem so unique? Green/pink screen issues are very common, I would assume.

    All the research I done so far shows if there's problem (green/pink screen) then it stay that way till fixed.
    Like I said, maybe from now on just live with it, simply unplug then re-plug in or press power button OFF then ON.

    Anyway thanks for you input.

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