For the TV experts

[Ian Robinson]

My old NEC 68cm Flatscreen TV has started getting the "blue screen" intermittentaly (and it's no longer all blue but has violet fringing on the upper and lower left hand corners that extend about 1/4 way to middle.

When the picture was getting lost momentarily , initially I thought the problem was withthe signal but I have also noticed the colours are off when the picture is "fine" .

Short term - I have selected 9/16 aspect from the set top box and the DVDR VCR combo and that reduces the effect , but I know it's there so I can still see it.

Am correct in assuming the tube is on it's way out ??? ... got a vague recallection that this is what I saw on the old Sanyo 54cm before the picture tube died all together.

Worth getting a TV service guy fix it ?
or should I just wait for the tube to pack in it because it's likely to be a pricey job fixing the problem ?

I don't want to replace the TV just yet (unless I have no choice), am waiting on HD 1080 plasmas and LCDs to become less power hungry, their technology to become more reliable and , of cause for the price to fall a bit more.

[mithrandir]

Probably.

Almost certainly not worth the cost.

The age old problem with technology. You can have it today and pay more or buy it later when it's cheaper. For instance:
A 30" LCD plus a 22" LCD cost about half what my 42" plasma cost when I bought it. They are all HD but not 1080p.
My first HD decoder was ~$700. The second one ~$200. The two LCDs have HD decoders built in.

None of those, nor the three LCDs on the computers, have failed. There are no CRTs left in the house.

Andrew

[supernova1965]

We have had this problem when we had moved our set and it needed degaussing you can get tools to do it or you can disconnect all power for at least 30 min we used to get pink colour through the blue its something to do with magnetism.

[Ian Robinson]

That rings a bell .... I'll try tuning it off all together by pulling the plug out of the power board and see if that helps ....

Our TV has never been moved , is too big and heavy to move about , so I am wondering if a recent electrical storm (was very violent electrically) may have surged it (I know powerboards are ineffective in stopping surges from nearby lightning strikes).

Of cause I also rrsk it dying completely when I try a "cold boot".

[mithrandir]

Does it have a degauss control? Some if not all sets do, especially the larger models.

I'm not an electronic technician, but had some experience with degaussing before ditching the last CRT.

Don't get overenthusiastic with it. It generates high pulse currents (the BOING noise should be a clue) and you don't want to overheat the circuitry. Leave the set several minutes to cool and stabilise. If it is better but not good enough, another degauss might improve it, but the laws of diminishing returns apply.

[Satchmo]

FULL HD 32" a currently pretty cheap ie :
http://www.kogan.com.au/shop/kogan-1080p-32-full-hd-lcd-tv-hd-tuner/

( Not a spam : just an example of how costs have come down..)

[Kevnool]

I had a 80cm giant but i just gave the thing away as it was just to big.
Then i replaced it with a 120 cm (if that is the size) power hungry and you dont need a heater in winter with the heat that comes out of it.
And now it sits in a corner not being used since i use a projector for all tv and sons gaming.

So get rid of the bulky thing and save time / headaches / money /space.

Cheers Kev.

[mswhin63]

All tube TV's have degaussing cct's wired to the on/off switch. If you use the standby all the time the magnetism has grown over time and it is usually harder to remove immediately. So a few on/off's from the switch maybe needed. The degaussing cct's is simple and relies on a thermister (temperature controlled resistor) to switch the degaussing off once it has warmed up. Hence the reason for switching off for long periods.

Blue screen is usually loss of signal from the antenna or set top box. It sees the video sync pulses to determine a signal so the blue screen can occur on the tuner and the AV inputs.

[Ian Robinson]

Unplugging for an hour seems to have made the problem go away (for now) .... ie no fringing now + the unconnected DVD and Video2 RCA connection blue screens are all pure blue as they should be.... :thumbsup:

I can put off buying a new TV for now .... was looking seriously at buying a Samsung 42" full HD plasma or Samsung 37" full HD LCD (both about $1100, I'm sure if I offer cash , I can beat that price down to under $1000) . Would rather keep my $1100 for now.
Anything bigger will be way too expensive , overkill , too big for our lounge-room and would involve needing a new TV / Video cabinet/stand as well = even more expense !!! I don't want to have move my wall cabinet or have to get a new video cabinet as well , nor do I want to stuff about wall mounting a big plasma or LCD TV.

Edit : the signal (via the VCR and set top box still disappears occasionally .... get blue screen and sound only intermittently .... bummer ....
The DVDR C+VCR and set top box are new (less than 2 months old) so I think there is still an issue with the old TV .... will try connecting the RCA feeder from the DVDR C+VCR and set top box to VCR2 and see if this stops the problem .... crossing my fingers.

[Starkler]

Definitely not.
Consult ebay for current market values of large CRT televisions. I have a 68cm crt in excellent condition I cant give away.

[matt]

I sold my 68cm JVC (flat screen) crt to a member of IIS...no probs.

[Ian Robinson]

Yep my mum just upgraded to a big plasma full HD TV and she now has her old 68cm Panasonic TV in the bedroom ....

She offered me her old 68cm , but mine is newer and has a flat screen , at the time I declined and suggested she offer it to one of my sisters (she's got an older TV that is just about had it , and less money than us) therefore she needed it more .... had I only known .... too late now.

If mine dies or becomes unwatchable (the loss of picture becomes too frequent and longer than a second or 2) , I can always put the old NEC 48cm back into service until I am ready to bite the bullet and upgrade.

[danielsun]

My older 68cm tube tv got the color fringing in the top LH cnr and got worse each week until I got some advice to unplug it from the wall and leave it over night and it fixed the problem permanently until it blew up about 5 years later.
As for the blacking out I have bought a new 42 inch LCD which blacks out now and then for a second or two and was told I need a new digital antena which I did but it still blacks out. LG seem to think it's not their problem.:shrug:

Cheers Daniel.

[GeoffW1]

Tandy/DSE have a couple of reasonable prices just now, eg a Sanyo 32" for $599 (not full HD though, just-barely HD, 1366x768).

Edit: Not spam either, honest, I have no connection with them, matter-of-fact I hate them.

Cheers

[Barrykgerdes]

Hi
I think the fault has been pretty well covered. The old shadow mask CRT picture tubes had a very high precision etched (I think) mask to direct the three beams onto the correct phosphors.

This mask picks up a residual magnetic field from the earth's magnetic field after it has been left in one position for any length of time. If the set is moved the new field causes a slight deflection of the beams so that they don't quite impinge on the correct phosphors.

The correction for this is a multi-turn "deflection yoke" placed at the shadow mask. Each time the set is turned on a "pulse" of high intensity AC is connected to this yoke to "degauss" the mask. However if the set has been moved after a long period in one position it may take four or five re-starts to fix the problem. This degaussig or re-magnetising from the earth's magnetic field can also occur naturally if the set is left standing in its new site for three or four days.

Another point about the older shadow mask CRT's is colour rendition. The emition phoshors emit a much truer colour than the filter type LCD's. I don't know the parameters of the plasma.

Barry