Fixing Monitors and TV Sets

[audioguru]

Hi Nigel,
Scanning lines are horizontal and are from the top to the bottom. Resolution "lines" are vertical and go left to right. They have nothing to do with each other.

You can have many more resolution lines than scanning lines but more scanning lines are better because then they become invisible.

1920 pixels resolution is 920 black vertical lines with another 920 white vertical lines in between.

This site explains it: HDTV-Resolution and TV Picture Quality

 

[Nigel Goodwin]

I've still no idea what you're on about with 920? (or 960) - a Full HD set is 1920 pixels wide, by 1080 pixels high - it's not a scanned display as such (which is why you can photograph it, unlike a CRT), and there are no lines (either vertically or horizontally).

Of the 1920 pixels across the width, each 'pixel' is made of three pixels, one red, one green, and one blue - but that's pretty irrelevent really - it's 1920 pixels across.

I see from that site, NTSC is 480 visible lines (should have remembered that, I did know it), as against 576 for PAL.

 

[audioguru]

I see from that site, NTSC is 480 visible lines.

Yes, scanning lines, not number of lines of resolution.
1) A good live show has 330 lines of resolution.
2) A DVD is said to have 480 lines of resolution on one site and 540 lines of resolution on another site.
3) A VHS tape recording has from 180 to 240 lines of resolution.

They all have 480 visible scanning lines.

Some huge sets have scanning line doublers so that you cannot see the horizontal scanning lines. But their resolution with a regular program is the same.

To test for the number of lines of resolution, have a picture displayed with vertical lines of black, white, black, white across the screen. Increase the number of these vertical lines until they visibly merge together and become a blank grey raster without any vertical lines. The resolution is where the lines can still be seen.

 

[Nigel Goodwin]

Yes, scanning lines, not number of lines of resolution.
1) A good live show has 330 lines of resolution.
2) A DVD is said to have 480 lines of resolution on one site and 540 lines of resolution on another site.
3) A VHS tape recording has from 180 to 240 lines of resolution.

They all have 480 visible scanning lines.

You're talking analogue there, and very poor quality analogue if a live show only has 330 lines resolution.

DVD is a digital format, and provides 480 lines on NTSC and 576 lines on PAL, obviously depending on the original source material.

Likewise digital TV provides resolution matching the broadcast format, again depending on original source - HD has been good for us, instead of American programming coming over as NTSC and poor resolution, much now comes over as HD and can be scaled down to a good PAL resolution.

Some huge sets have scanning line doublers so that you cannot see the horizontal scanning lines. But their resolution with a regular program is the same.

Such schemes were always rubbish way back in the 50's they tried to do similar things with 'spot wobble', that didn't work either.

The main reason for 100Hz (120Hz in the USA) is to reduce frame flicker, it's merely a side effect that it doubles the line frequency.

 

[audioguru]

You're talking analogue there, and very poor quality analogue if a live show only has 330 lines resolution.

Our channel bandwidth is (was) only 6MHz. The B/W video has a bandwidth of only 2.8MHz on cheap sets (they roll-off the highs to avoid dot-crawl from the 3.58MHz chroma) and good sets have a B/W video bandwidth of about 4.1MHz (they rolloff the highs to avoid interference from the 4.5MHz audio).
The resolution with a video bandwidth of only 2.8MHz or 4.1MHz is (was) poor.

DVD is a digital format, and provides 480 lines on NTSC and 576 lines on PAL, obviously depending on the original source material.

The auxilliary input to most regular TVs is analogue with a poor bandwidth.
Cheap sets have a resolution much worse so that a DVD, a good live show and a VHS tape look almost the same.

way back in the 50's they tried to do similar things with 'spot wobble', that didn't work either.

Nearly all regular North American TVs have "spot wobble" so that the scanning lines are not as visible.

 

[shokjok]

Sony may not be making great monitors ( even if assembled in Mexico), but they make the best home audio equipment. I have a Sony TCFX-510R cassette deck working since 1985, a PS-X600 turntable and a Betamax video player recently obtained, if I can find a Beta tape worth viewing.

 

[Nigel Goodwin]

Our channel bandwidth is (was) only 6MHz. The B/W video has a bandwidth of only 2.8MHz on cheap sets (they roll-off the highs to avoid dot-crawl from the 3.58MHz chroma) and good sets have a B/W video bandwidth of about 4.1MHz (they rolloff the highs to avoid interference from the 4.5MHz audio).
The resolution with a video bandwidth of only 2.8MHz or 4.1MHz is (was) poor.

The UK has intercarrier sound at 6MHz, with VERY high quality NICAM digital sound above that - the colour sub-carrier is 4.43361875MHz - and video bandwidth is about 5.5MHz.

Bit of a bummer, only 4.5MHz sound

The auxilliary input to most regular TVs is analogue with a poor bandwidth.
Cheap sets have a resolution much worse so that a DVD, a good live show and a VHS tape look almost the same.

UK TV's and DVD players have SCART sockets, which (mostly) include RGB - this gives massively greater quality than composite, and DVD absolutely wipes the floor with VCR's and even live analogue broadcasts.

Nearly all regular North American TVs have "spot wobble" so that the scanning lines are not as visible.

I suppose having fewer lines makes it more important?, I think it was only the old 405 sets which did it here, and only a few of those.

 

[audioguru]

I fed the analogue output of my digital TV recorder and DVD player via an S-video cable to my Sony TV for the best clarity.

I have a very cheap 14" Canadian name-brand Thailand-made CRT colour TV beside me. The scanning lines are invisible because the horizontal lines are dithered or unstable. I see dot-crawl because it doesn't have a half-decent video-chroma comb filter or notch filter circuit and its video bandwidth probably exceeds 3.58MHz (choma). I don't see interference from the 4.5MHz audio. The audio shrieks from its tiny speaker and I don't think it has de-emphasis. It cost the same as a good dinner for two in a restaurant.

 

[Nigel Goodwin]

I fed the analogue output of my digital TV recorder and DVD player via an S-video cable to my Sony TV for the best clarity.

S-Video overcomes some of the defects of NTSC/PAL, but still has absolutely pathetic colour definition - it's still a black and white picture, with little kids scribbling on top with coloured crayons

But if that's the best you've got, it's the best you can do.

I have a very cheap 14" Canadian name-brand Thailand-made CRT colour TV beside me. The scanning lines are invisible because the horizontal lines are dithered or unstable. I see dot-crawl because it doesn't have a half-decent video-chroma comb filter or notch filter circuit and its video bandwidth probably exceeds 3.58MHz (choma). I don't see interference from the 4.5MHz audio. The audio shrieks from its tiny speaker and I don't think it has de-emphasis. It cost the same as a good dinner for two in a restaurant.

You spend too much on good food!

 

[audioguru]

I paid only $59.99CAN for the cheap little TV about 1.5 years ago.
I have paid much more for a good dinner for two (with a show with Spanish singers, acoustic guitar players and dancers).

 

[Nigel Goodwin]

I always find the dancers a little chewy?

 

[audioguru]

I always find the dancers a little chewy?

Interesting. I have never eaten one.
OOps I don't want to be rude.

 

[pecello]

TECHLINE TL37LC700 LCDTV color problem, green color instead black

I got problem with black color,it is green instead of black.I got 2 another MB,changed, same error,changed the lcd driver board same thing,psu voltages ok,electrolyts ok with ESRmeter.
Anybody can HELP me!???
This model is same as VESTEL 37" (17MB15)!??
THANKS in ADVANCE

btw the psu model is 17PW15-8 ,MB is 17MB15E-3,display is LG LC370WX1
**broken link removed**

 

[Nigel Goodwin]

It's called 'solarisation', it's a common problem, and can be caused by lot's of things.

One cause is software corruption, and you cure this by updating the sets software.

Other problems are the LCD or Plasma panel itself, or poor connections.

 

[aquamon]

Hi there,

One of my monitors went out a couple weeks ago and i took it
apart and could not find anything burnt out, and without a schematic
i had no way of trouble shooting it that well. I didnt want to pay
for a schematic because the monitor is old anyway.

I had a TV set (CRT) go out too a while back (few years or so) and
took that apart and spent 25 dollars for a schematic. I found that
the high voltage transistor was bad and replaced it with a custom
connection of series 400v transistors. I got a picture with that,
so i assumed it was really the HV transistor. I checked the price,
and it turned out to be around 25 dollars too. The thing is, i was
afraid to buy a new transistor because if there were other parts bad
that caused the transistor to blow out then a new transistor would
blow after a short time anyway, and besides the TV was fairly old
anyway.

So what i ended up doing in both cases is buying a new model.
Rather than put out the money for something that might not work
that much longer anyway i decided to apply that money to a new
model and at least have something that should last a while.

Anyone else ever have this kind of experience?

I "HAD" and still have it, somewhere - gathering DUST!!!
A Sony Notebook that has been back to the factory service three times!!!

But this is really getting off-topic.

Someone once said, "electrolytic capacitors are our friends!".
Check them all out with a TV that old, especially the HOT's driver.

I told my "wife" not not buy sony products from my negative experiences.
She bought a LCD tv/radio/cd player for the kitchen after!

It isn't working EXACTLY just out of warranty time frame!
I told her, dammit (I refuse to fix it).

 

[moki]

LG Flatron 17" LCD Monitor

Does anyone have a schematic for a LG Flatron 17" LCD Monitor? The monitor is dead. I opened it up and checked out the power supply, could not find anything wrong so far. No bulging caps or blown fuse. The FET seems ok as well. Does the switched mode power supply have to have a load to work as in some other power supplies? I measure nothing on the +12v and +5v output with the power supply removed from the monitor. Can send some pics of the power supply if anyone needs to have a look.

 

[aquamon]

Does anyone have a schematic for a LG Flatron 17" LCD Monitor? The monitor is dead. I opened it up and checked out the power supply, could not find anything wrong so far. No bulging caps or blown fuse. The FET seems ok as well. Does the switched mode power supply have to have a load to work as in some other power supplies? I measure nothing on the +12v and +5v output with the power supply removed from the monitor. Can send some pics of the power supply if anyone needs to have a look.

If this doesn't require a load on the 12 & 5V rails to start up the PS, then you have you problem.

Try loading it with a small wattage 12v bulb, same thing/same time with the 5 v bulb/5 volt rail.

If it works outside then the microprocessor senses a fault.

Good luck there!
Probably as simple as a blown back-panel lamp.
Check SDA for problems.

Oh, if your micro goes back to your power supply, then I think you are in above your head.

You didn't even give a model # or anything...

 

[HarveyH42]

After about 10 years or so of watching my rear-projection with messed up red, got around to draining the cooling fluid, clearing out the coagulated crap, and refilling it. Took a while to find a place that had, and would sell me the fluid. The colors still aren't quite right, but a remarkable improvement. The green seems kind of weak, should probably have check them all, while I had it apart. Also, anything white, is really bright white. Flesh tones aren't very good, range from pastie white (need some sun) to orange/red. Africans look normal. I've messed with the onscreen adjustments quite a bit, but not much fine control. Don't remember if there were adjustments in the back, weighs to much to move by myself.

 

[moki]

LG Flatron 17" LCD Monitor

Thanks Aquamon. The model is LG Flatron 1730S.

 

[reba29113]

Mitsubishi Black Square

Hi, I have a Mitsubishi Big Screen TV Model VS-5042, that has a big black square in the middle of the screen. Can anyone tell me what the problem is and how I can get it repaired or is it even worth repairing.
Thanks