Casio TV-570 Viewing Angle Problem

[PortableTV]

I picked up this cute little TV with a bummer of a problem...

When I adjust the "Bright" pot I cannot get any clear image when viewed straight on. I can only see a clear image when looking down at the screen from a steep angle above.

Is this a failure of the crystals in the LCD? A problem with the pot circuit? Is there some polarizing film on top of the LCD that perhaps was installed wrong?

[JohnCT]

It almost sounds like someone took this apart and got the polarizer sheets installed wrong in front of the LCD module.

It could also be a circuit problem. Most electronics in those days used "fish" caps: small surface mount electrolytics that go bad. We used to change several hundred a week when we did camcorders.

If the TV seems to improve with run time, that could be it. Also, putting it in a warm spot (like near a radiator) and warming it 20 deg above room temp may also improve it. Most thermal issues are cap related.

EDIT: is there also a "contrast" control in addition to the bright? Viewing angle changes dramatically with contrast and brightness with LCD screens even when working as designed.

John

[PortableTV]

Originally Posted by JohnCT

It almost sounds like someone took this apart and got the polarizer sheets installed wrong in front of the LCD module.

It could also be a circuit problem. Most electronics in those days used "fish" caps: small surface mount electrolytics that go bad. We used to change several hundred a week when we did camcorders.

If the TV seems to improve with run time, that could be it. Also, putting it in a warm spot (like near a radiator) and warming it 20 deg above room temp may also improve it. Most thermal issues are cap related.

EDIT: is there also a "contrast" control in addition to the bright? Viewing angle changes dramatically with contrast and brightness with LCD screens even when working as designed.

John

I opened it up - what a nightmare

I found a blown cap on the back of the LCD PCB. I jiggled it with a toothpick and the image cleared up straight-on. Off to Mouser for new caps.

John, there is no contrast control on this TV. It just has "bright" and then a red/green "tint" knob on the bottom.

The image is surprisingly poor and low resolution. I believe this TV was made in 1990 but the screen quality looks like something from 1986.

Another question John - Do you take on repairs for these mini Casio's? I'm burning out

[JohnCT]

I used to do them back when they were expensive, but like camcorders, VCRs, CDs, DVDs, etc, I stopped taking them in (my living, not a hobby).

The picture you're seeing when the capacitor is jiggled is probably normal and the best you'll get. Even when new, they "worked", but not well. The crappy image was overlooked because it was truly a pocket TV and produced a color picture of sorts. The resolutution is poor because the pixel density is low. Take a look at the screen under an eye loupe and you'll see what I mean.

John

[jhalphen]

Hi to all,
@Portable TV : on Frank Guenthoer's web site you can watch the evolution of micro-TV screen resolutions via a series of photographs.
Covers B&W and Color sets; CRT and LCD :

http://www.guenthoer.de/testbild.htm

Main site, in German :
http://www.guenthoer.de/

Click on English summary at the bottom of the page, the main pages are translated.

Best Regards
jhalphen
Paris/France