MrGnome
New Member
Hi!
A while ago the voltages from my TV-out (Composite) on my ATI Radeon 9800 card dropped, with the result being a very dark and grey picture. Tops measured with a scope are about 250mV with white output, and they should be about 1000mV. This happened after connecting to the TV while the TV was on. The circuit on the card has both composite and S-vhs output on a 7-pin "enhanced" s-vhs socket. (the extra pins are for the composite signal)
First the composite signal went dark, but the s-vhs signal was ok, so i got a cheap converter cable that worked quite ok for a while, until i forgot to turn off the TV when i connected the cable one night, and the same thing happened to the svhs circuit. The luminance range was "squashed"
I don't have schematics for the TV-out circuitry on the card, but the contrast and saturation settings in my driver works a little bit, so the circuits handling the changes seem ok.
I don't know how these composite converter circuits work, but i guess some component has died, "zapped" by a strange grounding problem or similar on the tv.
Perhaps it would be possible to change a failing component on the card, if i just know which one it is.
(Attached is the signal viewed in PICO Scope, showing the levels. signal source is a white screen)
Please, if you have any information, give me a hint or two
A while ago the voltages from my TV-out (Composite) on my ATI Radeon 9800 card dropped, with the result being a very dark and grey picture. Tops measured with a scope are about 250mV with white output, and they should be about 1000mV. This happened after connecting to the TV while the TV was on. The circuit on the card has both composite and S-vhs output on a 7-pin "enhanced" s-vhs socket. (the extra pins are for the composite signal)
First the composite signal went dark, but the s-vhs signal was ok, so i got a cheap converter cable that worked quite ok for a while, until i forgot to turn off the TV when i connected the cable one night, and the same thing happened to the svhs circuit. The luminance range was "squashed"
I don't have schematics for the TV-out circuitry on the card, but the contrast and saturation settings in my driver works a little bit, so the circuits handling the changes seem ok.
I don't know how these composite converter circuits work, but i guess some component has died, "zapped" by a strange grounding problem or similar on the tv.
Perhaps it would be possible to change a failing component on the card, if i just know which one it is.
(Attached is the signal viewed in PICO Scope, showing the levels. signal source is a white screen)
Please, if you have any information, give me a hint or two