Damaging computer monitor with wrong input?
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Posted by no-spam2@lycos.com on February 17, 2007, 2:05 pm
Please log in for more thread options I'm working on an output circuit from a computer which outputs two different kind of signals according to which mode it is set to (colour low/medium resolution or monochrome high-resolution): Mono mode : 35.70 KHz horizontal, 71.2 Hz vertical Colour mode: 15.75 KHz horizontal, 50-60 Hz vertical Is it possible to damage a monitor if it receives signals outside of its intended range? | |||||||||||||||||||
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Posted by Gibbo on February 17, 2007, 2:10 pm
Please log in for more thread options no-spam2@lycos.com wrote: I think I am right in saying that older monitors would sometimes fail (often with a bang) if fed an input with too high a line frequency. Later monitors simply either ignore it or shutdown. So it depends on your monitor. -- Gibbo This email address isn't real. | |||||||||||||||||||
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Posted by no-spam2@lycos.com on February 17, 2007, 5:31 pm
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> no-sp...@lycos.com wrote:
> > Mono mode : 35.70 KHz horizontal, 71.2 Hz vertical
> > Colour mode: 15.75 KHz horizontal, 50-60 Hz vertical >
> > Is it possible to damage a monitor if it receives signals outside of
> > its intended range? >
> I think I am right in saying that older monitors would sometimes fail > (often with a bang) if fed an input with too high a line frequency. > Later monitors simply either ignore it or shutdown. > > So it depends on your monitor. That's good and bad news. The computer is an Atari ST and I intend to make it work with both the custom Atari monitors and normal VGA monitors. Sounds like it could be risky business to connect the Atari monitors (the Atari ST is a mid 80s - early 90s computer) to the new output without first making sure the mode is correct for that monitor. When you say they often go out with a bang -is that permanent failure (as in throw it away, the CRT and everything is gone), or is it "just" a matter of replacing some components around the signal input stage? Anything that can be done to prevent this (in case I or someone selects the wrong mode for the connected monitor)? Regarding modern monitors I've heard that it's hard to find ones that can handle the colour mode of 15.75 KHz horizontal rate -is this true, or is it now common for monitors to be able to handle both my output modes? | |||||||||||||||||||
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Posted by Michael A. Terrell on February 17, 2007, 6:17 pm
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"no-spam2@lycos.com" wrote: >
> That's good and bad news. > The computer is an Atari ST and I intend to make it work with both the > custom Atari monitors and normal VGA monitors. Sounds like it could be > risky business to connect the Atari monitors (the Atari ST is a mid > 80s - early 90s computer) to the new output without first making sure > the mode is correct for that monitor. > When you say they often go out with a bang -is that permanent failure > (as in throw it away, the CRT and everything is gone), or is it "just" > a matter of replacing some components around the signal input stage? > Anything that can be done to prevent this (in case I or someone > selects the wrong mode for the connected monitor)? > > Regarding modern monitors I've heard that it's hard to find ones that > can handle the colour mode of 15.75 KHz horizontal rate -is this true, > or is it now common for monitors to be able to handle both my output > modes? The flyback transformers went up in flames. The original monochrome monitor for the IBM PC would burn if it was powered up without video drive. That is why the power supply had the switched outlet than lasted till the ATX format arrived. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida | |||||||||||||||||||
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Posted by Gibbo on February 17, 2007, 6:21 pm
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no-spam2@lycos.com wrote: >> no-sp...@lycos.com wrote:
>
>>> Mono mode : 35.70 KHz horizontal, 71.2 Hz vertical
>>> Colour mode: 15.75 KHz horizontal, 50-60 Hz vertical >>> Is it possible to damage a monitor if it receives signals outside of >>> its intended range? >> I think I am right in saying that older monitors would sometimes fail
>> (often with a bang) if fed an input with too high a line frequency. >> Later monitors simply either ignore it or shutdown. >> >> So it depends on your monitor. >
> That's good and bad news. > The computer is an Atari ST and I intend to make it work with both the > custom Atari monitors and normal VGA monitors. Sounds like it could be > risky business to connect the Atari monitors (the Atari ST is a mid > 80s - early 90s computer) to the new output without first making sure > the mode is correct for that monitor. > When you say they often go out with a bang -is that permanent failure > (as in throw it away, the CRT and everything is gone), or is it "just" > a matter of replacing some components around the signal input stage? Usually trivial things like the output transistor and associated components :) Repairable...... if you know what you're doing, but not trivial. > Anything that can be done to prevent this (in case I or someone
> selects the wrong mode for the connected monitor)? > I'm not sure about this but I don't think you can swap modes on the ST without switching it off and back on again. At boot up it looks at the 13 pin socket to see if it has the "special" monitor attatched, if it does, then it fires up in hi res mode. > Regarding modern monitors I've heard that it's hard to find ones that
> can handle the colour mode of 15.75 KHz horizontal rate -is this true, > or is it now common for monitors to be able to handle both my output > modes? > The standard colour output of the Atari ST is bog standard European TV line frequency. There were *millions* of monitors made with the same standard that are now worth about nothing each. Car boot sales are full of them. It will work into a scart input on a normal UK TV -- Gibbo This email address isn't real. | |||||||||||||||||||
> different kind of signals according to which mode it is set to (colour
> low/medium resolution or monochrome high-resolution):
>
> Mono mode : 35.70 KHz horizontal, 71.2 Hz vertical
> Colour mode: 15.75 KHz horizontal, 50-60 Hz vertical
>
> Is it possible to damage a monitor if it receives signals outside of
> its intended range?
>