Apple IIGS display problem

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Apple IIGS display problem

Hello there,

I have an Apple IIGS connected to a lcd tv via the scart (peritel) socket.

With other computers (for example Apple IIe + Chat Mauve or CPC6128) this socket is ok.

I get the the subd15 to scart cable from England on Ebay.

The problem is that sometime the tv loose the vertical sync.

The display is stable and perfectly looking for some seconds and then he start to slowly move vertically then stabilize again and so on....

I carefully check and move the cable searching bad contact but everything look good.

On your opinion should I try another tv or is the problem inside the IIGS ?

Thanks and regards.Philippe

 

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Joined: Feb 27 2021 - 18:59
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NTSC

I believe the other computers you mentioned use a 576i video output at 50 Hz (PAL), whereas the IIgs only provides 480i at 60 Hz (NTSC). This is also true when RGB signals are used.

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NTSC

Could this explain what I see ?

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Fixed

You put me on the way !

 

Switching the frequency setting of the IIGS from 50 Hz to 60 solve the problem.

Now the display is stable.

Strange that I have to use a US (NTSC) setting for a EU Philips tv ??? 

Thanks.

Philippe

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A lot of those Phillips TVs

A lot of those Phillips TVs actually support both NTSC and PAL.  I had friends who were stationed in Germany who brought home Phillips TVs that were able to be used here.  I suspect they were mostly purchased on base, so maybe not always models widely available on the general market.  Possibly they were intentionally built for PX customers because they knew that at some point it was likely they'd be going back home.

 

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