Invalid format on VGA output from Amiga's

-Acid- · 08 April 2018, 23:06

Can anyone tell me why the VGA output from my IndiAGA Mk1 on an A1200 and CV64/3D from an A4000 will not display on anything other than a pc monitor?

I tried it directly to a TV on the VGA port but it says the signal is invalid. I also tried a VGA to Component cable and it also says the signal is invalid. I bought a VGA to HDMI adapter and again the signal is invalid. The TV and adapter both work fine with a PC VGA output. I've also tried connecting it to a Hauppauge PVR with the same results.

I was considering buying one of these VGA to HDMI adapters or even a small TV with a VGA connector to use as a monitor but now I am not so sure anything will work with it.

How can I capture the VGA output from either of these devices?

ajk · 09 April 2018, 08:31

Both the Indivision and Cybervision are quite widely configurable. Is the output something that is definitely standard, such as 640x480 or 800x600 at 60Hz? What do those other devices report it as?

-Acid- · 09 April 2018, 09:50

I'm trying a standard pal wb hi-res screen on both.

ajk · 09 April 2018, 10:14

Yes, that's the screen mode on the Amiga side, but what is the output configured as? It might be 50Hz, or perhaps some exotic resolution which is why many VGA devices will reject it.

E-Penguin · 09 April 2018, 11:17

I certainly find newer monitors to be less forgiving with non-standard VGA modes.

demolition · 09 April 2018, 13:14

The output from those scandoublers are not within VGA specs so it is a bit of a gamble whether it will work or not. While monitors may be forgiving, modern TVs are often quite picky and will only work with 100% plain VGA signals, e.g. exactly 60/75Hz and only 640x480, 800x600, 1024x768 etc. I only have the Indivision ECS but I think it is quite similar to the AGA MkI, and in PAL modes it will either output 50 Hz or 62.5Hz. While 62.5 Hz is somewhat close to 60 Hz, it is still not 60 Hz which is the standard VGA refresh rate.
Try if it works better with NTSC modes since that will produce a 60 or 75 Hz signal from the Indivision.

08 April 2018, 23:06	#1
-Acid- Registered User Join Date: Oct 2012 Location: South Shields Posts: 812	Invalid format on VGA output from Amiga's Can anyone tell me why the VGA output from my IndiAGA Mk1 on an A1200 and CV64/3D from an A4000 will not display on anything other than a pc monitor? I tried it directly to a TV on the VGA port but it says the signal is invalid. I also tried a VGA to Component cable and it also says the signal is invalid. I bought a VGA to HDMI adapter and again the signal is invalid. The TV and adapter both work fine with a PC VGA output. I've also tried connecting it to a Hauppauge PVR with the same results. I was considering buying one of these VGA to HDMI adapters or even a small TV with a VGA connector to use as a monitor but now I am not so sure anything will work with it. How can I capture the VGA output from either of these devices?

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09 April 2018, 08:31	#2
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	Both the Indivision and Cybervision are quite widely configurable. Is the output something that is definitely standard, such as 640x480 or 800x600 at 60Hz? What do those other devices report it as?

09 April 2018, 09:50	#3
-Acid- Registered User Join Date: Oct 2012 Location: South Shields Posts: 812	I'm trying a standard pal wb hi-res screen on both.

09 April 2018, 10:14	#4
ajk Registered User Join Date: May 2010 Location: Helsinki, Finland Posts: 1,341	Yes, that's the screen mode on the Amiga side, but what is the output configured as? It might be 50Hz, or perhaps some exotic resolution which is why many VGA devices will reject it.

09 April 2018, 11:17	#5
E-Penguin Banana Join Date: Jul 2016 Location: Darmstadt Posts: 1,213	I certainly find newer monitors to be less forgiving with non-standard VGA modes.

09 April 2018, 13:14	#6
demolition Unregistered User Join Date: Sep 2012 Location: Copenhagen / DK Age: 43 Posts: 4,190	The output from those scandoublers are not within VGA specs so it is a bit of a gamble whether it will work or not. While monitors may be forgiving, modern TVs are often quite picky and will only work with 100% plain VGA signals, e.g. exactly 60/75Hz and only 640x480, 800x600, 1024x768 etc. I only have the Indivision ECS but I think it is quite similar to the AGA MkI, and in PAL modes it will either output 50 Hz or 62.5Hz. While 62.5 Hz is somewhat close to 60 Hz, it is still not 60 Hz which is the standard VGA refresh rate. Try if it works better with NTSC modes since that will produce a 60 or 75 Hz signal from the Indivision.

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