Amiga RGB to Gonbes 8200 vga in

sirlemonhead · 06 March 2017, 17:55

Hi,

I've got one of those Gonbes boards but I don't have the header connector wires that typically come with them.

I've got spare VGA cables and a 23pin to vga adapter, so I was thinking I'll just plug in to the VGA in on the Gonbes.

What I'm concerned about is that Ian Stedman's blog recommends a resistor on the Amiga's csync pin to lower the voltage to a safe level... will I need to do this if I want to instead use the H and V syncs from the Amiga's 23 pin video out?

and what about the R,G and B lines? I assume not as Ian doesn't seem to do this for his scart connectors...?

I have all the bits to make a cable for this, including the resistors. I could just try it but I'd rather save myself the effort of all that soldering

Thanks!

idrougge · 06 March 2017, 20:31

I don't think the VGA adapter even uses composite sync.

sirlemonhead · 06 March 2017, 20:44

I'm wondering if the H and V lines need resistors.

idrougge · 06 March 2017, 21:36

Not for normal VGA screens. They often do need buffering (74HCT08 or 7404), though.

sirlemonhead · 13 March 2017, 23:03

Cool, thanks

Why would they need buffering?

idrougge · 14 March 2017, 00:30

The Amiga might be fooled into thinking there's a genlock attached otherwise, going into an endless reboot loop.

Sanxion · 15 January 2018, 08:55

I have recently bought one of these and used a 23 pin to 15 pin converter (bought from AmigaKit) which I then connected to the VGA "in" socket on the board. I then connected a standard VGA monitor to the output. However, all I receive is some intermittent flickering and then "no signal" appears.

My question: does this mwthod work or are we supposed to connect a 23 pin D to the internal connector supplied with the board?

06 March 2017, 17:55	#1
sirlemonhead Registered User Join Date: Mar 2016 Location: Dublin Posts: 31	Amiga RGB to Gonbes 8200 vga in Hi, I've got one of those Gonbes boards but I don't have the header connector wires that typically come with them. I've got spare VGA cables and a 23pin to vga adapter, so I was thinking I'll just plug in to the VGA in on the Gonbes. What I'm concerned about is that Ian Stedman's blog recommends a resistor on the Amiga's csync pin to lower the voltage to a safe level... will I need to do this if I want to instead use the H and V syncs from the Amiga's 23 pin video out? and what about the R,G and B lines? I assume not as Ian doesn't seem to do this for his scart connectors...? I have all the bits to make a cable for this, including the resistors. I could just try it but I'd rather save myself the effort of all that soldering Thanks! Last edited by sirlemonhead; 06 March 2017 at 20:45.

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06 March 2017, 20:31	#2
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,332	I don't think the VGA adapter even uses composite sync.

06 March 2017, 20:44	#3
sirlemonhead Registered User Join Date: Mar 2016 Location: Dublin Posts: 31	I'm wondering if the H and V lines need resistors.

06 March 2017, 21:36	#4
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,332	Not for normal VGA screens. They often do need buffering (74HCT08 or 7404), though.

13 March 2017, 23:03	#5
sirlemonhead Registered User Join Date: Mar 2016 Location: Dublin Posts: 31	Cool, thanks Why would they need buffering?

14 March 2017, 00:30	#6
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,332	The Amiga might be fooled into thinking there's a genlock attached otherwise, going into an endless reboot loop.

15 January 2018, 08:55	#7
Sanxion Registered User Join Date: Jul 2017 Location: England Posts: 138	I have recently bought one of these and used a 23 pin to 15 pin converter (bought from AmigaKit) which I then connected to the VGA "in" socket on the board. I then connected a standard VGA monitor to the output. However, all I receive is some intermittent flickering and then "no signal" appears. My question: does this mwthod work or are we supposed to connect a 23 pin D to the internal connector supplied with the board?

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