A better CGA to VGA board for £25 ???

22 May 2011, 21:40

Does anyone know if the following CGA to VGA board would be compatible with the A1200?

http://cgi.ebay.co.uk/RGBs-EGA-CGA-Y...-/190529433177

The converter board is just under £25 which is much more attractive than the $80 one I have been seeing and hearing about.

What do you all think?

Calabazam · 23 May 2011, 09:01

Don't know but the seller's rating of 90,7% is very low by ebay standards.

Jope · 23 May 2011, 09:31

Buy one and see. Probably won't perform very well - either you get colour banding or jerky scrolling.

Hewitson · 23 May 2011, 10:06

I believe they would in fact work, I've seen countless people use them with JAMMA boards. Wouldn't recommend them though, as they'll convert the 50hz to 60hz resulting in a terrible jerkiness.

CGA often refers to just the horizontal refresh rate (15khz), nothing to do with colours, etc.

23 May 2011, 10:10

Quote:

Originally Posted by alexh

Since this was posted, Ian Steadman, well respected Amiga hardware hacker, has posted another thread in which he explains why these boards don't work with Amiga.

http://eab.abime.net/showthread.php?t=59380

(Though why he didn't post here I dunno?)

Damn I got all excited when i found this. Thanks for finding that link for us alexh.

23 May 2011, 10:13

Quote:

Originally Posted by Hewitson

I believe they would in fact work, I've seen countless people use them with JAMMA boards. Wouldn't recommend them though, as they'll convert the 50hz to 60hz resulting in a terrible jerkiness.

CGA often refers to just the horizontal refresh rate (15khz), nothing to do with colours, etc.

According to that post it would work but you will only get 16 colours... Ah back to the days of the C64 and Speccy, I could actually produce good graphics back then! ;-)

Hewitson · 23 May 2011, 11:32

Quote:

Originally Posted by alexh

If that is true, then the spec is wrong. Give us a link.

[ Show youtube player ]

[ Show youtube player ]

http://www.jammaboards.com/store/cga.../prod_291.html

alexh · 23 May 2011, 12:31

The spec has to be wrong... get one and tell us how it works out

RedskullDC · 23 May 2011, 13:53

Hi Alexh, et al.

Quote:

Originally Posted by alexh

The spec has to be wrong... get one and tell us how it works out

I ordered a couple last week, to try with a Tandy MC-10 and a TI 99/4A.

just waiting for them to arrive...

Will gove them a go on the Miggy as well...
Will post here when wired up.

Cheers,
Red

Jope · 23 May 2011, 14:13

Show us some beautiful AGA gradients. ;-)

Hewitson · 23 May 2011, 15:22

Quote:

Originally Posted by Jope

Show us some beautiful AGA gradients. ;-)

Quote:

Originally Posted by http://www.jammaboards.com/store/cga/ega/yuv-to-vga-converter-pcb-gbs-8220/prod_291.html

True digital 24-bit A/D converter for true 16.7-million color conversion.

..

Calgor · 23 May 2011, 18:14

This guy tried to hook up an Atari ST to the GBS-8220 but looks like he got white displaying as pink:
http://info-coach.fr/atari/hardware/video.php#GBS

Perhaps this was a result of RGB into inputs expecting YUV?
http://www.joemaller.com/fcp/fxscript_yuv_color.shtml

Well, maybe there is a setting to adjust on the converter? I don't know much about Jamma boards or what they output compared with an Amiga or Atari ST. Look forward to RedskullDC's results.

alexh · 23 May 2011, 21:01

Quote:

Originally Posted by Calgor

I don't know much about Jamma boards or what they output compared with an Amiga or Atari ST.

AFAIK in low-res they are practically identical. RGBHV @ 15KHz Horizontal, 50Hz Vertical. Perhaps the voltages are slightly different? We'll see.

desantii · 24 May 2011, 00:01

I bought one some moths ago, works great(see pic 640x400 res), but.... after 10-15min the image starts loosing sync (see last pic). I used a 9 pin connector to a 23-9 amiga cable

Hewitson · 24 May 2011, 05:18

Quote:

Originally Posted by alexh

AFAIK in low-res they are practically identical. RGBHV @ 15KHz Horizontal, 50Hz Vertical. Perhaps the voltages are slightly different? We'll see.

Standard for arcade boards is 60hz vertical, negative composite sync.

The voltages are quite a bit higher, usually resistors/pots are needed on the RGB lines to reduce the brightness down to acceptable levels for a TV.

RedskullDC · 01 June 2011, 18:04

Hi All,

The adapter boards arrived today.
(Seller on Ebay appears a bit shonky, but my stuff arrived pretty quickly. Use Paypal to cover yourself in case!).

They came with no instruction manual

, but it wasn't too difficult to find one online: http://info-coach.fr/atari/hardware/video/GBS-8200.pdf

Wired up the Red, Green, Blue, HSync, VSync, Gnd signals to the 8 pin plug supplied (P11), after carefully moving the Gray HSYNC wire to the correct place on the connector. Mine came with the grey wire connected to the composite sync pin.

Plugged it into my small Phillips test monitor, and got the dreaded "pink flickering that Calgor mentioned in a post above.

Then I disconnected the HSYNC and VSYNC lines, and just tried using the composite SYNC line from the Amiga RGB port to the composite SYNC line on the 8-pin P11 plug. Fired it back up, success!!

Couple of pics attached to show the unit in operation attached to the 1200.One in PAL HIRES, the other in PAL SUPER-HIRES LACED.
The LACED modes are de-interlaced when displayed.

Yes, it does happily sync up to both NTSC(60Hz) and PAL(50Hz) signals!
When switching modes from PAL <> NTSC, the unit did get "lost". A quick push of the 'auto' button brought it back in sync.

The PAL modes required a minimum of 800x600 output from the unit, whereas the NTSC modes would work ok on 640x480 output.
The higher resolution modes required a correspondingly higher output mode. Some playing around may be required to establish the best screenmode/output mode combinations.

The quality on screen is very good actually, the pics I have attached don't really do it justice. (ignore the herringbone patterns for example, just an artifact of the crappy monitor/campera combo...
Desantii's photos above look far better than mine

I haven't noticed any of the lost sync problems that Desantii mentioned, though I haven't run it for any length of time. The chip with the heatsink attached did get a little warm, so it may be heat related. A small fan may be the go.

All in all, a very cheap solution which provides a good quality output.

Cheers,
Red

alexh · 01 June 2011, 18:09

Sounds good. I have some AGA test patterns somewhere. Three screens each with 256 shades of RED, GREEN and BLUE going left to right. The more you can count on your screen the better the ADC/DAC in the device. Should be pretty obvious if it is not "24-bit" or close.

desantii · 03 June 2011, 23:08

I did add a larger heatsink, will try a fan this weekend

RedskullDC, what voltage are you using an input?

RedskullDC · 04 June 2011, 02:40

Hi Desantii,

Quote:

Originally Posted by desantii

RedskullDC, what voltage are you using an input?

I'm using a 5V switchmode plug-pack with 2.5A output.

Cheers,
Red

desantii · 04 June 2011, 07:22

I was using 9V, I'll try to find a 5v to test

22 May 2011, 21:40	#1
DelboyJay Posts: n/a	A better CGA to VGA board for £25 ??? Does anyone know if the following CGA to VGA board would be compatible with the A1200? http://cgi.ebay.co.uk/RGBs-EGA-CGA-Y...-/190529433177 The converter board is just under £25 which is much more attractive than the $80 one I have been seeing and hearing about. What do you all think?

01 June 2011, 18:04	#16
RedskullDC Digital Corruption Join Date: Jan 2007 Location: Dorrigo/Australia Age: 60 Posts: 355	Hi All, The adapter boards arrived today. (Seller on Ebay appears a bit shonky, but my stuff arrived pretty quickly. Use Paypal to cover yourself in case!). They came with no instruction manual , but it wasn't too difficult to find one online: http://info-coach.fr/atari/hardware/video/GBS-8200.pdf Wired up the Red, Green, Blue, HSync, VSync, Gnd signals to the 8 pin plug supplied (P11), after carefully moving the Gray HSYNC wire to the correct place on the connector. Mine came with the grey wire connected to the composite sync pin. Plugged it into my small Phillips test monitor, and got the dreaded "pink flickering that Calgor mentioned in a post above. Then I disconnected the HSYNC and VSYNC lines, and just tried using the composite SYNC line from the Amiga RGB port to the composite SYNC line on the 8-pin P11 plug. Fired it back up, success!! Couple of pics attached to show the unit in operation attached to the 1200.One in PAL HIRES, the other in PAL SUPER-HIRES LACED. The LACED modes are de-interlaced when displayed. Yes, it does happily sync up to both NTSC(60Hz) and PAL(50Hz) signals! When switching modes from PAL <> NTSC, the unit did get "lost". A quick push of the 'auto' button brought it back in sync. The PAL modes required a minimum of 800x600 output from the unit, whereas the NTSC modes would work ok on 640x480 output. The higher resolution modes required a correspondingly higher output mode. Some playing around may be required to establish the best screenmode/output mode combinations. The quality on screen is very good actually, the pics I have attached don't really do it justice. (ignore the herringbone patterns for example, just an artifact of the crappy monitor/campera combo... Desantii's photos above look far better than mine I haven't noticed any of the lost sync problems that Desantii mentioned, though I haven't run it for any length of time. The chip with the heatsink attached did get a little warm, so it may be heat related. A small fan may be the go. All in all, a very cheap solution which provides a good quality output. Cheers, Red Attached Thumbnails

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23 May 2011, 09:01	#2
Calabazam Registered User Join Date: Sep 2005 Location: France Posts: 445	Don't know but the seller's rating of 90,7% is very low by ebay standards.

23 May 2011, 09:31	#3
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,837	Buy one and see. Probably won't perform very well - either you get colour banding or jerky scrolling.

23 May 2011, 10:06	#4
Hewitson Registered User Join Date: Feb 2007 Location: Melbourne, Australia Age: 41 Posts: 3,771	I believe they would in fact work, I've seen countless people use them with JAMMA boards. Wouldn't recommend them though, as they'll convert the 50hz to 60hz resulting in a terrible jerkiness. CGA often refers to just the horizontal refresh rate (15khz), nothing to do with colours, etc.

23 May 2011, 12:31	#8
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,279	The spec has to be wrong... get one and tell us how it works out

23 May 2011, 14:13	#10
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,837	Show us some beautiful AGA gradients. ;-)

23 May 2011, 18:14	#12
Calgor (Amigas && Amigos)++ Join Date: Sep 2005 Location: Anrea Posts: 999	This guy tried to hook up an Atari ST to the GBS-8220 but looks like he got white displaying as pink: http://info-coach.fr/atari/hardware/video.php#GBS Perhaps this was a result of RGB into inputs expecting YUV? http://www.joemaller.com/fcp/fxscript_yuv_color.shtml Well, maybe there is a setting to adjust on the converter? I don't know much about Jamma boards or what they output compared with an Amiga or Atari ST. Look forward to RedskullDC's results.

24 May 2011, 00:01	#14
desantii Registered User Join Date: Oct 2009 Location: Oswego, IL Posts: 125	I bought one some moths ago, works great(see pic 640x400 res), but.... after 10-15min the image starts loosing sync (see last pic). I used a 9 pin connector to a 23-9 amiga cable

01 June 2011, 18:09	#17
alexh Thalion Webshrine Join Date: Jan 2004 Location: Oxford Posts: 14,279	Sounds good. I have some AGA test patterns somewhere. Three screens each with 256 shades of RED, GREEN and BLUE going left to right. The more you can count on your screen the better the ADC/DAC in the device. Should be pretty obvious if it is not "24-bit" or close.

03 June 2011, 23:08	#18
desantii Registered User Join Date: Oct 2009 Location: Oswego, IL Posts: 125	I did add a larger heatsink, will try a fan this weekend RedskullDC, what voltage are you using an input?

04 June 2011, 07:22	#20
desantii Registered User Join Date: Oct 2009 Location: Oswego, IL Posts: 125	I was using 9V, I'll try to find a 5v to test

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