Vertical bars from CompServ scan doubler

12 July 2018, 16:52

Hi everyone!

I've recently added a CompServ v1.1 scan doubler to my A4000 desktop. It works and I can see AGA modes on a VGA monitor, and through a Cybervision 64, but with one problem.

Solid blocks of colour have repeated vertical bars running through them. These are static and consistent, and appear when viewing either through the Cybervision or through just the scan doubler.

A 15Hz monitor attached to the RGB output shows no problems, so this is likely an issue with the scan doubler or the video port itself. Would anybody have any suggestions on where to look to diagnose and hopefully resolve whatever causes this?

Jope · 12 July 2018, 21:00

Check behind the zorro riser for bent/shorted pins first.

14 July 2018, 20:13

Hi Jope,
Whereabouts should I look exactly? On the A4000 motherboard or on the riser itself? I can't see anything obviously wrong at the moment visually.

stachu100 · 14 July 2018, 23:39

Check on CRT VGA monitor. Not LCD.

Jope · 15 July 2018, 10:39

I reread your question and came to the same conclusion as Stachu.. Probably scaling side effects.

The short circuits I referred to are on the solder side of the riser, around the area where the hard drives are.

16 July 2018, 22:32

Thanks for the suggestions. I'll see if I can hunt down a CRT monitor to test with!

amigoun · 16 July 2018, 23:15

Also good to try is to play with the pixel clock/phase settings of your LCD, maybe you can tune the picture to acceptable results.

utri007 · 17 July 2018, 01:52

Quote:

Originally Posted by amigoun

Also good to try is to play with the pixel clock/phase settings of your LCD, maybe you can tune the picture to acceptable results.

This how I fixed vertical bars problem with Micronik scandy and DCE scanmagic

idrougge · 17 July 2018, 02:18

Was it only I who interpreted "VGA monitor" as "CRT"?

stachu100 · 17 July 2018, 02:26

Quote:

Originally Posted by idrougge

Was it only I who interpreted "VGA monitor" as "CRT"?

Lack of pictures from your side.........
1 picture is better than 1000 words.

12 July 2018, 16:52	#1
Vulpine Posts: n/a	Vertical bars from CompServ scan doubler Hi everyone! I've recently added a CompServ v1.1 scan doubler to my A4000 desktop. It works and I can see AGA modes on a VGA monitor, and through a Cybervision 64, but with one problem. Solid blocks of colour have repeated vertical bars running through them. These are static and consistent, and appear when viewing either through the Cybervision or through just the scan doubler. A 15Hz monitor attached to the RGB output shows no problems, so this is likely an issue with the scan doubler or the video port itself. Would anybody have any suggestions on where to look to diagnose and hopefully resolve whatever causes this?

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12 July 2018, 21:00	#2
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	Check behind the zorro riser for bent/shorted pins first.

14 July 2018, 20:13	#3
Vulpine Posts: n/a	Hi Jope, Whereabouts should I look exactly? On the A4000 motherboard or on the riser itself? I can't see anything obviously wrong at the moment visually.

14 July 2018, 23:39	#4
stachu100 Registered User Join Date: Mar 2009 Location: Poland Posts: 339	Check on CRT VGA monitor. Not LCD.

15 July 2018, 10:39	#5
Jope - Join Date: Jul 2003 Location: Helsinki / Finland Age: 43 Posts: 9,861	I reread your question and came to the same conclusion as Stachu.. Probably scaling side effects. The short circuits I referred to are on the solder side of the riser, around the area where the hard drives are.

16 July 2018, 22:32	#6
Vulpine Posts: n/a	Thanks for the suggestions. I'll see if I can hunt down a CRT monitor to test with!

16 July 2018, 23:15	#7
amigoun Registered User Join Date: May 2010 Location: Czech Rep Posts: 599	Also good to try is to play with the pixel clock/phase settings of your LCD, maybe you can tune the picture to acceptable results.

17 July 2018, 02:18	#9
idrougge Registered User Join Date: Sep 2007 Location: Stockholm Posts: 4,332	Was it only I who interpreted "VGA monitor" as "CRT"?

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