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Amiga computer related discussion => Amiga Hardware Issues and discussion => Topic started by: AmigaPixel on May 29, 2011, 09:00:37 AM

Title: Issue with RCA out on A2000
Post by: AmigaPixel on May 29, 2011, 09:00:37 AM

My A2000 composite jack seems to have gone bad. I was attempting to use it until I can get a RGB->S-video/composite adapter. I can see WorkBench but it scrolls constantly. I tried connecting it to two different TVs and got the same results. Could this be the Denise chip or one of the other chips that controls the RCA video out? I should add that the PSU is starting to fail, the system boots up fine unless I plug in the power to the CD-Writer.

Title: Re: Issue with RCA out on A2000
Post by: psxphill on May 29, 2011, 10:00:59 AM

Quote from: AmigaPixel;641050

My A2000 composite jack seems to have gone bad. I was attempting to use it until I can get a RGB->S-video/composite adapter. I can see WorkBench but it scrolls constantly.

Sounds like you might have the wrong video standard set. Are you sure you've got the correct pal/ntsc setting?

Title: Re: Issue with RCA out on A2000
Post by: AmigaPixel on May 30, 2011, 04:49:26 AM

Well I have always kept in NTSC, but I guess it is possible I set it to boot it into PAL before I lost my monitors.

Title: Re: Issue with RCA out on A2000
Post by: magnetic on May 30, 2011, 07:04:28 AM

yes i agree it sounds like a frequency problem (pal instead of ntsc) boot with a pal game if you have one.

Title: Re: Issue with RCA out on A2000
Post by: guest7146 on May 30, 2011, 10:58:28 AM

If you set the wrong colour standard then usually you still see a stable picture but it's a bit grainy and lacks any colour information (you see B&W).

If the screen is rolling then this is usually down to loss of sync-pulse information.

In order to proceed I'd want to see the video output on a scope, but I guess you're not in posession of that sort of equipment?

AH

Title: Re: Issue with RCA out on A2000
Post by: JimS on May 30, 2011, 03:35:34 PM

I believe the 2000's composite output is in B&W.

Title: Re: Issue with RCA out on A2000
Post by: Darrin on May 30, 2011, 05:01:49 PM

Quote from: JimS;641393

I believe the 2000's composite output is in B&W.

Correct.  Couple that with A2000s being either PAL or NTSC and you end up with the rolling screen.

My A2000 was originally NTSC, but had the PAL/NTSC Agnus and with the aid of a scaple it was quick to convert from one to the other and a jumper could reverse the process if necessary.

Title: Re: Issue with RCA out on A2000
Post by: guest7146 on May 30, 2011, 06:27:44 PM

Quote from: JimS;641393

I believe the 2000's composite output is in B&W.

Is it indeed? So there's no colour information included with the composite output on the A2K anyway?

So why, then, does setting PAL/NTSC on the machine make any difference at all to the output? And why should the symptom be picture rolling? It must have something to do with the sync-pulse information.

AH

Title: Re: Issue with RCA out on A2000
Post by: JimS on May 30, 2011, 06:44:50 PM

Yes, the horizontal and vertical scan rates are different as well as the way the color is encoded. Vertical sync is 50Hz in PAL and 60 for NTSC. Some monitors can deal with that, some can't.

Title: Re: Issue with RCA out on A2000
Post by: guest7146 on May 30, 2011, 08:07:52 PM

Quote from: JimS;641419

Yes, the horizontal and vertical scan rates are different as well as the way the color is encoded. Vertical sync is 50Hz in PAL and 60 for NTSC. Some monitors can deal with that, some can't.

Ah yes okay, that makes perfect sense then.  I'd have thought most modern TVs would deal with it though.

AH.