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General Category => Technical Support => Topic started by: davdav79 on 05:15, 19 February 16

Title: Vertical lines on Plus
Post by: davdav79 on 05:15, 19 February 16
Hi! I have these machines:

CPC6128, no problems... great picture
6128PLUS on RGB on a TV it gives me heavy vertical lines issues, very annoying
464PLUS on RGB on a tv gives me also vertical lines, but not too much as the 6128plus

I'm using a RGB scart cable from retrocomputer shack and a jamma power supply for the 5V line

Any idea? thanks
Title: Re: Vertical lines on Plus
Post by: Bryce on 10:15, 19 February 16
Hi,
     yes, it's due to Alan sugar scraping the last penny of profit out of the machine and removing the capacitors from the RGB outputs. Not noticable on a CRT, but it shows up on modern TVs. More info here: Dirty video on 6128 Plus RGB Scart (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/video-not-clean-on-6128-plus-rgb-scart/msg48776/#msg48776)

Bryce.
Title: Re: Vertical lines on Plus
Post by: Kris on 10:40, 19 February 16
Each Plus owner should apply this fix; it's a shame to have a video signal output without "filtering" ;)

Title: Re: Vertical lines on Plus
Post by: ||C|-|E|| on 10:50, 19 February 16
Mine actually suffers from this... I should fix it, but I am considering to use a proper CRT instead  :-X
Title: Re: Vertical lines on Plus
Post by: davdav79 on 11:58, 19 February 16
Hi,
     yes, it's due to Alan sugar scraping the last penny of profit out of the machine and removing the capacitors from the RGB outputs. Not noticable on a CRT, but it shows up on modern TVs. More info here: Dirty video on 6128 Plus RGB Scart (http://www.cpcwiki.eu/forum/amstrad-cpc-hardware/video-not-clean-on-6128-plus-rgb-scart/msg48776/#msg48776)

Bryce.

So, should I add a 'star' of three 220 pF capacitors from ground to each RGB line?
Title: Re: Vertical lines on Plus
Post by: Bryce on 12:22, 19 February 16
Yes.

Bryce.
Title: Re: Vertical lines on Plus
Post by: davdav79 on 13:30, 19 February 16
I'll Try. thanks :)

(But why on the 6128+ the issue is bigger than the issue on the 464+ ? maybe different board revisions?)
Title: Re: Vertical lines on Plus
Post by: Bryce on 14:31, 19 February 16
No idea. The PCBs are identical so it can only be down to the tolerances of the parts used.

Bryce.
Title: Re: Vertical lines on Plus
Post by: seanb on 13:13, 20 February 16
I've been meaning to ask this question myself.
Glad there's an answer even though I did see Bryces earlier answer on the dirty picture thread a long time ago.

That's one hardware problem hopefully sorted.
Thanks everyone.