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Old 28 February 2021, 13:56   #1
ikorodu
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A600 colour strange over RGB

Hi everybody!

I've recently set up my a600 that was recapped by RetroPassion just before Christmas.

I now have a strange colour issue over Rgb to scart that I didn't have before. Colours over composite look OK.

Can anyone give me a starting place to look at?

Attached are two images one over Rgb scart the other composite.

Thanks!
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Old 28 February 2021, 14:11   #2
kirk_m
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I had a 1200 that was outputting video that was too bright. I fixed it by following the info in this blog (replacing the reference voltage diode):

https://www.tsb.space/knowledge-base...-video-signal/
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Old 28 February 2021, 14:14   #3
solarmon
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Looks like the blue colour not getting through - so look at the schematics and amigapcb.org (for rev 2A) to check the traces/pins/components associated with it.

https://www.amigawiki.org/doku.php?i...chematics#a600



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Old 28 February 2021, 17:37   #4
ikorodu
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Thanks all for suggestions so far.

I have found this video

[ Show youtube player ]

Which shows a repair for loss of red. Using this and the advice above I hope I will find a solution.
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Old 28 February 2021, 18:27   #5
supaduper
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Have you tried another RGB cable ?, as some of them are poorly made and wires in the 23 pin hood can come loose and short out especialy if the lead is loose/floppy where it actually enters the hood, I know because it has happend to me
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Old 28 February 2021, 18:39   #6
alexh
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Does it flicker when the HDD, PCMCIA or FDD is being used? mine is like that. It's not caps.
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Old 28 February 2021, 18:55   #7
ikorodu
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Have tried the cable on my a500 and a1200 without problems.

Don't recall any flickering. Picture is quite steady, just wrong colour!
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Old 28 February 2021, 19:08   #8
ikorodu
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I have just noticed in the picture attached that I think I have a component missing!

Perhaps this was removed during the recap and never replaced? I think this is on the blue line to the rgb connector

Can anyone advise where I could get this transistor from in the UK?
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Old 28 February 2021, 19:34   #9
MrClump
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Yes Q233 should be there and is related to the blue signal on the RGB output so that'll be your problem. The picture below shows it in place on an A600, ignore the missing caps, it's in the middle of being recapped. It's a standard off the shelf transistor, an NPN 2N3904 SOT23, depending on your soldering skills you may not enjoy the job of soldering a new one on.

It probably came off when the caps were being removed, and if he tested it afterwards with composite may not have noticed. I am sure if you talk to Steve at Retro Passion he will sort you out.
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Old 02 March 2021, 11:57   #10
ikorodu
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Have ordered the required transistor and will attempt my first surface mount soldering!
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Old 02 March 2021, 21:35   #11
MrClump
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Quote:
Originally Posted by ikorodu View Post
Have ordered the required transistor and will attempt my first surface mount soldering!
It looks like there is already solder on the pads, so you might get away with just dabbing the iron on it to melt it.
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Old 02 March 2021, 22:05   #12
ikorodu
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The results of my soldering are so bad that I refuse to share. But it worked! See attached. Thanks all for their advice.
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Last edited by ikorodu; 03 March 2021 at 08:04.
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Old 02 March 2021, 22:32   #13
MrClump
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Quote:
Originally Posted by ikorodu View Post
The results of my soldering are so bad that I refuse to share. But it worked! See attached. Thanks all for their advice.
Nobody is going to see it, and it works that's all that matters!
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