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Old 21 January 2013, 18:22   #1
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amiga 1200 screen pulsating

i am building an a1200 tower project, have got pc psu wired up and working but amiga screen pusates and writing is hazey am using a scart lead to connect to tv - is this a power problem or a motherboard problem ?
i am using a at psu with wires connected and voltages checked
+12v reading 11.54v
-12v reading -11.6v
+5v reading +4.8v
-5v reading -4.76v
shield wire not connected.
has anyone got any suggestions ?

Last edited by freaky-beardy; 21 January 2013 at 21:37.
Old 25 January 2013, 15:37   #2
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That +5v is a bit too low for my liking, but it may not be the cause of the problem. Are you able to provide a picture, or preferably a short video clip of the problem?
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Old 25 January 2013, 16:39   #3
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If it looks like a sinosoidal pulsation, I'd think it could be a grounding problem. If it is picking up 50 Hz noise from the environment, it would be async to the 50 Hz picture being sent to the TV, thus creating a slow modulation.

I don't think it should be the PSU voltage, unless it has a lot of ripple on it.
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Old 26 January 2013, 10:53   #4
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have rechecked all connections and added a harddrive and cd rom via an ide-fix board and everything seems to be ok now, i can only assume i must have had a dodgey connection somewhere, thankyou for your suggestions.

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