A1200 - interference during HD access

[dougal]

Its only a slightly annoying thing ,

But when the HD is accessing on my A1200 , i get a slight interference on the screen .

Its only slight . I have tried using an A500 PSU just in case it was lack of power , but still the same .

[a1200]

Its probably RF from the HDD/IDE interface leaking into the modulator or RGB circuits, or if you have removed the top shield, could be being picked up in the coax/RGB cable themselves.

If you are using RF, try switching to a RGB to SCART cable, which will give you a better picture anyway. Ferrite rings on cables and suchlike can all help to reduce interference.

Also, keep your IDE cable as short as possible, the standard IDE cable for an A600/A1200 is like an inch long. If it is longer, it might be running past components that are part of the video output, and might be picking the interference up internally.

I have seen this before, and if you are using RF, and cannot use SCART, another thing to do is use an external modulator from an A500, which you plug into the RGB port. The external modulators seem to be of better quality anyway.

Hope you get your problem sorted soon!

[rkauer]

 Depending on what A1200 revision board you have, there is a hack on Aminet called flickfix: it is a mere capacitor soldered on two pads near Lisa and stops that annoying flickering.

 Also check the power supply voltage levels (specially the +5V line), who needs to be in the 4.8~5.2V and stable.

[dougal]

It is connected using the RGB (DB23) so i dont think it is anything to do with RF .

Maybe its the voltage thing

I'll take a look .

[CLS2086]

Or dying caps ...  ;-)