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Old 30 April 2015, 13:23   #13
mark_k
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Join Date: Aug 2004
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Quote:
Originally Posted by grizzlyaddams View Post
Does anyone think it's safe to say with certainty that this A520 does me no good? I discussed a refund with the seller and he already refunded my money, and I told him I would send it back if he did, but did not expect him to right away! It was actually kind of cheap.
If you don't want to send it back, I've been looking at the A520 PCB pics at amiga.resource.cx and the MC1377 datasheet.

I think you could modify your PAL A520 to NTSC by doing this:
  • Replace the 4.43MHz crystal with a 3.58MHz crystal one.
  • Connect pin 20 of the MC1377 chip to ground. If you look at the PCB underside, you'll see a trace running from pin 20. Scratch away the solder mask over the end of that and the opposite site, and put a blob of solder to bridge the gap.
  • According to the MC1377 datasheet you should also change a couple of capacitor values in the filter circuit between pins 10 and 13. However you could probably skip that and still get a colour picture. (Assuming the A520 circuit is similar.)
In July last year quarkx mentioned having some NTSC A520s for sale.

And there are details on how to convert a (PAL) A520 to output S-video at http://members.iinet.net.au/~davem2/overclock/A520.html
The author of that mentions trying the first two steps above to convert a PAL A520 to NTSC and that it didn't work for him...
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