Another A500...another problem...

[Noster]

Hi

I found this in the Amiga Guru Book:

Start-up diagnostics:

Green - error in the lowest 256 kilobytes of Chip memory. This might also be caused by a defective CIA-A (memory overlay bit, for example) or Agnus chip


I have an A2K where also a pin of the Agnus-socket has been broken, I managed to bend a tiny wire and press it between the pin of the Agnus and the remaining rest of the broken pin in the socket... and it works :-D
I think the A2K should not be shocked to hard, but it works now for nearly half a year without any further problems.

Noster

[Noster]

Hi

@redrumloa
>From a quick check it looks like what I suspected is correct. It looks like someone tried to do a PAL hack

Yeah it looks so...

> ...it should still work and should still default to NTSC.

Yes, it should still work, but default to PAL !!!

@Gavilan

What do you have in Argentina ? PAL or NTSC ?
I would try to replace the CIA 8520. There should be two of them on the board, don't know which of them is the CIA-A and which is the CIA-B, but you've said you have more Amigas, so replace both of them and test which one is defect.
Maybe the error is a missing memory expansion and the A500 is reworked to 1MB chip and the Agnus is missing the second 512kB memory ?

Noster

[Noster]

Hi

@melott

> I soldered a stiff piece of copper wire on the little stub left on the chip

In the case of Gavilan's A500 the socket is also damaged (as in my A2000) and there is absolutely no space for a soldering iron. If it needs to be repaired, the whole socket has to be desoldered and that is not a job for a hobbyist :-(

Noster

[Noster]

Hi

I meant you should take two CIAs from one of your working A500 and place them in this board for testing. If the board works with them, you could check out which of the two replaced CIAs is defect.
I don't really think the A500 mobo is destroyed, I think there is a chance that it is patched to 1MB chip-RAM and you should replace the CIAs, use the Agnus with the broken pin, insert a A501 memory expansion and try to run...

Noster