A2000 Rev. 6 not booting

[roadrash]

Originally Posted by Vypr

Have you checked if RP900 is working properly? It looks like there's a chunk out of it at the top.

I see what you mean but its just a mark on the top and doesn't go into it.

[roadrash]

Originally Posted by RetroPassionUK

Sorry to state the obvious you have reseated all the chips including agnus?

Thanks all help is welcome but yes I have tried reseating all chips including Agnes. I still have another working A2000 so could try swapping over all chips one by one. I did this with the processor but not any of the others.

[roadrash]

Just replaced that capacitor and swapped Gary over from my working A2000 and this one is still not booting up and just steady power LED and not flashing. Which chip would be the next most likely one to stop it booting if it was faulty.

[roadrash]

I just checked all the capacitors that were replaced and did find a couple that had cracked pads and repaired them. also found one thin track under power connector that was damaged on 1st pin in row if 4 and jumped it will wire.
I really thought I had sorted it this time but sadly not. I am out of ideas now and after 2 full days checking everything and even comparing readings from my other working rev 6.2 working A2000 motherboard I cannot find any faults. I did try swapping some chips too but nothing worked.
There are no shorts and it will power up with a steady red power led but not alternate brightness as normal. I can leave it powered up for hours and all chips are warm but not really hot.
Looks like I am going to have to give up with this one sadly as it passes every test now I was told to check and getting no where now. Might stick in cupboard for another time or flog it off on Ebay spares or repair.
If anyone else has any other things I can test or a boot up checklist I can go through I would be grateful

[LIV2]

I would do the following even if some of the steps have already been done

1: Check voltages
2: Check the Clock pin of the CPU with an oscilloscope
3: Check that both reset and halt pins are starting low and both going high some time (couple hundred ms) after power up
4: Check that they stay high - if the CPU is hitting an exception it will halt itself and take HLT low while RESET will be high
5: With an oscilloscope check the AS and DTACK pins on the CPU to make sure it isn't getting stuck with AS low but no DTACK
6: With an oscilloscope Check if A1, UDS, AS etc are changing
7: Check OVL connectivity between Gary pin 30 and Odd CIA (U300) Pin 2
8: Check with oscilloscope that OVL is high at reset and goes low shortly afterwards
9: Check continuity between ROM pin 12 and Gary Pin 21

I will try to think of anything else but if all of these are OK you should be seeing more signs of life out of your machine...