I have a post over at English Amiga Board, but thought I would post here and see if I can get any leads on what to do. I have a Rev 4.4 Amiga 2000 board that worked when first tested. Battery leakage was minimal, best cosmetic board i have seen. So I cleaned up the leaked area, scratched away the mask, vinegar'ed up the board to neutralize the alkaline, and replaced the capacitors. When I went to power it back up I got nothing, just a black screen.
I have a Rev 4.3 board that was in worse shape and has bodge wires from torn traces and pads, but it worked, so it was going to be a backup board. Now I have found myself using the Rev 4.3 board to help troubleshoot this 4.4 board. Things that I have ruled out...
All custom chips are good (Plus cpu and BIOS, basically all socketed IC's are good)
Power supply is good
Replaced CPU socket
Replaced Gary socket (seemed it was not seated properly from factory, rasied a bit on one side)
Tried KS 2.04 and 1.3 along with DiagROM 1.2.1
Pulled buster completely, no change with DiagROM 1.2.1 installed
Made sure 5V was at all typical places on the board.
Pulled Agnus and made sure pins were making good contact, bent them out a bit to make sure.
Went over the whole board with magnifying glass on top and bottom looking for any cracks, solder joints, etc.
Checked for Clock and Reset and it is okay. Also counter showed the clock CPU pin 15 to be 7.159MHz
With Amiga Keyboard attached, the cap lock light does not flash, it does respond on and off when you press the caps lock, for about 8-10 cycles before locking up the light, the CTRL+Amiga+Amiga does reboot the system
The power LED is solid bright no pulsing or flashing
So what happens is the CPU goes into Halt on boot up. The only way I have found to keep the CPU from halting is when Gary and Paula are BOTH removed. It will still halt if one is left from the two. I know these two IC's are good, so I mimicked the same setup on the working Rev 4.3 board and took some measurements to compare between the two boards. Everything should have been the exact same, except the bad 4.4 board does not have the 1Meg Chip mod done yet. I attached a PDF with my summary of what I found, and it looks like some logic is in different states in some of the 74 logic chips. I tested a few random IC's, but I am happy to check anything if someone can suggest a specific component we need to focus on.
So far only have used the mono composite out for testing til I can get a commodore RGB monitor hopefully next.
The different shade of green is the UV mask I reapplied over where I scraped off the blackened mask. It looks kind of funny with the light reflecting, but it all is good. Basically the only green gunk and damage was just in that one small area from the best I can tell, so I am not sure if this black screen issue is from the battery damage.
Appreciate any help on what maybe to check moving forward. I have been working on this board for about 2 weeks and kind of hit a wall on what to do to resolve the cpu halt.
Thanks
I have a Rev 4.3 board that was in worse shape and has bodge wires from torn traces and pads, but it worked, so it was going to be a backup board. Now I have found myself using the Rev 4.3 board to help troubleshoot this 4.4 board. Things that I have ruled out...
All custom chips are good (Plus cpu and BIOS, basically all socketed IC's are good)
Power supply is good
Replaced CPU socket
Replaced Gary socket (seemed it was not seated properly from factory, rasied a bit on one side)
Tried KS 2.04 and 1.3 along with DiagROM 1.2.1
Pulled buster completely, no change with DiagROM 1.2.1 installed
Made sure 5V was at all typical places on the board.
Pulled Agnus and made sure pins were making good contact, bent them out a bit to make sure.
Went over the whole board with magnifying glass on top and bottom looking for any cracks, solder joints, etc.
Checked for Clock and Reset and it is okay. Also counter showed the clock CPU pin 15 to be 7.159MHz
With Amiga Keyboard attached, the cap lock light does not flash, it does respond on and off when you press the caps lock, for about 8-10 cycles before locking up the light, the CTRL+Amiga+Amiga does reboot the system
The power LED is solid bright no pulsing or flashing
So what happens is the CPU goes into Halt on boot up. The only way I have found to keep the CPU from halting is when Gary and Paula are BOTH removed. It will still halt if one is left from the two. I know these two IC's are good, so I mimicked the same setup on the working Rev 4.3 board and took some measurements to compare between the two boards. Everything should have been the exact same, except the bad 4.4 board does not have the 1Meg Chip mod done yet. I attached a PDF with my summary of what I found, and it looks like some logic is in different states in some of the 74 logic chips. I tested a few random IC's, but I am happy to check anything if someone can suggest a specific component we need to focus on.
So far only have used the mono composite out for testing til I can get a commodore RGB monitor hopefully next.
The different shade of green is the UV mask I reapplied over where I scraped off the blackened mask. It looks kind of funny with the light reflecting, but it all is good. Basically the only green gunk and damage was just in that one small area from the best I can tell, so I am not sure if this black screen issue is from the battery damage.
Appreciate any help on what maybe to check moving forward. I have been working on this board for about 2 weeks and kind of hit a wall on what to do to resolve the cpu halt.
Thanks
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