Got 2 Asteroids PCBs to about 90% fixed:
1) Was watch-dogging. Clock was good. Working RAMs at D2 & E2 selected ok. ROM at C1 seemed to be selected ok. Activity on address lines and data lines. CPU was fine. Plugged in Paul Swan’s Arduino ICT and found I could address and read all RAMs & ROMs! LS139 at E4 was dead; pin 11 was stuck; that’s basically the IC that controls all the address decoding. Remaining issue on PCB shows text trailing downwards per letter and the copyright moving with an asteroid! Still investigating.
Text and copyright issue:
https://youtu.be/JLR7vBvIqOw
2) Beep codes suggest M4 vec RAM (2114) is dead. Swapped it and same issue. ICT says only R4 vec RAM can be read/write. LS32 at M5 was intermittent in verification; swapped and PCB back up and running. Remaining issue on PCB is very frustrating; at set intervals across the field there’s a very minor wiggle on both axis. Most obvious on player ship as it moves around. The defect stays at the location on the field rather than following the ship. If the ship stays still the defects also remain static.
Wiggle issue:
https://youtu.be/vqtbpsyPBRc
Any suggestions on the last 2 issues would be greatly received!Nes4life2018-04-02 22:55:16
1) Was watch-dogging. Clock was good. Working RAMs at D2 & E2 selected ok. ROM at C1 seemed to be selected ok. Activity on address lines and data lines. CPU was fine. Plugged in Paul Swan’s Arduino ICT and found I could address and read all RAMs & ROMs! LS139 at E4 was dead; pin 11 was stuck; that’s basically the IC that controls all the address decoding. Remaining issue on PCB shows text trailing downwards per letter and the copyright moving with an asteroid! Still investigating.
Text and copyright issue:
https://youtu.be/JLR7vBvIqOw
2) Beep codes suggest M4 vec RAM (2114) is dead. Swapped it and same issue. ICT says only R4 vec RAM can be read/write. LS32 at M5 was intermittent in verification; swapped and PCB back up and running. Remaining issue on PCB is very frustrating; at set intervals across the field there’s a very minor wiggle on both axis. Most obvious on player ship as it moves around. The defect stays at the location on the field rather than following the ship. If the ship stays still the defects also remain static.
Wiggle issue:
https://youtu.be/vqtbpsyPBRc
Any suggestions on the last 2 issues would be greatly received!Nes4life2018-04-02 22:55:16