| Arcade Collecting > Restorations & repair |
| NPs Paperboy Restoration |
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| RetroACTIVE:
I know zilch about PaperBoy... but those images seem typical of RAM / RAM addressing defects... probably not voltage at this point. |
| ChadTower:
--- Quote from: RetroACTIVE on September 15, 2008, 12:18:02 pm ---I know zilch about PaperBoy... but those images seem typical of RAM / RAM addressing defects... probably not voltage at this point. --- End quote --- I'd make sure the RAM is getting proper voltages first... slight undervoltages can cause inconsistent RAM behaviour, I think. |
| Neverending Project:
--- Quote from: ChadTower on September 15, 2008, 01:17:12 pm ---I'd make sure the RAM is getting proper voltages first... slight undervoltages can cause inconsistent RAM behaviour, I think. --- End quote --- Without a scope, what is the best way to check these? If I am understanding the schematic correctly, the RAM chips (6116) do not have a +5V line - they read/write when the signal lines are high (or low, depending on the signal). So without a scope, I could only check that there is activity on the line - not what the voltage is, am I correct? I could check the +5V at the processor chip, anywhere else (besides the test points)? Also, what would be considered slight? Attached is a pic of one of the 6116 circuits to explain what I am talking about. |
| ChadTower:
Hrm. That's probably wading past the water levels for what I know how to troubleshoot. Wish I could help a bit more but at least know I'll be reading your exploits so I can learn from them. ;D |
| TheShanMan:
Not all pins are accounted for in that schematic. There has to be a supply pin. Either check the complete board schematic or pull up a datasheet on the chip from the internet. |
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