| Arcade Collecting > Restorations & repair |
| NPs Paperboy Restoration |
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| 2600:
--- Quote from: Neverending Project on September 15, 2008, 03:16:09 pm --- 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. --- End quote --- 6116 have a GND and VCC. Pin 24 is VCC and Pin 12 GND. Sometimes when you draw schematics, you don't actually draw the power connections, it's just assumed. What would really be helpful for you is to find someone else with a System 2 setup to test your boards? Just to make sure the board is at fault. |
| Neverending Project:
--- Quote from: TheShanMan on September 15, 2008, 03:32:18 pm ---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. --- End quote --- Good to know. Since some of the ICs in the schematics listed +5V, I assumed they all would. The funny thing is I tried to google the schematic for the chip, only to return page after page of crappy sites selling datasheets. But when I just checked again using the term "6116 datasheet" instead of "6116 pinout" or "6116 schematic" it was the first link. --- Quote from: 2600 on September 15, 2008, 03:33:47 pm ---6116 have a GND and VCC. Pin 24 is VCC and Pin 12 GND. Sometimes when you draw schematics, you don't actually draw the power connections, it's just assumed. What would really be helpful for you is to find someone else with a System 2 setup to test your boards? Just to make sure the board is at fault. --- End quote --- Excellent, thanks for the info. I will check these voltages. And I will keep my eye out for a System 2 around me - it would be helpful indeed. |
| channelmaniac:
http://www.datasheetarchive.com is your best friend for datasheets. ;) |
| Neverending Project:
All the 6116s have 4.98V between pins 12 and 24. I guess next up will be to check the voltage at each ROM chip. I suppose one could still be bad, though. Is it even possible to replace only one ROM chip, assuming I could find a replacement or figure out how to burn a new one? Hmm, come to think of it, how would I find out what would need to be burned on each chip? The only replacement Paperboy boards I have seen are in the neighborhood of $200, and it is not a neighborhood I was hoping to take this cab to. |
| RetroACTIVE:
--- Quote from: Neverending Project on September 16, 2008, 10:53:28 am ---All the 6116s have 4.98V between pins 12 and 24. I guess next up will be to check the voltage at each ROM chip. I suppose one could still be bad, though. Is it even possible to replace only one ROM chip, assuming I could find a replacement or figure out how to burn a new one? Hmm, come to think of it, how would I find out what would need to be burned on each chip? The only replacement Paperboy boards I have seen are in the neighborhood of $200, and it is not a neighborhood I was hoping to take this cab to. --- End quote --- If your RAM chips are socketed...pop them out and move them around... see if the defect changes. :cheers: |
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