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I’m trying to resurrect a Craigslist Amiga A1000. After replacing Paula it now boots. Several basics still missing (RF shields, screws, port covers, etc.) but essential electronics are okay.

However, I would like to add the 256 KB RAM expansion but I haven't been able to locate one. I have been able to recreate much of the schematic for much of the A1050 (thanks to Raffzahn for excellent information), but not sure of 2 things - 1) capacitors, and 2) the black blob:

  1. My guess is 8 the capacitors are 220 nF but don't know about the other one (c9?). I think they are connected between 5 V and GND?
  2. The blob maybe a 39 Ω resistor pack to buffer the address lines? Or?

Any insights/thoughts/facts appreciated.

Front of board: Front of board

Back of board: Back of board Source: http://amiga.resource.cx/exp/a1050

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  • Have you measured it? – OmarL May 19 at 8:58
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    The capacitors are probably decoupling capacitors, right? So do you really need to replace them like for like? – OmarL May 19 at 9:00
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    Can you post the schematics that you've created? – Alex Hajnal May 19 at 10:36
  • Based on the photos I've seen I'd concur with your take on things. The caps all appear the same and wired the same (VCC to GND). One photo I saw had the label 224 on one of them, i.e. 220nF. The "black blob" is probably 8×39Ω 5% resistors wired straight across (pin 1-16, 2-15, 3-14, 4-13, 5-12, 6-11, 7-10, 8-9). – Alex Hajnal May 19 at 12:23
  • @OmarL I think TOD is trying to recreate the board without having physical access to an original board. – Alex Hajnal May 19 at 12:32

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