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Floppie209 / Amiga2000-remake

A recreation of the Amiga2000 motherboard using Sprint Layout
Creative Commons Zero v1.0 Universal
100 stars 22 forks source link

Zorro Instability #7

Open bit-image opened 2 years ago

bit-image commented 2 years ago

I have built 3 of these boards, 2 work perfectly. However, a third board seems to have issues with zorro slots, specifically I am testing with a known good A2052 and with my first buster chip, all but the slot 1 pass the Amiga Test Kit memory test. With another Buster chip, every slot fails the Amiga Test Kit memory test. However, both buster chips work great in my other amiga boards. Anything I can check to get this working? All other memory tests pass including TF536 installed in the CPU SLOT. Zorro slots seem display errors weather I have the 68000 CPU installed or the TF536. Thanks for the help

bit-image commented 2 years ago

IMG_20220503_151246

bit-image commented 2 years ago

Troubleshooting further, seems like this could be a noise related issue. When I ground the stock amiga power supply to the motherboard, the screen noise is greatly reduced and the memory tested passes on all but the first zorro slot. My first 2 builds where using the black/copper board and this latest build with issues is the green/tin based Remake board. Both the black and green boards are rev 1.8.5. Is the green board somehow less tolerant of noise?

rhaamo commented 2 years ago

soldermask color shouldn't have an impact on the ground plane and pins, are both black and green coming from the same gerbers ?

if only the first zorro slot has issues, tries looking if there is no issues with the traces on the PCB, that would be the main culprit especially the GND pins.

bit-image commented 2 years ago

After mounting the board in a A2000 case, I get some different behavior, SLOT 1 is working well now, however the other slots dont even detect the ram card. I toned out all of the connections and find no issues. This is very hard to pinpoint, any other suggestions on how to get the other four slots to recognize the ram card? Thanks

bit-image commented 2 years ago

So I think I may have figured out the issue, the problem went away when I installed the bottom shield. It would seem that my issues are the result of noise / feedback ? However, the other 2 boards that I had built previously did not need the bottom shield to be in place in order for the slots to function.