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NE555

6502
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Everything posted by NE555

  1. NE555

    another simasimac

    @Bolle Address lines 23 to 31 where do they go from the CPU? I traced 25-31 to UJ6
  2. NE555

    another simasimac

    I recapped the SE/30 logic board. then upon start up , there is no bong, no error chime. just a Simasimac screen. I have been trying to trace things out and found a whole bunch of vias without solder in them. Been trying to fill them with solder and a piece of wire. So far the Simasimac persists. I keep finding more and more empty vias. I am not sure if what I am doing is actually helping in any way. All the rails seem to get the proper voltages. LS166 has been replaced already. what's next?
  3. NE555

    another simasimac

    I had some partial success. I found a dateline that has been OL and when I traced it out I found out that it ended up in a via by C12. I was able to reconnect that Data line back to the CPU. and now I get some distorted boot chime and a variation of Simasimac. I guess I'll have to probe the address lines next. Thank you for following up
  4. NE555

    another simasimac

    all data lines from the floating processor to ROM are good. My CPU is not socketed
  5. NE555

    another simasimac

    It can't be more boring than some of the videos that are on youtube at the moment. I can't find any traces that are OL. But I am getting the feeling that even if a trace might not be bad It might have a resistance that makes it useless? As I said I would like to see a video like this just to be able to compare to a baseline. Maybe someone testing the board with an oscilloscope even. check between CPU and anything else sounds extremely generic. How many have actually fixed a Simasimac SE/30? And I don't mean one that just needed C6 and C7 replaced
  6. NE555

    another simasimac

    I wished someone would make a youtube video of that process
  7. NE555

    another simasimac

    thank you for that info.
  8. NE555

    SE/30 with graphics issue

    Oh ok , that makes sense then. I thought you meant it booted regardless of no RAM
  9. When I turn on the board I get a fast error chime, no video. When I install a ROM sim I will get a green striped screen. Jumper is in . All memory populated or 4 RAM populated makes no difference. swapped for other RAM it makes no difference, either. The Power up circuit seems fine. So what is next to check out?
  10. SO yes Even without RAM I will get a fast chime. The green pattern comes up with a ROM in the socket and internal video and RAM. I didn't try a NUBUS video card. well I did. But I am not sure that card is actually good. I can take a high res picture, but there is nothing prominent. I even looked it over under the microscope About the ROM, I tried with an SE/30 ROM https://www.ebay.co.uk/itm/Apple-Mac-SE-30-ROM-64-Pin-SIMM-Macintosh-820-0241-02-630-4339-Vtg-SE30-/362591668923 The other is a toshiba ROM SIMM it has a number 7788A1. Not sure if that's a SE/30 simm
  11. NE555

    SE/30 with graphics issue

    Am I reading this correct? You said you got the Computer to boot without RAM? I didn't know that would work... Actually I'm pretty sure that wouldn't work. Hmmmm ...
  12. I used a couple of 512k ROM . They should boot or at least show a gray screen? I also tried the RAM of a good board. to the same effect. If the onboard ROM is bad then using a 512k Should do the trick or not? PSU is known to be good, too.
  13. No broken traces under or near the battery tray. I noticed that having the RAM in or not doesn't seem to make a difference. But taking the ROM jumper out causes the board to do nothing at all.
  14. there is no prominent damage from battery acid. But I'll look at the traces and vias in that area. thank you for the advise.
  15. NE555

    ewww

    This board shows the capacitor leakage really nicely thanks to being so dusty
  16. Here is a curious issue I am having. I turn on the IIci and the board gives a chime, then a gray boot screen but the corners are still there and then the death chime comes in. I can replace the RAM with different models and get different results. The NEC for instance give a different error than the Samsung for instance. If I put in a ROM and leave the jumper in place , I'll get just a gray screen. With the jumper removed (which is the correct way with a ROM installed), then I will get the death march almost instantly with a black screen. Due ti the fact that there is POST and the chime first, I like to think that I got a Memory SIMMS issue. But the placement of the ROM snd resulting error makes me think that there is maybe an issue with the ROM or ROM SIMM? What is you guy's thought on this?
  17. I removed the SIMM sockets and will be replacing them with new ones. BTW The memory SIMMS are always to be populated by entire banks of 4. So that was of no issue.
  18. thanks, that's probably good advise.
  19. I am leaning towards the RAM SIMMS as well. I have Single row SIMMS with the metal clips. I don't like them too much. I'll shop for double rows. So far I have scrubbed the pins with alcohol and baking soda. Then I have touched up the solder pins . It didn't make any changes.
  20. Does anyone have the logic board schematics for a Iici? I have the IIci start up circuit but I need them all.
  21. NE555

    ewww

    Yes
  22. All caps replaced, traces seem ok, replaced the speaker jack, but the issue is still there. Any thoughts? There is either no sound or sound with the external speaker plugged in.
  23. As per my first post, I replaced the speaker jack
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