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codepoet

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  1. codepoet

    NeXTStation Video Problem

    Just to close the loop, this was ultimately resolved with a New Old Stock logic board. Someday I'll completely re-cap the original board, just to see if that fixes the problem. NextStation now running great with an external SCSI CD-ROM and an internal SCSI2SD upgrade.
  2. codepoet

    NeXTStation Video Problem

    Was able to rule out the monitor using a very hacky hack to get some signal directly to a separate VGA. I didn't know how to deal with the grayscale, so I just sent it to green -- and you can see the same pattern shown. So its something on the logic board. I guess I'll proceed with ordering some caps, and see if that fixes anything (but I doubt it)
  3. codepoet

    NeXTStation Video Problem

    Thanks, cross-posted there. There doesn't seem to be nearly as much experience/expertise on Steve Jobs' "other" computers, so I'm casting as wide a net as I can for help!
  4. codepoet

    NeXTStation Video Problem

    Picked up a NeXTSTation with matching monitor, keyboard and mouse this weekend -- only $250 complete. Seller reported that it worked last time he used it but that it was showing "diagonal lines" when he tested before the sale. I got it home, checked the logic board and clock battery, then fired it up. This is what I got. Image is stationary and stable...just useless. Someone in a FB group suggested RAM, so I cleaned it up with contact cleaner and re-seated half (a full set of 4), then tried the other half. I noticed some white gunk around the RAM slots, but no obvious cap leakage. I do plan to re-cap, but I thought I'd check for signs of life after a bath (a trick that works on Color Classic logic boards that leak.) After thoroughly drying I re-assembled and powered back up -- no change. Same image on the screen. Finally I tried booting without RAM...same thing. It seems like all of that should at least have changed the symptoms if the problem was on the logic board. Now I'm starting to wonder if the issue is in the monitor. Anyone have any ideas?
  5. codepoet

    Mac Plus Display Problems

    The connector on the analog board is gone -- solder points cleaned bare. I think that's the female end? The end on the wires is still there, just nothing to plug into!
  6. codepoet

    Mac Plus Display Problems

    There's a lot of conflicting advice online about discharging -- everything from "don't do it" to "do it or you'll die." I have a copy of Dead Mac Scrolls, but not Pina's full guide. I went middle-of-the-road and set up my discharging kit, but didn't include the resistor -- since many forums suggested any arc would just hop over any resistance. I've probably used this setup 2 dozen times without issue: I only discharge if I'm going to be working near the high voltage gear...which is most of the time, since that's where most problems seem to be. On this occasion, the discharge was fairly shortly after the unit was powered on, and the spark was an enthusiastic one. Clearly I should have had the resistor in place. I've order a replacement part from Mouser.com for the donor Mac (which is missing other parts as well*) as well as a resistor to add to my gear. *Speaking of the donor Mac, its also missing the yoke connector -- apparently donated to some other project before I inherited it. Does anyone know where I can find such a connector?
  7. codepoet

    Macintosh SE video problem

    Replace the chip shown in this picture. Also see my similar, but worse, situation which was resolved thanks to the above advice from a kind stranger on Facebook:
  8. codepoet

    Mac Plus Display Problems

    This was caused by damaged to a chip on the analog board, caused by discharging the CRT to the frame. My discharge cable did not include a resistor, because I read somewhere they wouldn't work. Turns out leaving it out is a bad idea. The damaged chip was a Motorola SN74LS38NDS, which I replaced with the same number but from a different brand, from a spare Plus that was more dead. The picture is now sharp and clear, without any lines. If an expert is someone who has made all the mistakes, I'm well on my way to becoming an expert :-)
  9. codepoet

    Mac Plus Display Problems

    Thanks for responding, I concur that all the caps look good. The video problem looks like an extreme version of this guy's SE issues, except he gets a faded picture, and I get none. I replaced the logic board, to rule out anything on that side, and got the same result. Its got to be something on the analog board...
  10. codepoet

    Mac Plus Display Problems

    I've acquired a plus that would make a happy boot chime, but show no video -- although occasionally the screen would flicker if the case was smacked. Following Dead Mac Scrolls, I re-flowed the solder on J4, and following a tip found elsewhere online, I re-flowed J1 as well. Now it comes up to only this. Adjusting contrast does not show any other pictures. The Mac boots happily from a FloppyEmu, but the screen doesn't change at all. Reducing voltage dims the image, but does not change it -- nor do any of the other screen adjustments cause an image to be visible. Any advice? I'm obviously going to re-cap, but I want to make sure this thing is a survivor before I lay down the cash for the caps.
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