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IIci dead Nubus slots

Posted by: beachycove on 2021-01-31 05:57:06

I have posted a couple of times on here about my IIci with dead Nubus slots. I am downsizing and wondering what to do with the unit, and came across this on Reddit:

Anyone here seen this problem and found this the solution? Two small (and inexpensive) components near the Nubus slots are said to be the problem, with one of them in particular being susceptible to capacitor leakage because of its proximity to a 47µF / 16v cap, and we know what those can look like after 30 or 40 years of nights out on the town.

I am wondering whether to try one more heave in fixing this thing, or to part it out. The strange thing about it is that the machine appears to work perfectly otherwise. It just has no Nubus slots.

Posted by: MrFahrenheit on 2021-01-31 12:42:54

If you have the ability I would try and do the fix to see if it resolved the issues. I also have a IIci without working NUBUS slots which I purchased on this forum (knowing that they weren’t working). It’s better to try than passing it along and someone else just trashing the machine as a result. There are fewer and fewer of these that work in 2021.

If it works for you I’d love to hear.

Posted by: James1095 on 2022-12-02 13:12:37

Did anyone ever find a solution to this? I have two IIci's here with dead NuBus slots. I've recapped both of them, boards are clean without any serious damage. On one I replaced a 74ALS240 IC near the slots based on a suggestion but that made no difference. I have a pretty good understanding of PC ISA slots but NuBus is pretty foreign to me.

Posted by: volvo242gt on 2022-12-02 15:50:27

^Welcome back, btw... Yes, it's annoying that they're doing it... To those who aren't aware, one of the two machines James mentioned is the one I own...

Here's the thread talking about the 74ALS240 chip. It is on TinkerDifferent, but...

Problem with IIci and NuBus cards (Solved!)

Hello, testing an Ethernet Card that works on my IIsi and not in my IIci, it seems that I could have a problem with the NuBus slots. I found this: The Cap next to this IC did leak and it was replaced, but I didn't see until now evident damages in this chip. Did you have similar experiences?

tinkerdifferent.com

Posted by: Jockelill on 2022-12-23 11:05:56

Did anyone ever find a solution to this? I have two IIci's here with dead NuBus slots. I've recapped both of them, boards are clean without any serious damage. On one I replaced a 74ALS240 IC near the slots based on a suggestion but that made no difference. I have a pretty good understanding of PC ISA slots but NuBus is pretty foreign to me.

I had same problem and also replaced same chip, but without success at first. Then I realized that one pin is taking ground from the other side of the board and that via was broken. So a small bodge to a nearby ground solved the issue. I’ll try to post a picture.

Posted by: Jockelill on 2022-12-23 11:08:45

Check that this pin has ground.

Posted by: volvo242gt on 2023-02-08 18:41:22

That probably is what's causing my old board and the one that James has from his other friend's machine to not work. I wound up picking up another board with less cap goo damage, which has working Nubus slots, as well as a properly working Soft Power circuit.

Shown running video through a RasterOps video card I picked up a couple months ago.