IIx died, possible bad PSU?

[Fred1212]

Well done

 

[mjreilly]

Have you seen this thread? I ended up gutting my Iicx power supply and replacing it with an SFX power supply innards. Works great. I didn't do the soft power circuit, just removed the monitor power receptacle and mounted the power supply's switch there.

Stealth Macintosh IIcx/IIvx style SFX PSU rebuild

Hello, I've been asked to post this here on IRC so there it is. A lot of PSUs from this era are bad quality and difficult to repair (if possible at all). One of the worsts is the Astec AA15830 (Apple P/ 699-0392) One of the solution is to use the excellent adapter board by @blusnowkitty and...

68kmla.org

 

[Kipio]

That's good advice, and I have seen that thread before! Unfortunately I don't think a standard ATX PSU will fit in the IIx, because it has a longer but quite a bit narrower power supply than the IIci/IIcx. Hence my decision to go with the TFX power supply. I am going to be using soft power... in fact, it is already installed and working in the photo I posted earlier. So really my primary remaining challenge is how to physically fit the TFX PSU into the old case in a way that works properly. I think I have a handle on how to do it; it is mostly a matter of finding the time to get it done.

I'm going to try to take pictures as I go along so I can post either here or somewhere else publicly accessible to document for posterity.

 

[Juror22]

Glad you got it working! One of the brilliant, but maybe overlooked items in that picture is how you placed your board on the bottom of your inverted case as an ersatz bench. Elevated, non-conductive, no worrying about putting the board in correctly each time - nice!
Great work with the PSU also!

 

[mjreilly]

That's good advice, and I have seen that thread before! Unfortunately I don't think a standard ATX PSU will fit in the IIx, because it has a longer but quite a bit narrower power supply than the IIci/IIcx. Hence my decision to go with the TFX power supply. I am going to be using soft power... in fact, it is already installed and working in the photo I posted earlier. So really my primary remaining challenge is how to physically fit the TFX PSU into the old case in a way that works properly. I think I have a handle on how to do it; it is mostly a matter of finding the time to get it done.

I'm going to try to take pictures as I go along so I can post either here or somewhere else publicly accessible to document for posterity.

Ah, got it, didn't realize the difference in size. I should add the soft power and post some pics too.

 

[Kipio]

It seems as though I celebrated too soon. I ran the system multiple times, and it was booted for at least an hour total with no issues. Then, I disconnected the motherboard in order to hot glue down my bodge wires, hooked it back up, and now this is happening consistently. It starts at the boot process and doesn't stop no matter what I do.

I went over my work again on the motherboard to make sure I didn't screw anything up while gluing down my bodge wires. I reseated the RAM and ROM SIMMs. I tried different Nubus cards and different slots. I have tried wiggling things, tapping on things, and gently flexing the board. I confirmed the monitor works fine with a IIcx. I verified that my (new) PSU is outputting proper voltages on different rails. But no matter what I do, this pattern always seems to be there. Has anyone encountered this sort of thing before? Any advice?

PS. I'm going to be at VCFMW this weekend, so if you are one of the many who helped me with this project and are going to be there, DM me and we'll meet up and I'll buy you a coke/beer/cheeseburger.

 

[cheesestraws]

Does it finish booting "behind" the weird bars?

 

[Kipio]

Oh yes, I should have mentioned that. Other than the bars, it seems to boot up and behave normally. I haven't tested running applications, but I am able to fully boot, the mouse pointer works, I can select menus, etc., and then perform a full "soft" shutdown.

 

[dv-]

I know OP fixed their problem, but many years ago I had a IIx that doorstopped itself when the PRAM batteries died. Just want to put that out there in case somebody is googling this later.

 

[finkmac]

the batteries are integral part of the soft power circuit on big II machines. as far as I understand, the PSU doesn't provide a power trickle, the trickle comes from the PRAM batteries.