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Mr. Ksoft

StarMax 4000 only boots via CUDA reset button?

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I recently picked up a Motorola StarMax 4000/160 DT.  Seems to be in decent cosmetic shape, no obvious damage on the board, but it doesn't power up via the power button or the keyboard soft power.  Strangely it powers up immediately without pressing anything if plugged in after being unplugged for a while (a day or so?).  The power button will turn it off but then not back on.  The only reliable way to get it to fire up is to press the CUDA reset button, which turns it on every single time.  (But that has the side effect of requiring the case to be open, and it wipes the PRAM).  The system works completely fine once it's on.

 

Of course first thing with these Tanzania boards is to replace the battery -- I have done so (fabricated my own 4.5V battery using a 3xAA battery holder) but no difference.  Multimeter confirms that my battery setup is putting out 4.5V, so I am fairly certain it was put together properly.

 

My best guess is that there is some kind of issue with the soft power circuit but I am not really sure where to start with troubleshooting (possibly checking that the board is actually getting the battery voltage).  Anyone have experience with the Tanzania board that might know something I don't?

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I've never tried booting my 4400 with the CUDA button. That's interesting.

Just a crazy thought, did you try manually jumping the power switch terminals? It could be a mechanical fault with the switch perhaps, if it still turns it off.
image.png.c088ec3ddc9e7f0e290b9e270d1dc1d8.png

Edited by jessenator

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I just tried that but it doesn't seem to work.  I wonder if something elsewhere in the system is keeping it "held" or something.

 

Also, an aside, but I can't get the damn thing to boot any CDs whatsoever.  The internal drive should be bootable, but isn't, and external SCSI isn't doing the job either.  Having an OS on this would be really helpful!

 

Edit:. Ok, apparently I was just really bad at picking OS discs. Retail 7.6.1 and 8.1 don't work but the Apple System Recovery 1 disc boots... So that is fine.  Still can't power it on aside from the CUDA button though.

Edited by Mr. Ksoft
answered my own question

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The 4400-specific disc images of 7.5.3 (the system restore disc) on Macintosh garden worked for me as well. These boards need a specific system enabler that not many discs had. Even the retail 7.6 disc wouldn't work for me.

 

I wonder, could there be a cold solder joint on the switch's underside?

Edited by jessenator

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I checked continuity across the board... So it seems the power switch flows through the CUDA reset button and something around there is controlling the soft power.  There's also good continuity from the soft power connector on the PSU to the CUDA button.  Probing the contacts around the button while plugged in seemed to trigger it to reset the CUDA and boot.  I did try manually jumping the power supply via the soft power connector, which does fire up the power but no boot or chime, probably cause I bypassed the CUDA.  I suppose I could try to reflow everything and see what happens.  A schematic would help me get further but I suspect there isn't one out there.  I couldn't find one.

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I'd be interested in a Tanzania schematic as well, but for different reasons :) hope you get things sorted out.

 

It seems that Adreas Kann has/had some of them… I haven't tried the email on this (archived) site, but could be worth a shot: https://museo.freaknet.org/gallery/apple/stuff/mac/andreas.kann/schemat.html

 

Well, that solves that… I guess if anyone knows him or can get ahold of him that would be cool.

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Edited by jessenator
revelation

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I had a similar problem on my StarMax 3000 where after sitting for a long time it only powered on once then seemed to be dead. Had to use the motherboard reset button a few times but since then it seems to power up normally each time I try. I'm also running it without a battery.

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I did some investigating and reflowed some suspect pins but no good.  Still only boots from the button.  What's bothering me though is the fact that I can trigger the CUDA reset by simply probing the pins on the button-- just touching the pins on the sides cause it to reset and boot (not a normal boot, the clock and everything still get reset).  Not completing the circuit with the multimeter... Heck, the multimeter wasn't even on, so not sending a voltage through it either!  Might this be a hint as to what is going on?

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