Hi!
A coworker got me an X68000 from Yahoo Auctions. Unfortunately, it only turned out later that the condition was marked "junk".
So I carefully turned it on. For a few seconds, it seemed fine (I didn't have a monitor attached), so I turned it off again. I noticed it smelled funny (hard to describe - I'd say a sour smell), so I turned it on again to see if it came out of the fan of the machine - and indeed it did. But on this second power on, after roughly 10 seconds, I got magic smoke. So I immediately turned it off and disassembled it, and sure thing, the PSU is dead. Also the battery has leaked.
I disassembled everything and cleaned up the leaked battery, checked the traces around the battery and couldn't find a dead one (I killed one trace while scrubbing it to see if it's still there, I already bridged it), but would not vouch for all traces still being 100% intact - I only couldn't find a dead one. I then attached an ATX power supply (and used an inverter for soft power), and it does turn on. I turned it on in a disassembled state, with just the mainboard, daughterboard and RGB module, and got no picture. After quite some fiddling (and even checking the 68000 CPU with an oscilloscope), I figured out that it seems that the CPU failed to talk with something on the bus, and got the idea to attach the riser card, and sure enough, I now got a picture. It's the common "System failure, please reboot" message, but it has a lot of noise in the background. When pressing reset, the noise goes away. When powering it off for only a short while and powering it on again, there is less noise (I attached pictures).
I already changed all caps (except a few on the RGB module that did not seem relevant - the entire RGB module doesn't seem all that relevant to the boot process), and the only thing that changed is that I now get a more stable picture that doesn't break up after 20 seconds (it stays for several minutes - haven't tried longer). I also tried pressing opt1 and opt2, as apparently that sometimes helps, but it made no change. I even did insert a floppy (albeit not one for an X68000, since I don't have any disks with software for it yet), but it did not even try to access it. I also noticed that when I am at this screen and press the NMI and reset button at the same time, the text fades out and I get a black screen. As in, with actual fade animation. Is this normal behavior?
Does anybody have ideas what I could try? Anything I should check? I'm out of ideas by now. I already looked at the serial port, and there's nothing. I guess I need some extra ROM for that in the unfitted ROM slots?
If you don’t do anything do you get to the insert disk screen?
No, only the screen above. I've never seen it output anything other than the pictures attached.
When you open the computer, on the floppy drive side and behind it is a small PcB for the external SCSI and floppy. Can you take a pic of the components on there and post here?
I've seen similar issues on various machines, and never could figure out what was wrong. I believe that generic error message comes up if anything goes wrong in the bootup chain, so the problem could be anything. It is a hardware problem though, and might be as simple as a broken trace, or as complex as a cutom IC having failed.
@leonk: I'm not sure what you mean exactly? The side with the floppy drives had no PCB - it only had space for the HD, the floppy drives and some connectors. Yes, the connectors are technically on a PCB, but there are zero components on it. Is that what you mean?
@kamiboy: Yeah, that's what I figured from browsing the forum already. However, there's two questions: Where is this noise on the video output on initial power off coming from and why does it go away when I press reset? That sounds like the initial initialization is going wrong, while the initialization triggered by the reset button works. And the other is: Is there any way to debug what it is?
The noise is prolly caused by VRAM being corrupted.
the bottom pcb of the computer has 2 ribbon cables coming up. they both connect to a circuit board located behind the floppy drives. I believe one of the cables is multi color. please post pics of that circuit board.
does it look like this or do you have missing components? like the blue resistor pack?
http://i.imgur.com/7NZqY81.jpg
@kamiboy: But then the garbage would stay after a reset, wouldn't it? And it would get new corruption over time? But after pressing reset just once, no noise comes back - the picture is clean post-reset.
@leonk: I don't have the board with me right now (I left it at my hacker space over night), but I'm quite confident that it had absolutely no components, which is why I didn't even bother attaching it for testing.
Here's the PCB without any components.
And here's the entire setup for testing.
Interesting.
So. this is the HD version. I wonder if this related to an issue I recently documented on the wiki. The SCSI is hanging because it’s not terminated.
https://gamesx.com/wiki/doku.php?id=x68000:black_screen_on_xvi_hd_and_potentially_other_hd_computers