Mac IIfx boots but no video

[drykid]

Hi,

My first post here Have just pulled out of storage my IIfx that was working fine when it went into storage a few years ago. The motherboard is very clean on it, no battery leaks or exploding caps (unlike the mb it replaced which *did* have a cap explode and was a horrible mess ) I just put in two brand new 3.6 volt batteries as the old ones were dead. Currently it seems to boot ok in the sense that the hard drive spins up and the noises it makes are consistent with the OS booting (see youtube video below.) There is no start-up chime but sometimes I get a single beep instead. Currently it has the HDD and one of the floppies connected, there's a pin missing on the mb connector for the second floppy so I assume that connecting that is likely to cause additional issues and therefore I've left it unplugged.

Things I've tried:
- swapping in a spare power supply from a Mac IIx that I have here (no difference to outcome)
- swapping in a different nubus video card (also from the Mac IIx) (again no difference)
- swapping the nubus slot for the video card (no difference.) It's worth noting that I also have a nubus network card in it as well and the green light on the card comes on when put in the same slots that the nubus video card does nothing in.
- swapping out RAM; it originally had 20 MB (4x 1MB in one bank and 4x4 MB in another) so I've tried putting both sets in bank A in turn and leaving bank B empty. But regardless of whether I use the 4MB set or the 16MB set the outcome is the same.
- re-seating the ROM card.

One thing to note; on one solitary occasion I did get the startup chime and it booted through to the OS cleanly with video. I have never been able to repeat this; obviously I just got lucky on that one occasion. But if nothing else it proves that the PC monitor and Lacie Mac-to-VGA adapter that I'm using are compatible (although I did try a second Mac-to-VGA adapter and a couple of different PC monitors anyway out of sheer desperation but no difference.)

Also worth noting is that although the hard drive noises suggest it is booting ok you can't shut it down by the power switch on the back, only start it. Interestingly this was also the case on the one time I managed to get it to boot with video.

So I'm beginning to think it's the motherboard itself that is the issue although I've no idea where to look next... Any thoughts?

Here's the video (sound is a bit quiet so you may have to turn it up to hear the HDD):

 

[SuperSVGA]

I'm not sure if I'm missing it, but it doesn't sound like there's enough hard drive activity there for booting. To me it sounded more like just the drive's startup routine, likely reading some data off the drive or performing a test.
Have you tried putting in a floppy disk to see if it makes any attempt to boot off that?

That you've had a startup chime in the past but not now makes me think that the computer isn't even executing the rom.


I'm jealous of your Indigo2 vertical stands, I need to get those for mine.

 

[LaPorta]

There’s a likelihood of the power on circuit not working properly if you can’t shut it off via the power button. There’s threads here on the forum dealing with it if you search for them.

 

[drykid]

I'm not sure if I'm missing it, but it doesn't sound like there's enough hard drive activity there for booting. To me it sounded more like just the drive's startup routine, likely reading some data off the drive or performing a test.
Have you tried putting in a floppy disk to see if it makes any attempt to boot off that?

That you've had a startup chime in the past but not now makes me think that the computer isn't even executing the rom.

Yeah you could be right about that, it sounded like it was doing something but I agree that it doesn't last for very long. But I did also try it with just the floppy drive connected (but no floppy in it) on the basis that that might be enough to get the drive-with-a-flashing-question-mark icon to appear if nothing else, but unfortunately it still didn't produce video output. I suppose I could re-try it with an actual bootable System disc but the problem will be making one first; the only bootable 68k Mac I have here at the moment is a Quadra 700, will that do the trick? I forget now what the compatibility is between various different Mac floppy drive types.

I'm jealous of your Indigo2 vertical stands, I need to get those for mine.

They are cool, and it takes it up a lot less space that way. I used to think of it as a gigantic Playstation 2 (back when Playstation 2's were a novelty.) Unfortunately the Indigo2 isn't working properly either (desktop corruption; I need to take it apart and check that everything is seated properly. If not then it needs a new graphics card set, and that would cost hundreds *sigh*)

 

[SuperSVGA]

I suppose I could re-try it with an actual bootable System disc but the problem will be making one first; the only bootable 68k Mac I have here at the moment is a Quadra 700, will that do the trick? I forget now what the compatibility is between various different Mac floppy drive types.

You could at the very least try it with a blank, as far as I know the drive won't attempt to read just by receiving power, the computer has to actually take the action.
The IIfx has the SWIM, so both 1.44MB disks and 800K disks should work fine, and it should accept both System 6 and System 7.

They are cool, and it takes it up a lot less space that way. I used to think of it as a gigantic Playstation 2 (back when Playstation 2's were a novelty.) Unfortunately the Indigo2 isn't working properly either (desktop corruption; I need to take it apart and check that everything is seated properly. If not then it needs a new graphics card set, and that would cost hundreds *sigh*)

I still need to test mine once I get time one of these days. Unfortunately whoever went "personal data bad" and took the hard drive out also took out the caddy and interposer. That and I need to find compatible monitor and adapter.

 

[drykid]

You could at the very least try it with a blank, as far as I know the drive won't attempt to read just by receiving power, the computer has to actually take the action.
The IIfx has the SWIM, so both 1.44MB disks and 800K disks should work fine, and it should accept both System 6 and System 7.

OK so I disconnected the HDD and tried connecting each floppy drive in turn (don't want to connect both at once due to the damaged mb connector previously mentioned) and putting a formatted Mac floppy (not System itself) in each one. It's hard to say if it's reading them properly but there's a bit of noise when each one goes in. But still no video. It's beginning to look like the startup circuitry on the MB is the issue I think.

I still need to test mine once I get time one of these days. Unfortunately whoever went "personal data bad" and took the hard drive out also took out the caddy and interposer. That and I need to find compatible monitor and adapter.

That's a pain, mine had a failed HDD when I got it but everything was still in place so it was just a case of buying a similar drive, swapping it over and doing a clean install from a media set.

As for a video adapter I just use the one in the attached photo; wish I could tell you who made it but there's no markings of any kind on it, not even a number. But it seems to work with a few of my LCDs. I have about half-a-dozen around as with this kind of stuff it's always good to have something else to try when one doesn't work (and old 17" 4:3 LCDs cost next-to-nothing these days.)

 

[joshc]

Bad ROM socket I think - hold the ROM SIMM in place tightly with your hand while you start the machine. Any difference? Rubber bands or hot glue can be used to help hold it firmly in the socket. Whenever my IIfx won’t start properly, I check and reseat the ROM.

 

[drykid]

Bad ROM socket I think - hold the ROM SIMM in place tightly with your hand while you start the machine. Any difference? Rubber bands or hot glue can be used to help hold it firmly in the socket. Whenever my IIfx won’t start properly, I check and reseat the ROM.

Thanks, I did originally take it out and completely re-seat it, but I've now also tried doing exactly what you said and pressing down on it while booting but no difference unfortunately. For what it's worth that SIMM feels very solidly held in place anyway by the two retaining clips on either side, so it doesn't feel like pressing down on it is actually physically changing anything anyway.

 

[joshc]

Odd then. Are any chips on the logic board getting warm? Got another ROM SIMM you can try? Also worth reseating and trying different RAM.

 

[drykid]

Odd then. Are any chips on the logic board getting warm? Got another ROM SIMM you can try? Also worth reseating and trying different RAM.

Funnily enough since I last wrote I tried a different ROM SIMM as I'd forgotten I had two of them, but no difference. Also tried reseating the RAM but again no difference. Will try looking for chips getting warm though.