Jump to content
Tempest

IIfx Won't boot

Recommended Posts

The Mac II had a variable speed fan.

 

The Mac II and IIx power supply a single speed fan. The IIfx has a variable speed.

That's contrary to Usenet posts which I have read regarding the subject.

 

Re: Mac II fan noise - an unauthorized solution - 17 Jul 1988 6:17 pm

 

Interesting... I'll have to look up a Mac II manual to check that. However, even the person that posted that says he's never heard it speed up or slow down.

 

Here's the info at Low End Mac for what it's worth:

http://lowendmac.com/ii/macintosh-iifx.html

Although appearing identical to the Mac II and IIx, the IIfx power supply has a variable speed fan to better control noise and cooling.

 

In the Apple service manual the II and IIx have a different part # than the IIfx... Power Supply 661-0375 (II, IIx) 661-0542 (IIfx).

Share this post


Link to post
Share on other sites
The trace on the top of the board on the left side that goes from the capacitor(?) at C45 to the spot below the second Nubus slot labeled FD15 (between zones N2 and K2) is completely burned out. It looks like it took a hit or something in the past. I'm not sure what this trace connects, but I'm guessing it's needed since it seems to come from the power supply.

I believe there may be a short circuit somewhere. It caused the trace to burn and also burned the power supply. So the next step is to test nearby capacitors to see if they are short circuited. Once you successfully find and remove the short circuit...

 

The easiest and fastest solution is to run a wire directly from the yellow wire on the power supply to the yellow wire of the hard drive power connector. This would effectively bridge the gap, wherever it may be (probably this burned trace), and cause the floppy to come to life as well.

 

For a permanent solution, you should try to repair the trace that is burned. You will need a soldering iron and a piece of wire. Follow the trace from the burned area until you reach a spot you can solder to. Then follow the trace in the opposite direction until you find another spot you can solder to. Then solder a wire connecting these two spots.

 

I highly recommend using a 30 gauge solid wire for this. If you strip the wire and it's lots of little strands, it will be more difficult to solder accurately. Solid copper 30 gauge wire can be purchased at RadioShack.

 

DO NOT bridge this gap or run any wires until you find the short though!

repair.jpg

Share this post


Link to post
Share on other sites

The easiest and fastest solution is to run a wire directly from the yellow wire on the power supply to the yellow wire of the hard drive power connector. This would effectively bridge the gap, wherever it may be (probably this burned trace), and cause the floppy to come to life as well.

 

That's actually not a bad idea... and probably the safest way to troubleshoot the problem if you choose to do so.

Share this post


Link to post
Share on other sites

How would I figure out where a possible short is?

 

Running a wire directly to the disk might solve the problem, but that's still a hack and not a fix (remember the HD wasn't spinning up either). Once I'm sure there's no short I might just try bridging the short with a wire and see what happens.

 

Tempest

Share this post


Link to post
Share on other sites
How would I figure out where a possible short is?

 

Running a wire directly to the disk might solve the problem, but that's still a hack and not a fix (remember the HD wasn't spinning up either). Once I'm sure there's no short I might just try bridging the short with a wire and see what happens.

 

Tempest

You can use a continuity tester. Most multimeters have this function, sometimes it's called a diode tester or uses any variety of weird symbols. It's usually the function that looks different. Touch the probes together and the readout should change.

 

To find a short, first test any electrolytic capacitors. Touch a probe to each wire coming out of the capacitor and see if the tester shows a short. Especially test capacitors near the burned trace. If you find it, replace the capacitor, then patch the burned trace. It sometimes sounds easier than it is, and it's not necessarily a cap, but you might get lucky and find it right away. We can certainly arrange to send it to me for fixing as well. I live in Minnesota so we're not that far away.

Share this post


Link to post
Share on other sites

Tempest and I have worked a deal for me to repair his IIfx logic board. I will chronicle the repair here when I receive it in the mail.

 

"Dennis Nedry" / Ben

Share this post


Link to post
Share on other sites

I received the board and other goodies. Here is what happened since then:

 

A. Checked for a short from +12 to GND or any other rail. I found some suspiciously low resistances. (i.e. a short = 0 resistance.)

 

B. Removed all RAM and ROM SIMMs.

 

C. Removed all electrolytic caps from the logic board, except for C42 which I can't readily replace, 1,000uF 10V. This cap has not leaked and does not test as shorted.

 

D. Thoroughly cleaned the board and blew it out to remove most of the water, then let it dry on a fan.

 

E. Replaced all the caps I removed with brand new ones. 5 electrolytics and 2 tantalums were used. 1 axial cap was replaced with a radial unfortunately, but it turned out very well.

 

F. Patched the burned trace.

 

G. Checked for short circuits again, found none. That's a very good sign.

 

H. Verified a hard drive would spin when attached to the internal power connector. This is a faulty hard drive however, so no booting took place.

 

I. Booted the Mac from a floppy successfully.

 

J. Booted from an external hard drive all the way into A/UX 3.0.1. Flawless and may I say VERY FAST.

 

K. Checked RAM, there is 8MB of RAM installed. These are 1MB SIMMs. Hang on to your other IIfx RAM, Tempest!

 

L. Done. I will be sending it back to you soon, Tempest.

Share this post


Link to post
Share on other sites
I have some 1,000uf 25 volt caps here, they were removed from a board, but that board was brand new and never used

I'm not exactly sure if it's worth it. The cap looks to be in perfect condition. I have a few similar caps as well but I'm not sure how good they are or how old they are.

Share this post


Link to post
Share on other sites

being that large its not going to be anything mission critical (big farads = low frequency filter, or a really half hearted fudge of a timer) I have just been cleaning and sorting through stuff preparing to let my wife know about the //c (shh) that I am going to rebuild this summer once we get some good retrObright weather

Share this post


Link to post
Share on other sites

Well I finally got the IIfx working. Turns out both of my SuperDrives are bad (not sure if they're fixable) but I had a spare working HD so I was able to get it to boot into System 6.0.8. I still can't get that SuperMac video card to reset itself for my new monitor, but I found I also have a RasterOps 8XL card which seemed to like my monitor just fine. Unfortunately I only have 8MB of memory as 16 of the memory sticks I have are 1MB sticks and the other 4 appear to be bad (the Mac won't boot with them in), but I assume they're also 1MB sticks.

 

Tempest

Share this post


Link to post
Share on other sites
and the other 4 appear to be bad (the Mac won't boot with them in), but I assume they're also 1MB sticks.

If the RAM is bad, the Mac should make a death chime instead of, or in addition to, the normal startup sound.

 

Bad RAM can be caused by:

  • Dirty connectors (clean with an eraser)
  • Mismatched RAM, maybe some SIMMs are different sizes than others
  • One or more SIMMs is bad

 

Did you find your hard drive power connector?

Share this post


Link to post
Share on other sites

Yes I found it.

 

When I put the 'bad' set of RAM in I get a normal chime but then nothing happens (the OS never loads). When I stick a good set in the other bank I get the chimes of death sound.

 

Tempest

Share this post


Link to post
Share on other sites

If these SIMMs are all identical, then at least 1 of the 4 is dirty or bad. Check to see if the numbers on the actual chips match from SIMM to SIMM. If they're different at all, that could be the problem.

 

8MB actually will still get you a long way with a Mac IIfx. Apps and Mac OS from back then are very conservative with RAM.

Share this post


Link to post
Share on other sites

just something to try ...scuffing the contacts lightly with some fine grit steel wool, works better than pencil eraser on mismatched "settled in" parts, but its dust is highly conductive

 

a small stiff brush submerged with the board in a cleaning solution is a sure fire way to be sure, but a fine point pinch of wool carefully applied and some compressed air can be effective with care

Share this post


Link to post
Share on other sites

Ok I'll try the steel wool. I tried a pencil eraser but it didn't seem to help. The contacts on one seem to be a bit corroded or damaged so that's probably the issue.

 

Tempest

Share this post


Link to post
Share on other sites

Instead of starting a new thread I'll tack onto this one.

 

I'm trying to get my "new" IIfx working here. Initially it didn't power on. I added in two batteries and that got it to boot, but the hard drive didn't spin up. I tried to boot from a floppy and it started to load, a SuperMac logo appeared and the floppy was ejected.

 

Now it chimes, the sound seems to initialise but that's as far as it goes. The floppy isn't powering up any more and there's nothing onscreen.

 

I pulled one of the SuperMac cards to try to ID it. I also connected up the hard disk from my LC III (just the power cable, not the SCSI) to check that the PSU was working OK. The LC III disk spun up fine so the fault seems to be with the IIfx hard disk. I also tried to hook up the LC III's floppy to check if it would boot any further (perhaps the IIfx's one is faulty). It didn't power up. So somewhere along the way, one of these things I tried seems to have messed things up. Has anyone any ideas?

 

Updates:

 

I pulled the second SuperMac card and the drives and booted to a grey screen. Put the drives back and I still boot to a grey screen. If I pull the power cable from the hard drive it boots to the grey screen with the SuperMac logo in the bottom right corner. The floppy isn't powering up at all.

 

Both cards installed and no drives gets me to a grey screen. Attaching the LC III floppy yields the same, but the drive doesn't try to read or boot the inserted floppy. Reconnecting the hard drive's scsi cable (but not power) and the floppy gets me the grey screen with the SuperMac logo, but no movement out of the floppy drive. Reconnecting the hard drive's power cable as well, gets me the grey screen without the SuperMac logo.

 

If I lift up the floppy disk inside the drive, I can hear heads/motor at work. So it is getting power at least. Could I have damaged the floppy connector on the IIfx logic board in some way by hooking up the floppy from the LC III?

 

I tried the IIfx floppy on the LC III and it "works" but floppies are unreadable and when it tried to format it failed verification. So I guess it's gonna need a look at.

Share this post


Link to post
Share on other sites

Still no progress. I can't get it to boot beyond these grey screens. I've tried the internal disk from my 7500 and an external SCSI (as apparently you don't need the black terminator for newer drives).

 

The first time I powered it on after putting in the batteries it got to the "missing system" blinking icon. Never saw it again.

Share this post


Link to post
Share on other sites
Still no progress. I can't get it to boot beyond these grey screens. I've tried the internal disk from my 7500 and an external SCSI (as apparently you don't need the black terminator for newer drives).

 

The first time I powered it on after putting in the batteries it got to the "missing system" blinking icon. Never saw it again.

 

Do you have a voltmeter? I would start by measuring the output of the power supply and determine if the 5V is at 5V and the 12V is at 12V, etc.

 

I'm not sure the LCIII floppy will work in the IIfx. It shouldn't hurt anything to try, but using a manual inject floppy drive in a machine that expects an auto-inject drive is problematical. I think it requires a different cable, at the least.

Share this post


Link to post
Share on other sites

Unfortunately no. I'm not really equipped for this level of troubleshooting. I'm still at the swap-with-a-known-good-part stage.

 

I've stripped it down a bit now. Disconnected everything from the logic board except for the PSU connector as that's very tight. At a minimum, what should I need connected to at least get it to check for a system disk to boot from? ROM, one gfx card and a stick of RAM? What about the internal SCSI bus? The service manual says I need a special terminator if there is no drive attached. I've tried attaching two drives (Apple branded from my 7500 and a non-Apple Quantum from my LC III) and neither got me any further than the dead 160SC it came with.

 

I only got the flashing "missing system" icon the first time it booted after I added the batteries. I'm thinking I might have damaged something with my hardware swapping, but I can't be sure. I'd just like to see it get that far again for peace of mind. The only way I can do a PRAM reset is to remove the batteries as the keyboard doesn't do anything when sitting on the grey screen.

 

I used the IIfx floppy cable both when connecting the LC III floppy to the IIfx and the IIfx floppy to the LC III. The LC III's one was just too short.

Share this post


Link to post
Share on other sites

A friend called over earlier with a multimeter and the PSU checks out. +12v, -12v and +5v in all the right places. The batteries checked out too.

 

I just tried the hard disk from my Classic II but it still won't go past the grey screen (no rounded edges btw). So that's power ok and known-good HD not booting it. I've tried the hard disk cable from the Classic II as well, to ensure the problem isn't with the IIfx's cable. I've also tried moving the gfx card to another slot.

 

Board wash maybe?

Share this post


Link to post
Share on other sites
I just tried the hard disk from my Classic II but it still won't go past the grey screen (no rounded edges btw). So that's power ok and known-good HD not booting it. I've tried the hard disk cable from the Classic II as well, to ensure the problem isn't with the IIfx's cable. I've also tried moving the gfx card to another slot.

 

Board wash maybe?

 

Maybe, but it seems unlikely. Every IIfx I've seen has tantalum caps installed. I'm not sure what could leak onto the board that would need washing off, assuming the batteries have never leaked onto it.

 

Freezing at a gray screen can be an indication of a SCSI bus problem. Usually a very bad termination problem. So your problem may be as simple as the missing terminator. Both ends of the SCSI bus should be terminated, so even with a good terminated hard drive on the bus, you may still have problems because the IIfx end isn't terminated without the internal terminator. I think. I can't remember if the motherboard provides automatic termination if no devices are connected.

 

Hmmmm.

 

1) Have you tried it with no SCSI cable attached at all? This should get you to a flashing question mark.

 

2) If 1) fails, do you have a second known good SCSI drive and an internal SCSI cable with three or more connectors?

 

A) Do not connect any external SCSI cables.

B) Plug one of the middle connectors of the internal SCSI cable into the logic board.

C) Make sure that termination is enabled on both of your known good drives. Double check the jumpers.

D) Make sure that "Termination Power" (different from termination) is disabled on both drives.

E) Plug the known good SCSI drives into the connectors at the ends of the internal SCSI cable. One on each end.

F) Try it.

G) If that doesn't work try enabling "Termination Power" on one (only one) of the two drives.

 

3) If that doesn't work, buy or build the special terminator for the IIfx and try that....

Share this post


Link to post
Share on other sites

Thanks for the ideas.

 

I'm pretty sure I tried with no scsi cable attached and got the grey screen. I'll try it again soon and see what happens (I have it sitting with batteries out right now to reset the PRAM). I'll check the SCSI cable in my 7500 and see if that has 3 connectors. Then I could use that, the 7500's hard disk and maybe a scsi cd/dvd drive (otherwise I'll have to open up my Classic II again to get it's hard disk).

 

I've suspected scsi voodoo as I think I got a similar grey screen when I attached an external CD to my Classic II. It worked fine on the LC III but not on the Classic II until I attached a terminator to the CD enclosure. What's bugging me about the scsi voodoo situation is that the first time I powered it up I got to the flashing disk icon. So the current set-up of drives and cables etc and termination (or lack thereof) worked briefly yesterday. But not any more.

 

Update:

 

Booting with no scsi cable attached does indeed give just the grey screen.

 

7500's SCSI cable has 4 connectors so I'll work on taking that out now.)

 

7500's hard disk doesn't have any jumpers. Will it be OK to use two optical drives? I'm assuming the purpose is to have a SCSI device on either end. They don't have to be hard disks?

 

I went ahead and tried with the CDROM and hard disk from the 7500. The hard disk had no jumpers but the same drive/cable setup works without issue on the 7500, so I guess that means both are setup ok for termination. Still a grey screen.

 

Tried again with 7500 and LC III hard disks. Same outcome. Neither drive has any jumpers.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×