Troubled SE/30

[Damian Ward]

I'm having trouble with one of my SE/30's. The SE/30 is booting from its internal hard disk, it loads all the extensions and control panels. Then displays the message "Disk initialisation failed because the disk is locked". I can click OK to clear the message but it then comes up again, leaving me no option to continue.

I believe it may be something on the analog board, as I have swapped the hard disk and logic board for ones I know work, but it still comes up with the same problem. I have looked over the analog board for leaking capacitors, but everything looks good. Has anyone else had this problem?

I have posted a picture on Flickr, showing the message. http://farm2.static.flickr.com/1108/3267548042_375cf31bb6_b.jpg

 

[tomlee59]

Here are some things to try:

1) Boot from a floppy -- does that work?

2) Check power supply voltages.

3) Although swapping boards should've cleared PRAM, perhaps it's not a bad thing to try (cmd-option-P-R at startup; wait for three consecutive bongs).

4) Check pram battery. If it's sort of dead, that can cause worse trouble than if it were totally dead, IIRC (different models behave differently, hence the uncertainty; my memory degrades with each passing day).

 

[Damian Ward]

I have just managed to get it booting now. I disconnected the floppy drive and it sprung into life. There is not a floppy in the drive so I think the heads must need cleaning or the drive has died. I will keep you posted if anything interesting happens.

 

[Apostrophe]

I've seen this in my Centris 610 too. Replacing the floppy drive fixed it right up.

The trick to know that it was the floppy drive is the message 'the disk is locked.' Hard disks are NEVER locked, at least not enough to prevent booting. That tells you instantly that the floppy drive thinks it has a disk inside it, but obviously can't recognize it.

-Apostrophe

 

[wally]

...There is not a floppy in the drive...

But perhaps the plastic microswitch sensor shaft on the front edge located switch to the immediate left of the rightmost one is stuck down from crud.

 

[tomlee59]

As usual, Wally has a great suggestion. It is not uncommon for gunk to foul up microswitches, fooling drives into thinking that there's a disk, misinterpreting the density, or thinking that the disk is write-protected.

 

[Damian Ward]

It defiantly looks like the floppy drive was the problem. Now that I have removed it the Macintosh starts up fine.

I have given the floppy drive a bit of a clean up, as it was full of fluff and dust. I also made sure that the mentioned microswitch is free to operate.

I also think that it could do with some grease to lubricate the movements. We have some silicone grease at work do you think this would be suitable?

Thanks for all your help.

 

[Dog Cow]

If the switch for detecting the locked state is stuck down, then it will think every disk is unlocked, since usually the tab on the disk will press it down.

 

[Charlieman]

Hard disks are NEVER locked, at least not enough to prevent booting.

Many Mac security software products DO lock the hard disk. My experiments suggest that the products modify the System file or boot blocks so that the hard disk is flagged as locked every time that the Mac boots. A security INIT is then loaded which requests a password to unlock or decrypt the hard disk -- this is always at the start of the extension loading process, so that INITs that require a writable disk (eg AppleTalk Chooser extension) can function.

Note that the disk may not protected after it has been unlocked if the OS crashes (or you flip the power switch). Depending on software sophistication, the disk may be mountable in another Mac.

Lock/Unlock utilities for hard disks were common in the 1990s, because they allowed content for CD-ROMs to be developed and tested on hard disks.

 

[Charlieman]

If the switch for detecting the locked state is stuck down, then it will think every disk is unlocked, since usually the tab on the disk will press it down.

Well observed. Which means that cruft and dust (wonderfully conductive stuff) were the likely causes.

I'm sure that I have mentioned this before, but here goes... A web server on a low end PowerMac spontaneously rebooted from time to time. The cause was a bundle of fluff inside the Mac and surrounding the external reset switch. Depending on the weather (literally), the fluff acted as a switch.

 

[wally]

...some grease to lubricate the movements. We have some silicone grease at work do you think this would be suitable?...

Hmmm, usually silicone is not nearly as slippery as mineral oil/lithium grease like that at http://www.cyclesuk.com/337-518016

The silicone stuff is usually better reserved for contact corrosion protection and to keep rubber from sticking. It might be good for plastics, for example if the microswitch plastic shafts bind, or for plastic gears (provided that the particular formulation is compatible with the plastics). But for metal to metal mechanisms I'd recommend regular lithium grease (need not be white, but no moly, no extreme pressure additives) used sparingly (which means apply some with a clean screwdriver tip, work the mechanism some, then wipe off the excess grease at other than the friction areas). Since grease acts as a dust magnet, best to have it exposed only where it is really needed.

It's really important to clean out the old gunk first before applying new grease, and sometimes this requires mechanically chipping crud away if solvents do not cut it!

 

[Damian Ward]

Thanks everyone for their help, the SE/30 is up and running again and harmony has been restored. I did have a bit of trouble finding the lithium grease in the shops, but a ebay seller came through in the end.

Thanks again for you help. :beige: