Quadra 840AV Locking Up

[ianj]

I posted this to the Vintage Macs e-mail list too, but I'm trying to find help wherever I can. This has really got me worried because if I need a new motherboard or something, I have no idea where to get one.

I've been having a serious problem with my Quadra 840AV lately. It's been working fine for as long as I've had it, but just today when I turned it on, the entire system locked up when it got to the desktop. I hit Command-Control-Power Key to restart it, only it did the same thing. After a couple more tries, it started locking up earlier on in the boot process, at one point freezing up on the Happy Mac screen, which appeared faded out. Next time I tried to restart, it made it to the Desktop again before it locked up, and that's what it's been doing pretty consistently from then on. I assume I'll have to replace at least one system component to resolve this issue, but I have no idea which one. Could anyone point me in the right direction? In case this has anything to do with it, I replaced the system battery a couple weeks ago.

EDIT: Now when I try to start it up, it powers on, but I get no video and no startup chime.

 

[Unknown_K]

You can hold the SHIFT key down to bypass all extensions to see if you have an extension issue or some hardware issue.

Have you bothered to open the case up to see if anything looks funny internally? Have you changed anything to make the system unstable (software or hardware)? 840AV motherboards have been known to die from capacitor leakage, see if you have any major areas where dust seems wet around capacitors. Could be power supply related as well.

 

[ianj]

I just opened it up and looked around. Everything looked clean and normal as far as I could tell. I reseated all the RAM cards, reset the logic board according to the service manual's instructions, and put it back together with no improvement. What should my next move be from here?

 

[Temetka]

Remove everything that is installed.

Start with 1 RAM stick and the HD.

Boot it and see what happens.

Also check the PSU. Make sure it is functioning normally.

 

[wally]

I agree with Unknown K and Temetka, try to reduce the number of variables and/or things that have changed recently and see if it works better with less extensions, and even less optional cards if you have any inserted. Test the +5V and +12V at the disk connector with a voltmeter, unplug and replug all power connectors also. Even if you cannot see any wet around the motherboard capacitors, remember that the SMT types will start to leak directly underneath first before spreading. Should there be any surface traces running under the cap they will start getting random and growing connections to others in the vicinity, with symptoms that change the longer power is applied, and also, at least in the beginning, symptoms that can temporarily go away with an overnight power off! If you have the equipment, my favorite temporary trick is to ground the tip of a shopvac crevice tool with some foil and a ground wire, and use a squeeze/squirt bottle of denatured alcohol to spray/suction each SMT capacitor base, then let dry for 24 hours just to be sure before testing again. This is not a fix, if there is leakage the caps all should be changed.

 

[ianj]

Thanks for all the tips, everyone. I'm not too experienced with hardware troubleshooting, but I'll do what I can and ask about what I can't figure out. If this information is useful, I haven't made any changes to the system's hardware configuration since I got it (in May), so I can't think of any recent changes that would have made this happen. My best guess is that something failed. Would anyone venture to guess whether it's more likely that the motherboard or power supply went bad? The failure was gradual, but it all went down in about a 15 minute span. First there was locking up right after the OS loaded, then locking up in the Happy Mac screen, then nothing. I'll have to try the more involved suggestions tomorrow; I'll post on how it goes.

Thanks again everyone. This Mac means a great deal to me and I appreciate the responses.

 

[Forrest]

Is the fan on the power supply still working? Failure after 15 minutes sounds like a heat related problem and the fans are the first thing to check.

 

[ianj]

Is the fan on the power supply still working? Failure after 15 minutes sounds like a heat related problem and the fans are the first thing to check.

The fans all work fine.

I have very little experience working with electronics, and I don't have a voltmeter or anything with me right now, so I've gone ahead and ordered a replacement power supply and logic board. If that doesn't fix the issue, I don't know what will. Even if one of the parts turns out being unnecessary, I guess it couldn't hurt to have spares on hand considering I expect to use this machine for a long time and something else is likely to fail down the road. When they get here I'll see what happens.

 

[beachycove]

One thing that has not been mentioned: try a different scsi drive, or try the 840's drive in another machine. It may be that the drive's the problem.

I had this happen on a powermac once: the drive blew some small component on the bottom (as in, there was soot where it once had been), and the machine ceased to be - until I stuck a new drive in, that is.

The 840av does, however, have a known tendency to do what yours has done. Remedies vary: stick the logic board in the dishwasher, reseat all components, keep it running for 40 mins or so and then try re-booting. But if it has a bad scsi drive, it wouldn't be fixed by any of that, and replacing the drive would be an easy thing to try first of all.

 

[ianj]

The 840av does, however, have a known tendency to do what yours has done. Remedies vary: stick the logic board in the dishwasher, reseat all components, keep it running for 40 mins or so and then try re-booting. But if it has a bad scsi drive, it wouldn't be fixed by any of that, and replacing the drive would be an easy thing to try first of all.

I didn't know that. When I first got the 840AV and turned it on, I had this same issue, except hitting Command-Control-Power Key would make it restart properly. After that first time, I didn't have the problem again until I had a power outage, and it was solved just as quickly. I thought this had something to do with the system battery being dead (which I've since replaced), so I didn't think anything of it. Now I'm permanently stuck in that situation with the difference being that a force-restart doesn't work. The 840AV had been in storage in the previous owner's basement for some time (possibly years), so maybe the components were just weakened by being down there and not being used or something.

 

[Maccess]

The 840AV 40Mhz board is hard on capacitors, and tend to cause their earlier demise.

However, you seem to have gone through the usual suspects (PRAM battery, loose or defective RAM, etc.), except one: possible corruption of the disk. Seeing that you've gone through most of the steps I would have done myself, I would say the next thing is to check your disks, and system folder contents for corruption. You may have a corrupted extension and/or dekstop file.

 

[vassilizaitsev]

Rebuild the desktop,

I think it's the hard drive.

Try swapping the drive or formatting the drive, or fixing the drive, ie:- rebuild the desktop.

 

[ianj]

I just got a hold of a different motherboard, which got me to a couple successful startups before the same problem developed. The motherboard came with a full set of RAM, so I'm going to try swapping that in to see if my memory's bad. A new power supply is on the way, so I'll see how that goes.

Some of you are saying the hard drive is bad. I don't have any other SCSI disks to test this with, so could I check it out by simply unplugging the SCSI cable from the motherboard and trying to start it up? I can't do much in terms of software checks because in the few cases where I can the Quadra to start up completely, it locks up within a minute of loading the Finder.

 

[wally]

Here are some possible courses of action re your drive:

You could remove the drive and rig a cable to temporarily install it as an external drive (setting the SCSI ID temporarily to a non-zero available number) on another Mac and then backup any files that you want to save. After the backup you could run repair or disk recovery software (Disk First Aid, Mac Tools, Norton Utilities, or similar) on your known good Mac against the external drive to look for issues. If there is any doubt you have enough free space you could free up some, defragment the disk while still on the known good Mac and then try it again back on the 840av. If still problems, see reformat/reinstall below.

You can leave it in place initially and try to externally boot from some utility software like Norton Utilities or Mac Tools or even a MacOS installation CD just to get to a point where you can look at the hard disk directory and verify first of all that there is plenty of free space (as in many, many multiples of your main memory size). Then running a disk repair operation (Disk First Aid) or disk recovery program is a good idea, along with an anti-virus scan. This gives quite a workout to reading the disk but requires the CPU and memory to be good, and I have some reservations about attempting a defrag at this point on the 840av. If all appears well it is likely but not certain that the CPU, memory and power supply are good, but disk write operation integrity is not known and importantly there is a big question of whether the driver, boot blocks and MacOS image are all good or corrupt. Nothing quite like a reformat writing zeroes or ones with read verify after write followed by a clean install to reassure at this point, so a backup might be good first on another Mac, previously discussed.

 

[Temetka]

I have a 2GB SCSI drive you can have for the cost of shipping.

 

[ianj]

I'd like to add a few more details here to help the diagnosis. After working with the Quadra for a few days, I've been observing some really erratic behavior. Usually what I get when I try turning it on is what I originally described - power lights come on, fans come on, hard drive spins up, but no startup chime and no video. Occasionally I'll get the startup chime but no video, or the crash chime. Last night I turned it on, actually got it to load the OS, and used it for about a half hour with no incident. I turned it off and went out, and the next time I tried to use it later on, I got nothing once again. Today I haven't had any better luck, but just a few minutes ago I tried running it, got a startup chime and video, but when I got to the "Welcome to Mac OS" screen, the system threw up a bomb dialog claiming there was an "address error." I don't know if this information will help narrow down the problem, but I thought I'd share it just in case. With all this taken into consideration, could it still be just the hard drive that's wrong with it? I have a new one coming in the mail, so I'll try it out when it gets here.

 

[ianj]

Just put in the new hard drive today, with no improvement. This has got to be the most confusing issue I've ever encountered - I replaced the motherboard, power supply, and hard drive, in addition to trying all sorts of different RAM configurations. What else could be wrong with this thing?

 

[wally]

Not to exclude the possibility that one of the previously substituted units is also bad, there still remain some common elements:

the keyboard or mouse you are using could be continuously sending data interrupts (test them on any of your other ADB systems)

faulty motherboard to hard disk cable (substitute)

faulty hard disk power cable (may need to clean, crimp wire connections and connector contact barrels slightly if it plugs in too easily)

intermittent AC power line cord (substitute)

Also, take a careful look at the inside of the system cabinet, the air intake paths and the sheetmetal surfaces, looking for flaking plating or whiskering. You do not want tiny conductive things being blown around by the air cooling to land between IC connections and cause random shorts. A good cabinet disassembly and cleaning might be in order with compressed air and/or vacuum, with static electricity buildup kept under control, if you have any doubts here. One industry test is to gently apply ordinary transparent tape to metal surfaces (but not to ICs or circuit boards: ESD risk), peel, and carefully inspect the tape with magnification. Any metal particles is bad news.

 

[beachycove]

Still sounds very, very, very like a "scsi voodoo" problem to me, which in effect could be drive or cable related. The termination on the new drive is done right? Tried a different scsi cable? Here's another suggestion: boot without the cd connected, just to eliminate it as a factor. Who knows? Maybe the circuitry in it has died after all these years. I once junked a cd drive in a Quadra that prevented it from booting.

Half of the frustration in working on the 840av, of course, is that it take 30 mins to disassemble and reassemble the thing, especially if you are fiddling with the logic board. I know - I had one with gremlins too, in fact, I had one with several gremlins and almost gave up. I'm glad I didn't, though I do wish it weren't so yellowed.