Mac IIsi a fire hazard??

something in the power supply?

sniff around

Something clearly blew in the power supply. Take it out, open it up, and take a picture of the damage! Maybe it can be fixed easily, maybe not, who knows.

Doubtful that it could have ever started a fire.

Don't try that PSU as-is again. I also don't think it would set the Mac ablaze, but safety always comes first, especially if you've got sparks flying everywhere. Definitely repair or replace, whichever you're more comfortable with. Also, make sure it's disconnected from the wall at all times until a remedy is found!

I agree, pics are a must.

onoz, teh magic smoke haz axcaped!

I'm not totally sure if i'll rip apart the PSU for repairs, considering that my school has a whole 'nother IIsi which is slightly less hazardous. However, I am curious as to what caused this. I booted it several times earlier w/o such a severe event; perhaps it was a one-time thing, and by that I mean it's never going to boot again.

Sometimes it can be the tiniest visible break in a component that releases a massive flash of light, sparks, a stench that fills the room and enough noise to skip a few heartbeats.

This was one of those - http://en.wikipedia.org/wiki/File:No_blue_smoke.jpg

I had similar happen inside a Quadra 840AV PSU - it was a voltage regulator IC, from memory. Also rather small damage for the noise, light & sound it made

Dana

Almost any kind of component can go kerpow like that. (Last one that happened to me was a flat-pack IC on a fairly recent hard disk's circuit board... the odor was positively unreal.) It could of been a voltage regulator IC, transistor, capacitor... I've even seen vaporized resistors and diodes.

If you crack open the power supply it'll probably be obvious what detonated, and if you replace it it'll probably be fine. (Well, possibly not. Sometimes a part will release its magic smoke because something upstream from it got shorted or failed in a way that it's letting far too much current past, so a replacement part will also go *bang*. Thus requiring some more in-depth troubleshooting.)

I'd put a nickel on it being a capacitor, or a regulator that failed because of a *shorted* capacitor. Any Mac II-series box is 20 years old now. (give or take about three years.) Computer collectors who are serious about using their machines rather than just displaying them are going to have to start accepting the fact that some parts don't last forever, and the limiting factors are more strongly correlated with age rather than how much use the machine gets. I wouldn't bet on another IIsi being any less likely to go *BANG*.

For the short term I'll exchange either the network card or PSU between my two IIsi's, once I have both of them. However, when I saw this flash, it was almost wholly outside of the case, as if the flare of whatever vaporized was channeled out by the exaust fan - the IIsi doesn't have any vent on it's rear that opens to the PSU.

What precautions should I take when inspecting the PSU? I don't need a capcitor to discharge into my arm.

I bet it was a cap too, regulators usually burn not explode (though you never know), as far as safety have it unplugged (done) for a while and it should even back out, if your paranoid you can use a (insulated handle) screwdriver to short capacitor leads together

Storage location is an important consideration. If your old Mac has been stuffed in a loft, garage or anywhere damp, treat it with respect. Bring it indoors, to a nice warm and arid environment, to allow it to dry out. For about a week.

All of my psu bangs with Macs have occurred when I failed to observe the above rules.

I have discovered the cause of the magic smoke release. It explains quite a bit (including why the flash occurred outside the case) and it may surprise you.

No, it wasn't the PSU, it's perfectly fine:



Uploaded with ImageShack.us

It was the NuBus riser card:



Apparently, when this cap (or whatever it is) blew, it sent a massive amount of voltage up the network card ribbon cable (on left). Then this excess voltage found the path of least resistance, which I believe is the RJ-45 outlet. This would explain why I saw a flash outside of the case, not exactly at the psu.



I didn't see this until I was about to pack it up - I noticed a very small scorch mark right on the pcb itself, with an orange shard of capacitor nearby. The motherboard itself has no orange-colored capacitors, and the PSU has none that are that small. A little more searching and I discovered the rest of the carcass on the NuBus card.

Ah, another one of those FRIGGEN tantalum capacitors.

tantalums are notorious for that as they age. they will short and explode. ive seen plenty of leader test equipment do this very same thing.

once one of the tantalums go, the rest will follow eventually. every single capacitor needs replaced, including the tantalum.

if the cap was just on a power rail, its LEAST LIKELY it has done any damage outside of the capacitor itself.

Best of all, it appears to be very easy to fix, and everything will probably be just fine.

Tantalums will go boom eventually, they cannot stand much over voltage at all by design (which you get when regulators in the PS age). I have a Daystar 040 PDS accelerator card I recieved with a blown tantalum capacitor, works fine as is but I replaced it anyway.

http://picasaweb.google.com/teozenios/NubusCards#5067908435668848786

Bottom right, hard not to miss.

yup, but you missed the one on the bottom left though...

I managed to test out the IIsi's hard drive by puting it into my LC and then booting via boot floppy.

I have never heard a hard drive frantically click so loud in my life. it currently sits on my desk, dissembled for the fun of it.

So far this IIsi has been nothing but a disappointment. Riser card exploded, hard drive is faulty, memory useless for the 575, and the power supply probably doesn't regulate the voltage very well.

And I already have an auto-inject SuperDrive! Well, at least the battery isn't dead.

you could always strip it down and sell the ROM simm to an SE/30 enthusiast.

None of my 9 iisi's have ROM SIMMs, they all have onboard ROM. How common is it for them to have the SIMM?

Very rare early production units I think.

I thought so... I remember seeing a few IIsi units in my time and i only ran into ONE that had a ROM SIMM. rest did not.

It appears that my IIsi is really dead. I got my video converter in today - the IIsi gives no display when booting, so no sad mac after the chimes of death.

Hmm

You're consistently getting the chimes of death now?

Death chimes don't always provide video. From my experience, <50% of real death chimes show anything on the screen. The Mac must still be fairly healthy if you do get the chimes, it requires a lot of good hardware to get that far. A severely damaged Mac will not chime at all. Also, your video adapter might not be configured right, or won't work with your particular monitor. Old Macs like the IIsi often lack standard sync signals.

Do you have the board installed with the blown capacitor? Make sure to try booting with that board removed. Also try cleaning the logic board. Most of my IIsi's came with major capacitor leakage.

I do not have that card installed - of course I removed it. The motherboard appears to be pretty clean. I managed to get it to boot without death chimes, by removing all of the memory modules, and even read a boot floppy, but it halts after a point. Still no display - my adapter has multiple modes - would it be helpful if I posted a pic of it here?

Sure, that would help, maybe one of us could find a clue and provide more suggestions. Also, if possible, try it with several different monitors. I have a graphite Studio Display and an LCD that will NOT work with IIci or IIsi, yet I have a couple of other Trinitrons that work perfectly or partially (green/washed out/etc). Some screens are more picky than others.

The way it sometimes works and sometimes doesn't screams "bad caps" to me. I'd at least run it in the dishwasher to remove any invisible leakage and conductive particles. Or replace the caps. A sloppy power supply could also cause the crashing and capacitor explosion you've witnessed.

Here's the ebay page for the converter I bought, the one in the pics is identical to what I have:

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=260625981691&ssPageName=STRK:MEWNX:IT

Currently I'm using an IBM monitor, my only spare, although i've got a Dell CRT in the garage I could drag out. I'll try it on that and my LCD's as well. Heck, I could even try it on my TV :lol: big screen System 7!

I used to have exactly that video converter... what setting are you using? I would try the "13 inch 640x480" setting, not any of the multimode ones. I don't think the IIsi supports any higher than 640x480 (see Here. The IIsi can use *at most* 320k of onboard RAM for video. ) and it *may* predate the Macs that supported "normal" VGA monitors.

Fair warnings, LCD monitors may not care for the "13 inch" mode, but most CRTs should at least pretend to work.

@Gorgonops i'll try that out, I was using the multimode settings.

BTW, someone had upgraded the memory in my IIsi - it has 4 simm's, 2MB each. However I doubt they work anymore...

Tried two Dell monitors and a LG LCD monitor, no luck. Is it possible that my converter is faulty?

From what I see here, try setting the adapter with switches 1 and 2 on, the rest off.