HELP! Mac SE is smoking

[jsarchibald]

Hi all,

With the recent acquisitions I came across recently, I thought I'd spend the weekend cleaning them up and try to get some of the busted ones working again. I came across a Prodigy SE and an SE that worked quite well, but I have the 512K that trips the CB, an SE that did nothing when turned on, and an SE FDHD that has had the battery explode and ruin the motherboard (I may attempt a replacement of the affected components and cross my fingers that the board hasn't suffered much damage).

So, without checking compatibility, I grabbed the good motherboard from the SE and put it into the SE FDHD (the boards looked slightly different), and when turned on, I got a weird sound from inside (which I'm guessing is the HDD) and black and white horizontal lines. I looked for reasons this may happen, and it discussed RAM chips, but I had cleaned them all thoroughly, so I'm guessing there is more to it than the mobo, or the mobo I put into it isn't compatible.

Then I decided to swap the power supply from the SE FDHD into the SE with the original mobo back in it. When turned on, I got some white lines moving around sporadically in the middle of the screen, and then I smelled a strong chlorine smell with a slight electrical burn smell. I turned the machine off, and a thin wisp of blue smoke came out of the back of the machine, for about a second. The smell hung around for a while though.

Any idea what is happening here? I'm guessing the power supply was busted because of whatever this fault is, and the new power supply would go the same way if I left it on. I may have already done some damage. I figured I had nothing to lose, as both machines didn't work. Any help would be greatly appreciated.

 

[techknight]

one more lost macintosh soul. May it rest in peace. xx(

 

[Theretrogamingroom]

You killed it!

:'( or should I say xx(

 

[PowerPup]

Well, obviously the power supply is kaput. But the motherboard may still be salvageable.

Sounds like your SE motherboard has the common SimasiMac issue. Basically some of the capacitors went bad from age. You could get them replaced, hopefully the motherboard wasn't damaged.

 

[jsarchibald]

The power supply wasn't working, but the other one did. However, the original power supply is obviously being affected by some other part of the SE that is faulty. I don't think I've damaged the power supply, but you never know. I think there is something on the analog board that is causing the problem.

Yeah, it could well be the motherboard, I think it recommended replacing C6 and C7. I'll swap the power supply and mobo back over to the other machine and see where I end up.

 

[techknight]

What you need to seriously do is to sort out the good from bad before intermixing things.

For example, im sure pinouts are all over the web on the analog board connectors and power supply pinouts.

Then you can test for proper voltages on the power supply alone, with no motherboard. check for proper scan voltages as well.

Once you eliminated the good from the bad, power supply and analog board wise, then you can move onto the motherboard AND floppy drive.

ive only seen it happen ONCE, but its possible it could happen or has happened to you, is the floppy drive shorts. and holds a rail to ground. smoking out the power supply. or motherboard, or both.