Apple Se/30 making arcing noises

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CheshireNoir's picture
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Apple Se/30 making arcing noises

I have an SE/30 and it's developed a worrying fault.

When I turn it on from cold, it seems to start OK, but if I turn it on while "warm", it will sometimes make an arcing, crackling noise, which is quite disturbing.

 

The noise seems to be coming from around the power switch. I've stripped the system and I can't see any signs of obvious damage. I thought the problem may have been the power switch itself as it felt a bit "crunchy" so I stripped everything down and added some Deoxit, which made the switch a lot smoother, but I still seem to be getting "zort" noises on warm start. 

 

When it "zorts", the system seems unstable too (The boot screen is scrambled like the system has crashed. so while you can see what it was trying to draw, it's overlayed with checkerboard garbage. I can't get a photo as I immediately turn it off if it does this.) so further into the power supply?

 

Not sure what to check next. Open to suggestions. I'd guess it must be the power supply unit? I'll strip it further next weekend and see if I can see any more places the problem could be. I've visually inspected all the PSU capacitors and they all look fine.

 

This high voltage stuff is a bit more scary than the stuff I usually work with so I'm not afraid to say it's a bit "brown trousers" time for me.

 

Cheers and TIA.

 

Chesh

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RIFAs

Have the yellow box RIFA capacitors been replaced? If they are old, their cases will be crazed and cracked.

They are at line voltage and when they decay, sparks and usually smoke emanates from them.

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Not the RIFAs

I visually inspected all the caps and they looked fine.

The Australian APple II users group have now chimed in and they're all pointing at the PSU switch itself.

 

That's where I'll concentrate next I think.

 

Cheers!

 

Chesh

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It might just be the power

It might just be the power switch itself. Try leaving it on and using a power strip to turn on and off the computer. Do you still get the "arcing?"

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It was definitely the switch...

So I opened up the SE/30, and after some arguing, cursing and a little bit of work with a hot air gun, I was able to remove the existing switch.

I popped it open by sticking the tip of a pair of needle nosed pliers in the hinge point...

Ewww!

This is the contacts from in the switch. Very carbonised.

Thankfully Danny on the Apple II Oz mailing list had already found a matching switch (Marquardt Double Pole Single Throw (DPST), On-None-Off Rocker Switch Panel Mount (Model 1802.6123) - Found here) so I have ordered one. Should be here in a few days and I can hopefully put it all back together.

 

Chesh

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