My Performa 400 (LCII) just died :-( !

[Snial]

I keep waxing lyrically about my 31 year old Performa 400 that just seems to keep on going. The Mac resides at my Dad's house, but when I tried to power it up earlier today I got nothing. I did plug in one of the Macintosh LC microphones that I got with the Mac, but I don't think it's likely to short (is it?) and I would have thought that that wouldn't blow the whole board.

So, I guess it's most likely to be the PSU (or. a fuse?). It's never been recapped. I took the lid off and powered it on, but the fan didn't go. Rats I didn't even check if it was a mains fuse that failed. Anyway, here's what the inside of the Performa 400 looked like:



It has an ethernet PDS card (10-base T). The PSU seems OK.

No caps appear to be bulging, doesn't seem to smell. I've just checked the internal PSU fuse and that seems to be OK. I guess the next test is to power it and check the voltage outputs? Do I need to apply a load? If so, where?

Thanks in advance, Julz.

 

[Unknown_K]

Have you ever had the motherboard recapped? There are capacitors directly next to the power supply cable.

 

[3lectr1cPPC]

Yeah those caps look original. Both need to be addressed, there's no such thing as an LC II that doesn't need to be recapped in 2023. These have hard power though so if the PSU fan doesn't even spin then you probably have an issue there too, it likely died. Very likely also due to bad caps, the LC PSUs are notorious for them, even if nothing "looks" off.

In any event I see corrosion on the pads for the couple of SMD caps visible near the PSU, they need to be changed.

 

[chiptripper]

Echoing what's been said above. No power = bad PSU. You can probably get away with leaving the big snap-in capacitor, but all others in the PSU will need replacing.

And the logic board caps should be done asap too. There are a bunch under your ethernet card and given enough time they'll nuke your sound chip.

 

[Snial]

Hi folks, thanks for the answers, I'm aware that the standard approach is to recap such an old Mac, but it genuinely was helpful to have the two caps near the power connector pointed out. I won't be visiting my Dad for a couple of weeks, so in the meantime I wanted to check the PSU itself, is it possible to just power it on (after closing the casing) and check the power connector with a voltmeter? Do I have to apply a load between any of the pins? Is there a guide to testing it?

For example, for all I know, the fuse failed in the mains power lead plug itself (UK mains plugs all have fuses) and the rest of the system is still fine (though I'll start on a project to recap the PSU).

-cheers from Julz

 

[cheesestraws]

I've tested LC PSUs with a multimeter under no load, though it was quite a long time ago.

As far as I remember, it worked fine - the voltages were a bit off relative to what it would be in circuit but I could at least check that it was producing about the right voltages.

 

[treellama]

You should replace the caps, no question, but also: check continuity across the power switch. Those fail in LC II PSUs. I was able to get mine to power on (after re-capping) by bypassing the switch!

 

[DrGonzo]

Another vote for recap of both PS and board. I've had more LCs than I can count that came right back to life and ran good as new after. The longer you wait, the less likely this will be the case.

If youre not comfortable doing it and depending on where you live, I'd guess someone in your area might lend a hand for the cost of parts and a sixer.

~Dr. G

 

[Snial]

Thanks for the advice, I think after this scare, I'll start ordering some caps. Thanks @DrGonzo, I'm reasonably OK at soldering, even some pretty tiny surface mount stuff (402 resistors?).

Meanwhile doofus confession time. In my haste when I visited my Dad a couple of weeks back, I'd actually plugged in the wrong mains plug. Plugging in the one that actually had the kettle lead socket plugged into the LCII brought it back to life!



Colours are super vibrant - the Performa 400 casing looks much better in real life, not mottled nor yellowed at all!

Have a good weekend!

 

[joshc]

Ah yes, it does always help if it’s plugged in doesn’t it. We’ve all been there - I actually made this mistake the other day.

 

[cheesestraws]

Ah, yes. I do this quite regularly.