LC III: internal speaker works intermittently when pressing on the external audio jack. Audio plays through external jack when connected.

[theirongiant]

I have an LC III that boots and runs normally, but the internal speaker doesn't work. Well, at least I thought it didn't at first.

External audio works; I heard the startup chime, quacks, and wild eeps through headphones. By accident I was pushing the headphone jack while turning it back on, and the internal speaker played the boot chime. So I tried manipulating the jack with mixed results, and made a video recording of my experiments. (The audio on this video is captured by a Shure MV88+ microphone plugged into my iPhone and resting right next to the speaker. I unplugged the fan for these tests.)

See attached video, with sound on.

Perhaps you can advise me on next steps to repair this? I've already used 99% isopropyl alcohol and a toothbrush on the logic board, and sprayed some WD40 contact cleaner inside the headphone jack. No luck. Is it time to replace the jack? Is this a difficult part to find?

 

[GRudolf94]

None of that should look like that (as in, the solder being dull/crusty). You have a fair amount of corrosion damage - those caps need to be replaced, the board cleaned, and I suspect capacitor electrolyte has crept up into the sound jack and oxidized the contacts, so that the switch part of the jack no longer works properly, if it hasn't severed a pin.

 

[theirongiant]

Thanks for the diagnosis. What can I do about the audio jack?

Do you have a suggestion for cleaning or repairing this, besides a bath of 99% IPA ?

I had already talked the eBay seller down from their astronomical asking price because the computer was not booting off the hard drive, just a flashing floppy disk. I had spare parts to isolate the problem... but the Mac had visible rusting when I opened the case. I was pretty damn unhappy about that and have considered filing negative feedback and asking for a partial refund, because it was not advertised as having been stored in a moist / damp environment, or suffered a water spill. The hard drive was DOA, too, and I've already ordered a replacement. Thankfully, a BlueSCSI saved my butt; the computer boots up normally and (almost) everything seems to work by some small miracle.

Also... a friend of mine noticed the mixture of tantalum and electrolytic capacitors on the logic board. Had Apple transitioned to the new caps by this point in time?

 

[GRudolf94]

Ooof. I hope you ended up not paying much. Soaking it in IPA isn't gonna do anything here.

The whole thing will need to be serviced. If you don't have experience with surface-mount rework, this isn't the best place to learn. Anyway, ideally, while the board is out for capacitor replacement, the sound jack would be desoldered, which would allow for a better inspection of the condition and reveal issues better. It could also be a trace severed by corrosion, that makes contact when you flex the board. If that's not it, the side of the jack can be carefully opened, which would allow for deeper, more careful and detailed cleaning.

 

[joshc]

Also... a friend of mine noticed the mixture of tantalum and electrolytic capacitors on the logic board. Had Apple transitioned to the new caps by this point in time?

That was common. A certain portion would be tantalum from the factory, or ceramic sometimes I think for the smaller ones. I am not sure what the differentiating factor was, but there aren’t many models that had all tantalum from the factory (mostly Quadras).

As for your board, @GRudolf94 is right - the board needs to be reworked (e.g components removed, pads cleaned, new capacitors, etc).

 

[theirongiant]

Thanks.

I already wrote to the seller asking for a partial refund. They have over 10,000 sales and deal in vintage electronics. This should have been disclosed and I would have paid about half as much for a "parts or repair" Mac. In addition to having a hard drive that was DOA (I bought it as "blinking floppy disk" and took the risk that it might be dead, or might just need a reformat), but the floppy auto-inject mechanism was all seized up, too. Thankfully I was able to fix that with a quick squirt of WD40 under the sliding rails. The read/write head is fine, and so is the stepper motor, and the eject servo + gear. I got lucky with that component considering everything else that I found.

 

[joshc]

Even for a ‘working’ machine, I think all of that is to be expected and usually vintage electronics sales are offered as is without warranty. That’s at least the terms I sell all my stuff based on.

 

[theirongiant]

Even for a ‘working’ machine, I think all of that is to be expected and usually vintage electronics sales are offered as is without warranty. That’s at least the terms I sell all my stuff based on.

I totally understand that there's no warranty and no returns for stuff like this. I took a gamble and lost. I'm not against trying to repair this Mac, but I would have possibly skipped the listing or made a much lower offer if I knew about the water damage.

 

[GRudolf94]

Hm... Understandable if you don't wanna name and shame, but who on ebay did you buy that from? Or at least geographical location...

 

[cheesestraws]

By accident I was pushing the headphone jack while turning it back on, and the internal speaker played the boot chime.

To underline/elaborate the answer to your original problem, which @GRudolf94 did say but which has got a bit lost in subsequent conversation - the way the "cut off internal speaker when headphones are inserted" works is that there's actually a physical switch in the headphone jack socket which cuts off the internal speaker when a plug is inserted. These symptoms demonstrate that that switch is physically damaged: otherwise, poking the headphone jack wouldn't fix it. So you'll need a replacement jack to solve the immediate problem.

As both @joshc and @GRudolf94 have said above, you'll need to do some repairs/fixing on this board - but the only really urgent thing IMO is to get those surface mount electrolytic caps off. That, you will need to do regardless of what else is broken. After that, I might suggest a problem-driven approach to servicing the rest. Play with it, bounce up and down on it, etc, fix what doesn't work.

Do not just remove things at random that look crusty, muck around with them and put them back without actually knowing how to check that you've improved things. This is a great way to go quite mad.

FWIW, although the solder should not look like that, I've had boards that don't look much better last for many years before needing anything else doing to them. Don't do unnecesary interventions, and remember that LC IIIs are not priceless historical artefacts, they're mass-produced machines that survive in large quantities and are relatively robust. As time goes on that will change and they will become rarer - but nothing you do to this machine will change that or make time less inexorably grindingly destructive, so you just have to live with that truth, I'm afraid.

 

[danny.gonzalez.0861@gmai]

eBay is always hit an miss with these old electronics as it really depends on where these machines were stored and how.

cheesestraws said it best about your headphone jack. It has a switch internally that when in use, cuts power to the internal speaker. You are saying you have tried contact cleaner but if you just spayed it, that is not enough. You can use a generic headphone cable of low value and repeatedly insert and clean, respraying contact clear now and then. The hope is that whatever is stuck in there or any corrosion buildup will be "sanded down" to try and make better connection but the possibility does indeed exist that your port was damaged somehow in the past and no amount of cleaner will help.

Also, Grudolf94 pointed out some definite corrosion on some chip pins. After removing the electrolytic capacitors, drench the board in some white vinegar to try and neutralize any electrolyte that might be on the board, then IPA to clean that stuff off followed by a good thorough soap and water session. Let the board sit for a few days to completely dry and then replace caps. If your audio issue is not solved after all of that has been done then I fear your jack did indeed met its maker and needs to be replaced.

Adrian's Digital Basement has a few great videos on recapping boards, all though maybe not exactly yours, but the concept can be carried over. He also shows how to use the cleaning agents I described before and I think with a bit of knowledge and confidence you will have your LCIII working in no time.

Goodluck!

 

[theirongiant]

eBay is always hit an miss with these old electronics as it really depends on where these machines were stored and how.

cheesestraws said it best about your headphone jack. It has a switch internally that when in use, cuts power to the internal speaker. You are saying you have tried contact cleaner but if you just spayed it, that is not enough. You can use a generic headphone cable of low value and repeatedly insert and clean, respraying contact clear now and then. The hope is that whatever is stuck in there or any corrosion buildup will be "sanded down" to try and make better connection but the possibility does indeed exist that your port was damaged somehow in the past and no amount of cleaner will help.

Also, Grudolf94 pointed out some definite corrosion on some chip pins. After removing the electrolytic capacitors, drench the board in some white vinegar to try and neutralize any electrolyte that might be on the board, then IPA to clean that stuff off followed by a good thorough soap and water session. Let the board sit for a few days to completely dry and then replace caps. If your audio issue is not solved after all of that has been done then I fear your jack did indeed met its maker and needs to be replaced.

Adrian's Digital Basement has a few great videos on recapping boards, all though maybe not exactly yours, but the concept can be carried over. He also shows how to use the cleaning agents I described before and I think with a bit of knowledge and confidence you will have your LCIII working in no time.

Goodluck!

What I didn't include in that video was from a longer cut of 4 minutes, where I did indeed push a headphone plug in and out repeatedly after blitzing it with contact cleaner. Based on the smell and the properties of the cleaner, is it anything more special than just aerosolized isopropyl alcohol? (Dear lord, some people would try and huff that and make themselves go blind...)

I have considered using distilled white vinegar to remove the white mineral residue on the logic board from the previous water incursion. But I also read that vinegar might be corrosive to some components. How should I use it safely? Rinse with vinegar, then immediately follow up with distilled water, then IPA?

Warmed vinegar is way more effective than cold vinegar at dissolving minerals; I have to descale my electric tea kettle regularly because we have very hard water. Heating a cup of white vinegar to about 50ºC (120ºF) dissolves the caked-on minerals in seconds and the kettle is nice and shiny again.

Here are some photos of the underside of the board. What's my best approach here?

 

[theirongiant]

 

[GRudolf94]

I suspect the white residue is more leftover flux from when the board was soldered eons ago than it is minerals. There's no harm in leaving it as is. Vinegar would help neutralize capacitor electrolyte (which is alkaline), so you could bathe the board in it after removing the caps, followed by a dunk in IPA to rinse it all off. We're now way off the rails into "how to fix your average wonky Mac" land though.

 

[joshc]

The residues on the underside are nothing to be too concerned about, I’ve seen this on many boards that work completely fine

 

[theirongiant]

Where would I source a replacement audio jack component for the PCB? I tried search for some this morning and none appear to be a proper fit. I assume that Apple would have sourced a component in bulk at the time, but is it still manufactured? Or would I have to salvage the part(s) from another Mac destined for the trash heap?

Edit: I think I found an eBay seller who has the right one.

3-Pin 5-Pin 3.5mm Mono/Stereo Female Audio Jack Socket PCB Mount for Headphone | eBay

Find many great new & used options and get the best deals for 3-Pin 5-Pin 3.5mm Mono/Stereo Female Audio Jack Socket PCB Mount for Headphone at the best online prices at eBay! Free shipping for many products!

www.ebay.com

In the featured photo, I think it's part #3 from the left. PJ-323M. A vertical block with 5 pins arranged in a zig zag on the bottom with a black / plastic shell. A schematic is shown in photo 3, and a close-up in photo 6.

I'd have to order 10 @ $6.98, but I'm used to ordering moderate bulk quantities when I just need one piece.

 

[GRudolf94]

You're jumping the gun here. It's probably an obsolete part, I'm not sure if there's any modern alternatives with the same footprint, but it's probably also salvageable, and, at the risk of sounding annoying, I'm gonna once again hit on the key that you have corrosion issues to address first.

Fixing a sound jack is pointless if the rest of the machine is being corroded to nothing. Repairing a machine that is still alive is much better than spending days looking for microscopic breaks in traces. The problem is, of course, aggravated each time the machine is turned on in that condition.

 

[theirongiant]

...

 

[David Cook]

There is so much good content on this forum that sometimes really apropos material gets buried. If you follow my step-by-step method, you'll get your sound working...

LC III - No video, no sound, and weird schematic

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