Identifying and locating source of possible blown capacitor smell

October 7, 2022 6:36 AM

Okay hive mind, help me maintain my sanity. For a couple of weeks there's been an odd smell in my home office. Best I can describe it is like the sweet smell of fermenting apples combined with an acrid chemical smell. As the smell has been getting worse, it's started irritating my throat and giving me a headache. From extensive googling, I suspect it's a blown capacitor. In my office, that means the smell could be coming from one of two MacBook Pros, or a couple of LED bulbs, or an LG monitor. But....

Here's where it gets maddening. I have put my nose up to every component in my office and simply can't hone in on the source. I've turned them on and off, unplugged them. I've even tried electrical outlets. I thought I was losing my mind, but my wife can smell it too. In the morning, if everything has been turned off and unplugged, the smell is gone. I've tried plugging things back in one by one, but I do that and there's no smell - until hours later, when it's back, and I still can't find the source.

So:

Has anyone had an experience like this? Does the smell sound like a bad capacitor, and are they typically hard to pin down? Am I missing anything? FWIW, I've gone so far as to get a plumber out to my house to make sure it's not sewer gas or anything plumbing-related.

posted by bassomatic to Computers & Internet (12 answers total)

It does sound like a bad capacitor. I know you've already tried the outlets, but you didn't mention checking the power bricks, wall chargers or power strips in your office, which in my experience are the most likely devices in the chain to fail this way these days.
posted by eschatfische at 6:48 AM on October 7, 2022

could also be melting insulation on a cord?
posted by nouvelle-personne at 6:52 AM on October 7, 2022 [1 favorite]

Could you, over the course of a couple of days, take each one into another room, plug it in there, and see if the smell arises over the next several hours...?
posted by ManyLeggedCreature at 7:04 AM on October 7, 2022 [7 favorites]

Weird.

Most capacitors emitting smell do so pretty briefly, and generally have it accompanied by sound as well as smoke (a kind of very concentrated and visible smell).

This appears to be a capacitor overheating but not failing disastrously (yet), which does indeed happen occasionally. Could even be that it's a nearby component that's the actual culprit causing the capacitor to fail relatively slowly. Hard to pin down indeed, even when you have found the actual device.

I'd consider leaving each of the suspects powered on overnight, one by one, although I can understand if you feel reluctant to do so; then the next best method is what ManyLeggedCreature suggests.
posted by Stoneshop at 7:28 AM on October 7, 2022 [1 favorite]

If you have a line power monitor, like a Kill-A-Watt, you could sample the devices. That kind of energy dissipation might leave a device a watt or two high of their idle spec power.
posted by nickggully at 7:57 AM on October 7, 2022

I'm gonna say something stupid, just in case: Does this room have an overhead light or any other light you turn on via switch when you first walk in? Because in our household, we were going *nuts* trying to find a smell like you describe, and of course we eventually realized it was coming from the ceiling light. We were just switching it on when we came into the room without even thinking about it.
posted by BlahLaLa at 8:12 AM on October 7, 2022 [6 favorites]

The only time I experienced this, it was a swarm of ants in a pre-amp. The smell was very maple syrupy to me. The ants like the warmth of electronics and can gather in there, then as the electronics warm up, the smell starts. This was in New England around the turn of the season, and I see you're in Vermont.

Have you tried opening up any of your larger components? Or could there be circuit boards in an air handler in the wall?
posted by cocoagirl at 9:01 AM on October 7, 2022 [3 favorites]

If you have a line power monitor, like a Kill-A-Watt, you could sample the devices. That kind of energy dissipation might leave a device a watt or two high of their idle spec power.

For such a test you will also need a time machine, to go back to Before Smell times and measure each device's nominal power usage. For a monitor this might be not too different from what's printed on the label or in the manual, but that number still is not precise enough to find those extra two watts.

A PC or laptop's power usage is VERY variable, and depends on so many factors that this method just won't work anyway.
posted by Stoneshop at 9:05 AM on October 7, 2022 [1 favorite]

I also came to suggest a light fixture. I’ve blown tubes and large capacitors on various electronics and it has always followed the pattern of magic smoke, bad smell, thing stops working. The big old school electrolytic caps you might find in an old stereo amp might leak and stink before they go entirely, but the teensy surface-mount ones on a modern motherboard tend to just kinda fail without a fuss IME. I’d start with light fixtures then heat test power bricks and power strips.
posted by aspersioncast at 9:41 AM on October 7, 2022 [1 favorite]

it has always followed the pattern of magic smoke, bad smell, thing stops working.

Or not. I've more than once had capacitors go boom with the device they were in just continuing as if nothing happened. Usually those were mains interference filter caps, but one-of-many on a computer mainboard popping its clogs doesn't always take the entire system down either.
posted by Stoneshop at 11:03 AM on October 7, 2022

Response by poster: Update: I've ruled out all lights, outlets, power strips, etc. Seems to be down to one of the MacBook Pros or the monitor. I've opened up both MacBooks and don't see anything obvious, but did call my authorized Apple repair shop, and to them it sounds like a bad battery. I'm scheduling an appointment as soon as I can be without the laptops.

Will post the results of an official analysis!
posted by bassomatic at 10:32 AM on October 10, 2022

Response by poster: Last update. This got weirder than expected. First, we trapped a shrew in the basement and learned that shrews emit an incredibly pungent, skunk-like odor for such small creatures. That appears to account for part of the mystery smell. But not all of it, because I'm still getting hit with odd odors, at home and away, that range from bitter chemical to organic decay (fresh ground coffee, for example, smells like something rotting in the fridge). Since no one else notices these odors, I suspect COVID-related anosmia, which ticks all the boxes from symptoms to time of onset after testing positive. I've scheduled a doctor appointment to discuss.

Thank you all for playing What's That Odor, where the correct answer turned out to be None of the Above.
posted by bassomatic at 5:09 AM on November 7, 2022 [2 favorites]