Vintage Cherry smell

[Findecanor]

Last night, I took my old Cherry G80-0915 / Commodore PC-keyboard, (once showcased in
this thread) out of storage to look at it.

It had been in a plastic bag to protect it against its attached cable, inside a cardboard box.

It smells like old electronics, but ... incredibly strongly. It reeked, of a chemical smell. Almost as if something has been burned (but nothing has). I put it out on the balcony to weather it out overnight.

The next morning, I opened it up expecting to see capacitor leaks to clean up ... but nothing. It looks completely normal.
I cleaned both sides of the PCB and insides and outsides of the plastic case with isopropyl alcohol.
Still smells. I think the smell comes from PCB ... or perhaps from the switches.

What the hell happened? And what can be done about it?

Do I have to throw away the innards, and replace them with a placeholder or replica PCB? (the latter which would have to be designed and printed, in that case)

[doomsday_device]

mine smells exactly like this too.

[Lanrefni]

Plastic and fiberglass can continue to off gas volatiles for decades, keeping it in the plastic bag most likely concentrated it on the surface, try leaving it in a well ventilated place out of the sun for a few days to see if that lowers the smell.

[kbdfr]

I had the exact same problem with the exact same keyboard, although I think it smelled more of a wet basement (I simply don't know how old electronics smell). I ended up putting it (opened ) in a closed plastic box on a plastic gitter over one pound of ground coffee for several days.

In the end it still somewhat smelled of wet basement, but the coffee smell was much stronger and quckly faded, the basement was still there but quite "decent" now.

But it was years ago, perhaps I should take a new…smell.

[Findecanor]

I've cleaned the PCB. Still smells strongly. I have cleaned the case and keycaps separately.
I put the PCB on the balcony to air. If it has not improved on Sunday, I'll seriously consider throwing the PCB with switches away...

I could probably build a jig for the keycaps just for show, using a bag of MY modules glued to a piece of keyboard or similar. I am not fond enough of the layout to design a replica PCB.

I'm going to look through the rest of my collection for other smelly keyboards. I remember some other vintage G80 keyboards also having this smell, but at much lower strength.
I'm considering putting bags or mats of active carbon into cavities of my other keyboards, as a method to absorb outgassing from PCBs inside them.

[Findecanor]

Hmm. The switch side still smells.... I'll let it air out for a while longer before I'll even think about putting it together again.

I made a replacement ECD shield out of some cardboard and aluminium tape. I dunno if it is completely conductive, considering that I needed three strips of tape, but does it have to be?

[vvp]

Vacuum chamber should help. You can try a higher temperature as well. It should be safe up to around 65 °C.

[Findecanor]

Hmm.. At one time, I used to be doing silicone and resin casting, and pressure chambers are used to get the bubbles out of those materials before casting. But I never saw a pressure chamber large enough to fit a full-sized keyboard PCB...

I smelled my other Cherry G80 keyboards. After several years in the same box they too smell. The oldest smells the most and the newest smells the least. But my Commodore PC keyboard was my very oldest, and the PCB still outstinks the others by far. So much that I start coughing if I spend too much time with it before opening the window to ventilate.

[vvp]

I kind of assumed you want to de-smell only the switches.

Big vacuum chambers can be bought. They are pricey though.

Maybe you can make one from a thick walled sewerage pipe. Run your design through some FEM package to check it will not implode. Test safely before actually using.

It is a good idea to lower the pressure slowly. So that the PCB does not delaminate if it is really crappy. Electrolytic capacitors may not survive this.

[Findecanor]

I'm sorry, I thought the whole PCB was what you meant. I will throw away the PCB.
I have desoldered the Grey space bar switch, and unscrewed the screw-in stabilisers. I'm not convinced that vintage Cherry MX Black switches are worth saving.

From another thread I've posted on a Swedish electronics-engineering forum, I've been told that the PCB is likely made with phenolic resin, and the smell should be from formaldehyde — which can cause cancer. That riled me up a bit, because I was treated for B-cell lymphoma last year.
I read some medical articles on the subject, and thankfully there are no known links between formaldehyde and any of the types of cancer that I have suffered from.
But I suspect that formaldehyde from my keyboard collection could have been the cause of some nasal/sinus irritation I've also had for a few years ...

I had also contacted Cherry customer service, to ask what the PCB was made of and what the smell was. That was (of course) a complete dud: customer service drone reply, possibly written by ChatGPT for all I know.

[vvp]

Maybe you can find some indicators to detect formaldehyde to check the hypothesis. E.g. chromotropic acid method, spectrophotometric methods. Hospitals use some formaldehyde detectors to check their sterilization equipment (this is not likely to detect very low concentrations though). Anyway, the point is that formaldehyde is commonly used and it should not be that hard to get your hands on some indicator to test for it.

I doubt customer service will want to cooperate. If their hardware releases some nasty stuff then they do not have much incentive to disclose it. It would only open them to lawsuits. At the very best they will ask you to return the hardware to them for a tiny refund.

If I would be at your place then I would try the vacuum chamber. Just for the fun of it. Or I would just get rid of all the smelly stuff. But that is me. Despite being on deskthority, I'm not into vintage stuff. I care only about ergonomic stuff.

There is an easier and less reliable way to try also: just leave them in a hot, dry and well ventilated place for a long time (week, month). Also e.g. a food dryer may help - about 60 °C for a few days. If the dryer is from steel then it is likely it will not be permanently contaminated by it. Maybe you can put them into a bigger diameter pipe and use a hot air gun to blow hot air through the pipe for a few days. In such a case, you do not need to worry about contamination of a food producing gear.

[Findecanor]

I threw away the PCB. I think my other G80 keyboards have PCBs of a different material that is not made of (as much) phenolic resin.

I got a tip on another forum that active carbon could absorb formaldehyde, so I packed some active carbon filter matting in the empty bottom of my G80-3000 which was the one that had smelled the most of the remaining ones .... although that might have actually been because it had been stored in the same box as the Commodore.

[keycap]

I have a Unitek K-156 and it also has this issue. I see it sometimes on other boards as well, but it's very strong on the Unitek. It seems to mostly be with PCB mount variants, but that may also just be a frequency thing. Very odd phenomenon, and I'm not much of a chemist to guess what's going on here but I can DEFINITELY vouch for it being a real thing and you not being insane.

[Findecanor]

The most likely cause is that it was a PCB made of phenolic resin from which there has seeped formaldehyde over time.

The smell still lingers in paper bags stored with the PCB only for a week or so.

A mesh bag with the screw-in stabs and the spacebar-grey switch have been on the balcony to air out for a month, but they still smell.