Horror Show: Acid Bath

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So I finally got myself together enough to tackle stripping down the Acorn A4 laptop. I’d been somewhat nervous about it because of all the admonishments on the forum that it’s a nightmare to get apart, and that it’s fragile. Now the latter part is true – it’s 30 years old this year – and the plastic isn’t…great.

By the way, this isn’t going to be detailed instructions – because they’re here: https://www.chiark.greenend.org.uk/~theom/riscos/a4/dismantle.html. Y’all don’t need me to reiterate them (although perhaps twenty seven eight-by-ten colour glossy pictures with circles and arrows might be necessary ;) ).

That said, step one – remove the econet expansion cover didn’t go very well. Folks on the forum said it’s super stiff y’just have to do it – so I applied more force and the econet expansion cover kinda disintegrated as it came out. Not completely, I can glue it and it’ll look okay externally. I am unsure if it was that way before I started – I mean, I clearly broke one of the tabs – but to be fair it looked like it was corroded in. There’s also some breakage around the vent, but again, I think careful gluing from the back will salvage it.


…because at some point this has had a significant battery acid leak. There was battery acid trapped under the edge of the LCD, there were crystals of NiCd corrosion on the vents…

PXL_20230216_203124152.MP PXL_20230217_004606056

Interestingly, though, despite some very ropey bits of the board – at least two of which are going to require me to reference the circuit diagram and work out what resistors (assuming they were resistors) go in the place where there’s now a just corroded pads with some solder on there and spaces… the acid damage isn’t as bad as I feared. It’s not as good as I could have hoped (had I not seen the crystals through the vent at the left edge of the case). But it does look – salvagable? I hope. But it’s also clearly been apart before. These resistors are apparently not OEM (which explains them, because I thought they were odd):


But also the IDE connector is missing. I’m going to replace the IDE drive with an SD through an IDE adapter. At least, I hope I am. That’s the plan. But it will, iirc, still need the cable – which is kinda annoying. I’m hoping I have the right size of connector sitting around… because otherwise it’ll be something else I need to order.

One thing I don’t need to order – and where I was (fortunately) proven right, is the screen. I ordered that on spec when I paid for the laptop, because I suspected the dead bit of the screen (right where scroll bars will land up) was, in fact, from a screen problem. And I was right, it’s a nasty, unfixable problem:


Yeah, that crack in the corner explains the strip of dead pixels. It must have happened on reassembly – yet more evidence this thing has been apart. What’s so weird is that it must have been apart – and then whoever did it put this board in which isn’t in quite as bad-er shape, despite the case being obviously contaminated with NiCd juice. So having got it all apart I spent today basically ignoring the advice not to wash it – and went ahead and washed it. At the moment, there’s a bunch of bits from one of the Acorn NOS suppliers – and it’s sorely tempting to just get that and put it all in a brand new case. But I also like the fact this is clearly a pretty early one (although, tbh, it may just be they bought all the cases right at the beginning).

I also got an ESD safe brush and threw some alcohol at the board…





So I need to work out what the missing components are, and I need to also work out what the variable resistor that controls the contrast is meant to be: Then I’ll have to replace those SMD resistors, which will no doubt be super fun on a board that’s corroded like this… and *then* I can use it to write on.


More pics as usual, here: https://www.flickr.com/photos/49965961@N00/albums/72177720306075058


Kate's allegedly a human (although increasingly right-wing bigots would say otherwise). She's definitely not a vampire, despite what some other people claim. She's also mostly built out of spite and overcoming oppositional-sexism, racism, and other random bullshit. So she's either a human or a lizard in disguise sent to destroy all of humanity. Either way, she's here to reassure that it's all fine.