Mecahanical failure of PCB's - Laptop edition

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Mecahanical failure of PCB's - Laptop edition

Post by rubber_jonnie »

I've had mechanical failures of PCB elements before that have caused things like track breaks leading to faults that need repairing, but I was working on a laptop I've had for some time, that would power on only on battery, but not on the AC adapter, and a repair has eluded me for some time, years in fact.

But today I said 'No, today is the day I at least diagnose the problem', so I set about disassembling it, and the usual many screws later and it was all apart.

I started probing around and decided that I should start by buzzing out from the power socket, to see how far the 19.5v was getting into the board.

As it happens, it turned out to not be very far at all. Literally next to the socket is an inductor, and checking continuity from one side to the other, and nothing. So I started to look under the magnifying glass, and it looked like one side of the inductor had a cracked joint, so I got the microscope out to see if it really did. Boy did it:

PXL_20231024_124723451.jpg (561.2 KiB) Viewed 195 times

So, a spot of flux, a cleanup and some fresh solder, and continuity was restored. It just goes to show how useful continuity tests are, and visual inspections.

All now running off the AC adapter:

PXL_20231024_132859685.jpg (264.84 KiB) Viewed 195 times

Slightly annoying in that I could have probably fixed it years ago, but thought it was probably something much more complicated than a simple solder joint.

But there you go, a mechanical failure almost certainly as a result of a drop in that corner causing the board to flex and cracking that solder joint.
Collector of many retro things!
800XL and 65XE both with Ultimate1MB,VBXL/XE & PokeyMax, SIDE3, SDrive Max, 2x 1010 cassette, 2x 1050 one with Happy mod, 3x 2600 Jr, 7800 and Lynx II
Approx 20 STs, including a 520 STM, 520 STFMs, 3x Mega ST, MSTE & 2x 32 Mhz boosted STEs
Plus the rest, totalling around 50 machines including a QL, 3x BBC Model B, Electron, Spectrums, ZX81 etc...
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