While working on my Lenovo 15ARH05 - the screen suddenly went blank, and the laptop wouldn’t boot anymore. Lucky that it failed on a Friday :)

After opening it up - I started checking for any shorts. It didn’t take me long to find the culprit. Pro tip: use diode mode. It will allow you to “home in” where the short is. Give it a try. Here’s a picture of the shorted cap - straight across the 19V rail, where power is being supplied to Vcore.. uh oh :) Can you see which of the two is cracked?

A colleague of mine asked me to take a look at his Makita work site radio. Completely dead. Not a single sign of life, not with any type of battery, and not with DC power input.

Makita has put the screws in the battery compartment in a very deep hole. And it requires a security Torx TX15 (Wera has a good one Model 05138269001 with a 300mm shaft). Once that is removed, you have to use a big hex bit to remove the screws that bolt the aluminium handles to the chassis. All that is left then, is to remove the bottom woofer grille, with 4 Philips screws. 2 screws are again hidden behind this mesh. Undo those, and we’re in.

The first thing I noticed was a bloated cap - C13. A 1000uF/25V “GD”-brand capacitor. An unknown brand to me, which I replaced with a (physically) larger 1000uF/63V Nichicon cap. Given that it’s quite close to the heatsink, it should fare better.

Something different to repair this time. My neighbor’s solar inverter suddenly stopped working. He already replaced it with a newer model, but would like to keep this one as a spare. So, he asked if I could take a look.

The first thing that came to mind is: how do I power this inverter. I need to test the DC side of this – and it needs quite a high DC voltage. I solved this by wiring two transformers back-to-back with a simple bridge rectifier and a smoothing cap. So it basically serves as an isolation transformer. But with high DC voltage, you need to be really careful.

So, testing with the DC voltage – dead. Absolutely nothing. Checking the filtering caps – everything looks fine, but nothing powers on the logic board. I get power until the transformer. And yes – visual inspection reveals there’s an issue with it: