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ADR modules part 2, to recap or not?

Electrolytic capacitors have a wet dielectric which degrades with age and temperature. As a result the extremely thin oxide layers may become less isolating when stored over decades. Either the capacitor shorts or opens at some point, or just doesn't perform as good when it was new. Re-capping is the usual procedure to replace (all) electrolytic caps in restoring old audio equipment. The most common coupling capacitor value in these modules is 15uF / 40V. These smaller values might be replaceable with solid foil capacitors, though it largely depends on the space on the circuit board if this is possible and the cost involved. High-end audio nut cases (no relation to this blog) may spend top dollar/euro/yen on such things. Here it just has to be in line with the actual value of these units. So we will only use foil if the costs are limited. Otherwise just stick to cheap but good quality electrolytic caps. The likes of Nichicon, Panasonic, Vishay. Vishay bought a lot of the old Eur...

Kruishout - Marking/Scratch Gauge

And Now for Something Completely Different: the kruishout (Dutch), or you might know it as a marking or scratch gauge. This is an essential measurement tool in woodworking! Note the sharp needle or point on the left side of the beam. This is used to scratch a line in the wood. This specific one was from my grandfather. He was a carpenter specialised in making ship interiors. Carpenters can own multiple of these gauges on a project, so they only need to set them to a specific size and have less work re-adjusting constantly. Some variations may even use the tip of a knifeblade to actually cut a deeper line, e.g. when the grain is too strong to make a proper straight line. Or to actually cut very even widths of veneer. The Japanese or Chinese variants seem to use the knife tips. I’m not so much into woodworking at the moment, but this surely is a keeper! It’s also fairly easy to make some of your own. If you know a special use of this tool other than most uses shown on youtube, please...

A Story of Repair (SoR): Electric Kettle

One or two weeks ago, during the day, the RCCD (residual-current circuit breaker) tripped. The root cause was very unclear at first since no equipment was switched on or off during the event. Also the weather was quite humid and sticky after a thunderstorm, so that could be a factor as well. By unplugging some usual suspects one at a time, we could trace it to the culprit. First I unplugged the coffee maker from the mains, but again the RCCD tripped after some minutes. Next the electric kettle was unplugged, and bingo! The RCCD did not trip again. This Kettle, a Tristar HL-108B, has a base piece. This base did have my suspicion, since the inner wires became visible from where there should be a cable strain relief. Opening the base required special spanner or ‘fork’ style screws. Somehow they want to discourage repair, but they are wrong. With a suitable long bit style drivers it was fairly easy to get access to the wire terminals. The multimeter did not show any problems, but these kin...

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