It’s been a while since something broke, but that never lasts around here. This time our circa 2005 microwave decided to scare us. It started randomly staying on after the door was opened upon cycle completion. That was especially scary since it was hard to tell what exactly stayed on just by the noise.
Warning: Microwaves have lethal voltages inside, always unplug power when working on them. Proceed at your own risk.
Continue readingSeven years after the last teardown, we once again have an electric toothbrush that failed. Oddly enough the failure mode was exactly the same- top seal breaks, water gets inside, things corrode and battery discharges. This one was a week before the end of the warranty, so Philips was nice enough to send a new one.
This one has been sitting since the summer- it took a while to get all the rain to evaporate from the inside! When I grabbed the pour fella, it had water up to the mirror.
$1 takes it!
The latest addition to our vintage collection is a Keithley 130A handheld DMM from the mid-eighties.Keithley is not well known for its handheld DMMs, or at least I’ve never heard of them. It’s a 3.5 digit 0.25% instrument made in mid 1980s
Today’s teardown subject has been waiting for its turn for a while- I picked it up at the last Design East conference in Boston in 2012. There, Microchip and Energizer were talking about low power design and using these Schick Hydro 5 power razors as an example. Hot on the heels of my repair of a Philips Sonicare toothbrush, this seems to be a good fit for a comparison. Both things do essentially the same thing- they shake, light up some LEDs and not much else.
Schick Hydro 5
Another ebay find- a vintage Keithley 172 multimeter. The datecodes on the parts range from 1978 to 1984, placing the final assembly somewhere in mid-1980s. It seems fully functional, but could use a bit of a calibration to regain its past precision.
This unit was used for a few years with a very limited success until I finally got fed up and decided to peek inside. The always warm case and constant 7W power draw did not help its cause either. As one of the 2 star reviews on Amazon concluded- don’t bother buying one of these.
An ebay find made its way into the lab- an industrial quality DMM from Hioki, made in 1984! The meter has some pretty good specs as shown in this datasheet:
Today we are unpacking a brand new LCR meter from a company called Tonghui in China. It was purchased on ebay and took less than a week to arrive.
Chinese market packaging
Today’s quick visual teardown is of an 1984 vintage Keithley 197 microvolt DMM, Despite considerable age, it’s still quite alive and kicking and very useful for measuring low currents and voltages.
