Electric lawnmower repaired yet again

In Vaccine vested! I reported

I also took apart the lawn mower to see it if is fixable.  As always, it took me a long time to clear out the grass packed into the recessed screw holes to get the cover off, and a long time to vacuum all the grass out of the interior of the mower.  When I did finally get access to the motor and electronics, I determined that the bridge rectifier had failed again—this time with a short circuit instead of an open circuit.  I’ll buy another GBPC5010-G‎ 50-Amp bridge rectifier, and see if this one lasts a little longer.

There is one mistake in the quoted section—the first failure of the lawnmower (back in 2017) was also a short circuit.  The new behavior was identical to the old.

When I got back from Berkeley today (where my wife and I were visiting our son), I found the rectifier and a couple of other packages that had been delivered on Friday sitting on our porch.  I took apart the lawnmower and replaced the bridge rectifier.  I verified that the old rectifier really had shorted out two of its diodes, so I was pretty confident that I had fixed the problem and I put the mower back together.

It still didn’t work.

There was no longer a short circuit that blew fuses, but the mower just ran for a few seconds and died, as if the blade were blocked.  With the mower unplugged, I could turn the blade by hand, but took the opportunity to chip some of the dried-on grass from the bottom of the mower anyway.

After removing the cover again, I inspected the motor more closely, and I decided to take off the top plate of the motor (which holds the brushes), to see if there was anything wrong with the rotor or commutator.  The commutator looked very dirty, and it looked like the carbon from the brushes (or perhaps some carbonized grass) had gotten stuck between adjacent plates of the commutator, so I scrubbed the commutator with an old toothbrush.

After I reassembled the motor I tested the mower without replacing the cover—it seemed to work ok.  I replaced the cover, and lawn mower worked just fine.  I was too tired to mow the lawn (very little sleep last night, and the trip back from Berkeley had taken 6 hours, rather than 3 hours, because of BART delays, the BART train we were on going out of service, and missed connections), but I should be able to mow the lawn sometime in the next week.

Incidentally there was another error in Vaccine vested!: the 500 is a “Rapid bus”, not light rail.  It does provide a pretty quick connection between Diridon station and the new end of the BART line at Berryessa. It was also free, because VTA is not charging for transit until April 1.  I could have ridden the Highway 17 Express for free also (because I’m old), but I just took their half-price offer for regular passengers.  I did use my new senior Clipper Card on BART for the first time, though only on one leg of the trip, as I had some money on my old regular Clipper Card to use up.  The whole round-trip to Berkeley cost only about $17, which is about what it would cost me with all the senior discounts.  I don’t plan to take senior discounts on the local buses (SCMTD really needs the money), but I will take them on BART and VTA, which have a much bigger and wealthier tax base.

Santa Cruz County hits 200 Covid deaths

A while back, I posted about the Santa Cruz County Health Department’s COVID-19 dashboard.  Yesterday, 2021 March 23, the county hit 200 COVID-19 deaths, so I thought I would update the post.  We have been doing a little better in the nursing homes—now only 51% of the deaths are there (102/200) instead of 66% (79/120). The four big outbreaks are the same, with a couple more deaths at Watsonville Post Acute, and on more at Hearts and Hands, but Sunshine Villa is close behind with 7 deaths and many of the other nursing homes now have 1–4 deaths.  Statewide, the fraction of deaths from nursing homes is about 23% (down from 33%), so we are still way overloaded with nursing-home deaths.  Or, more cheerfully, we’ve been better about keeping down deaths outside the nursing homes.

As before, most of our positive tests are in young adults, but most of the deaths are in older adults—the case fatality rate starts going up somewhere in the 60s and really soars in the 80s and 90s:

age range	cases	deaths	case fatality rate
0–9	1085	0	0%
10–19	1865	0	0%
20–29	3122	0	0%
30–39	2649	4	0.15%
40–49	2232	6	0.27%
50–59	1878	5	0.27%
60–69	1269	27	2.13%
70–79	611	42	6.87%
80–89	339	61	17.99%
90+	195	55	28.21%

The case fatality rate is very slightly higher in each age category, which may be due to the California strain that circulated in January and February being a bit more deadly.

I’ve been looking at the lagged case fatality rate (dividing the number of deaths by the number of cases 2, 3, or 4 weeks earlier) on http://91-divoc.com/pages/covid-visualization/.  The 4-week lag seems to give the most constant case rate, but even it shows a pretty big increase in California in the last month—the cases now seem to be more deadly.

Although the case rate still indicates that more Latinx people are getting infected than their share of the population (55.98% of the cases are Latinx vs. 33.49% of the population),  the death rates match the population statistics (35.5% of the deaths are of Latinx people).  Most of the old people in the county are white, and age is a much stronger predictor of who will die than race is.

I can’t check the number of hospital beds, because the state moved the page and the county has not updated the link.  The forwarding link provided on the state page goes to Alameda County, not Santa Cruz County, and I don’t see how to fix that.  From the information that is available, we seem to have hit peak usage around January 16, with about 85 hospitalized, and we are now down to around 5 hospitalized—so we’re pretty much out of this spike.  Let’s hope that a large enough fraction of the population is vaccinated before we get hit with another spike.

Vaccine vested!

Last Friday marked two weeks since I got my second shot of the Moderna COVID-19 vaccine, so I’m now as immunized as I’m going to get against the SARS-COV-2 virus. My wife got her second shot of the Pfizer vaccine, so we are both fully immunized.

We can now go wild! We’re planning to take public transit! to Berkeley! Our current plan is to take the Highway 17 Express (currently half price), then the 500 Express light rail to Berryessa, then BART to Berkeley. I was just getting used to Warm Springs as the bus connection, instead of Hayward BART, and now Berryessa is the transfer point. Who knows—before I die BART may get all the way to Diridon station!

If we somehow miss the 500 express, we can take the Amtrak Capitol Corridor to Berkeley instead, but Amtrak does not take the Clipper Cards (though the supposedly sell them on the Capitol Corridor).  The scenery along the Amtrak tracks is a bit more interesting than along the BART tracks, though.

I got my grading for Winter quarter done last night (two days before the grading deadline), so I finally get a “weekend” after 10 weeks of working 7 days a week.  I do have to put together my syllabus and set up Canvas for my two classes that start on Monday, though, so I can’t get a full week of break.

For my “weekend” I started by putting a new bike computer on my bike.  The old Cateye Enduro 8 finally failed (replacing the battery didn’t fix it), and I bought a new Cateye Velo 7 to replace it, as the closest current equivalent.  The cables and brackets seem cheaper and flimsier than the old ones, so I don’t expect this bicycle computer to last as long.  Most of the bicycle computers on the market seem to be wireless ones, but I really don’t like the idea of having twice as many batteries to replace, shorter battery lifetimes, and lower reliability of wireless units.  I considered getting a cheap Chinese bicycle computer that had a fancier display than the Velo 7, but decided to stick with a name brand that I know has been pretty reliable.

I also took apart the lawn mower to see it if is fixable.  As always, it took me a long time to clear out the grass packed into the recessed screw holes to get the cover off, and a long time to vacuum all the grass out of the interior of the mower.  When I did finally get access to the motor and electronics, I determined that the bridge rectifier had failed again—this time with a short circuit instead of an open circuit.  I’ll buy another GBPC5010-G‎ 50-Amp bridge rectifier, and see if this one lasts a little longer.

Forty-eighth weight progress report

This post is yet another weight progress report, continuing the previous one, part of a long series since I started in January 2015.

I’ve poked into the “overweight” territory for the first time in my life—it is not where I want to be.

 

There is a clear pattern of New Year’s resolutions over the past few years, but this year there was not a big dip.

My exercise has been very limited, but I don’t know how limited, as my bicycle computer failed—even replacing the battery did not revive it.  I’m going to have to buy a new bike computer, I guess.

I got my lawn mowed today—well, almost.  The lawn mower failed just before I finished.  It’s different from the failures I’ve reported on before (and here and here) in that this time it tripped the circuit breaker every time I tried to restart it.  So I’ll have to take the mower apart to find the short circuit.