Gas station without pumps

2021 April 24

Electric lawnmower repaired again and again

Filed under: Uncategorized — gasstationwithoutpumps @ 14:47
Tags: , ,

In Electric lawnmower repaired yet again I reported

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.

I did mow the lawn the next week, but about halfway through I started having trouble with the mower.  The motor ran fine, but if I squeezed the handle all the way it turned off again, making the mower rather difficult to control.  I finished mowing the lawn, but decided to investigate the problem.  At first, I thought that there might be a mechanical problem, with the handle releasing the switch when pulled too far, but I saw no evidence of that when I disassembled the handle and looked at the action of the cam on the handle.

Using my multimeter, I determined that the switch operated normally when the button was pressed part way, but not when the button was pressed in all the way.  I suspected that this meant that the switch was damaged (perhaps by corrosion), so I ordered a new switch.  Unfortunately, the part is quite expensive (about $15 on eBay), because it is a custom-made switch for Black and Decker.

I ordered the switch, and ebay said it had been shipped. I thought that the Post Office had reported it delivered, but I never saw it.  I even asked the mailman about it two days after the claimed delivery, but he could not remember.  He thought he had stuffed a thick envelope in the mail slot, but wasn’t sure.  So either the post office did not deliver, or porch pirates had taken the package. [See update below.] Both outcomes seem to be likely here, based on reports on Nextdoor.

I ordered another switch which was shipped on 4/20 and arrived on 4/22.  Today, I installed the switch.

switch-connections

The old switch, showing how the wires were connected. I took this picture before disconnecting any wires, in case I needed a reference for where they went.

new-switch

The new switch, showing the part number. I transferred one wire at a time from the old switch to the new, so I didn’t need the reference photo that I took.

new-switch-in-handle

The new switch in place in the handle.

old-switch-insides

I disassembled the old switch to see if the contact damage was visible. The problem was not corrosion but burned material on the contacts—probably from the short circuits from the earlier rectifier failures.

I’ll try out the mower again this afternoon, to see whether this latest fix does the job. So far I have bought two bridge rectifiers, one set of brushes, and two switches to lengthen the life of this mower. At some point (perhaps at the next failure) it may be worth getting a new mower.

Update (still 2021 April 24): I mowed the lawn with the repaired lawnmower, and it worked fine. While I was mowing, the mailman came, with the package that had the first switch I had ordered. I went back to the USPS site to find out what had happened.  It turned out that the ebay package that had been delivered was one for my wife, not the lawnmower switch.  The switch had not arrived at the post office for ten days after the company (Parts Sales) had said they had shipped it.  So the missing switch was neither the post office’s fault nor was it porch pirates—it was due to lies by the company claiming they had shipped when they hadn’t and confusion on my part about what package had been reported as delivered.

2021 March 28

Electric lawnmower repaired yet again

Filed under: Uncategorized — gasstationwithoutpumps @ 19:55
Tags: , , , , , , ,

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.

2021 March 23

Vaccine vested!

Filed under: Uncategorized — gasstationwithoutpumps @ 13:41
Tags: , , , , , , ,

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.

2018 June 22

Repairs: kitchen sink and lawnmower

Filed under: Uncategorized — gasstationwithoutpumps @ 15:48
Tags: , , , ,

Now that my grading is done for the year and all my grades are filed, I finally have time to take care of some chores around the house.

One of the first chores was to fix a slow leak under the kitchen sink.  It has been there for a year, and I believed that the leak was coming from the adapter between the faucet (which had ⅛” female pipe thread) and the sprayer hose (which had ¼” female pipe thread).

The first thing I did was to try to shut off the water to the faucet (not that I really needed to, since the faucet valves were still working). The quarter-turn shutoff valve seemed a little stubborn, and when I pulled hard on the lever, the whole pipe broke, spraying water all over the kitchen.  I ran out to the whole-house shutoff and managed to shut the water down with only about 2 gallons (8 liters) of water to mop up.

The pipe snapped right next to the body of the shutoff valve.

Some idiot (most likely me) had attached the brass shutoff valve directly to the steel pipe, with no intervening galvanic break, so there was a lot of corrosion due to galvanic currents.

Inside the valve and the pipe the corrosion was rather extreme.

So I went down to the hardware store and got a new shutoff valve, a CPVC nipple to replace the steel one (thus getting the necessary galvanic break), and a replacement for the adapter.  The hardware store did not have ⅛” MPT to ¼” MPT, so I ended up getting ⅛” MPT to ¼” FPT and  ¼” MPT to  ¼” MPT.

I put in the new shutoff valve and reassembled the faucet-to-sprayer connection.  The new shutoff worked fine, but the sprayer hose connection leaked worse than before.  It was now clear, however, that the leak was coming from the ¼” MPT-to-hose connection, and not earlier in the system.

I went to the hardware store again to get a new washer for the hose.  I was sold a 00 faucet washer, though I was bit dubious that it would work.  Sure enough, when I assembled hose connection it just squeezed the washer into the pipe, and the connection leaked as badly as before.

So I went back to the hardware store again and bought a whole new sprayer with hose.  I would have replaced just the hose, but the sprayer I had did not have a detachable hose—or rather, the hose was detachable, but neither end of it would pass through the sprayer hose guide, so I needed to replace the hose and the hose guide, at which point it was cheaper to replace the whole thing.

I replaced the hose guide and the sprayer, tightened up all the connections that I had just made, and the leak seems to have stopped.  One chore down!

My next chore was to fix the lawnmower again (see Electric lawnmower repair and Electric lawnmower repaired again).  There were two problems this time: the extension cord was not making good contact with the plug for the mower and the lawnmower blade was very dull.

Sharpening the lawnmower blade was pretty easy: I took the blade off with a crescent wrench, and brought it inside to grind on my wet wheel.  I could not get the curved parts of the blade that way, so I clamped the blade in a vise and used a half-round file to do those parts of the blade.  The mower blade is a fairly soft steel, to keep from chipping or shattering when it hits stones or other hard objects, so it sharpens quickly but doesn’t take a very sharp edge. I did manage to make it sharper than the rather rounded, dented edge it had before.

I determined that the problem with connection to the extension cord was with the cord, not the lawnmower, by the simple expedient of trying a different (shorter) extension cord, so I went to the hardware store (again!) to get a 15A replacement socket for the end of the extension cord.  I cut off the old socket, stripped the wires, and attached the new socket.  After verifying that I had connected everything correctly (using a standard 3-neon bulb socket tester), I checked out that the lawnmower worked with the fixed cord—it seems to be fine.

Another two chores done!

Tomorrow, when electricity is cheaper, I’ll try mowing the front lawn, which has gotten a little shaggy.  The back lawn is probably not mowable (the grass is over 3 feet high), and will need chopping down with a weed whacker before I can mow.

In between the faucet repair and the mower repair, I tried replacing the wheels on my son’s rolling luggage.  The wheels appear to be 76mm diameter wheels with standard skateboard bearings.  I went over to Skateworks on Soquel Ave, but they said that the wheels were too narrow for skateboard wheels, and recommended trying the wheels for inline skates (which they do not sell).  Rather than wander all over town looking for rollerblade wheels, I ordered a pair of cheap ones from Amazon (hard ones for outdoor use—durometer 89A), which should arrive on Monday.  With any luck, I’ll be able to cross another chore off my list then.

2018 February 4

Electric lawnmower repaired again

Filed under: Uncategorized — gasstationwithoutpumps @ 21:30
Tags: , , ,

In Electric lawnmower failed again, I reported

My Black and Decker electric lawnmower (model MM1800 type 1) failed again in December, and I finally got around to taking the top off today to look at it.  … The switch and power connections were all working correctly, so I think the problem now is that the brushes for the motor have worn down to the point where they no longer make contact with the commutator.

A new pair of brushes for the mower costs only $9 (https://www.amazon.com/gp/product/B00J5S3PDC/), so I think I’ll replace the brushes and see if that fixes the mower.

The new carbon-block brushes arrived over a week ago, but I was grading all last weekend, all week,  and most of this weekend, so I did not get a chance to install them until today.

The old brushes were attached to the wires from the bridge rectifier with a crimped connector that I don’t have a replacement for, so I just cut the braided wire from the old carbon block and soldered the new braid to the old one.  It only took a few minutes (because I had not replaced the screws in the lawnmower cover yet—getting those screws out is what takes all the time), and the mower worked fine afterwards.

I mowed my front lawn and the mower seems to be fine again, though I need to replace the end of the extension cord, as the waterproofing insulation is beginning to crack.  I think I need to sharpen the mower blade also, but that may have to wait for another break in the grading—maybe I’ll have time in a couple of weeks, when we have a long weekend for Presidents’ Day.

The grass in the lawn does not grow much in January, but the oxalis has gotten quite lush and is starting to bloom. The nasturtiums in the back yard are taking over where I removed a lot of blackberries (though they won’t bloom until April or May, if this is like other years).  Lots of other things on our block are blooming from roses to magnolias, but pollen levels are supposedly low or moderate. The acacia trees on Bay Drive seem to be blooming earlier than usual this year, and they are a major source of tree pollen in this area—I’ve not seen the yellow carpets of pollen on the road yet, so I think that acacia flower buds may not have opened yet.

Next Page »

%d bloggers like this: