Moto X4 power button failure (part 2)

Remember how my Moto x4 had a power button failure after 10 months of ownership? Well, the replacement x4 phone that Motorola shipped me had its power button fail in the same way after only a month of usage. Luckily, I still have a month of warranty coverage, and their customer support representative again waived the $24.99 “Premium” fee to ship me a replacement phone before I ship them back the broken one (with a $200 deposit.)

However, I’m not at all impressed with the hardware quality of the power button on this model. I think I will have to just set the screen timeout to a small number of seconds and stop turning the phone off with the power button. (It already has a swipe to activate feature so you don’t need to use the power button to turn it on…)

DIY Thermo-Electric Cooler prototype

I have been playing around with building a DIY Thermo-Electric cooler. Yes, I know the TEC’s are horribly inefficient when compared to a compressor based refrigerator. And I know you can buy basic TEC micro-fridges for $20-$50 online.  We have a camping van that has a small odd sized hole that doesn’t quite fit any of the commercially available car/van coolers, so I’m investigating building my own. This post will discuss prototype number 3.

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Moto X4 power button failure

I’ve had a Moto X4 phone since November of 2018 (I bought it new from Google Fi) and recently the power button started failing intermittently.  Reading forums on the internet, having power buttons fail on phones is now a “thing”. Apparently phone manufacturers are cheeping out on the physical buttons to save money? Seems like a bad part to have fail.

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A certification mark isn’t everything…

I recently purchased a WorkZone Wall Mount Power Board (with detachable tool holder) as an impulse buy at my local Aldi (WorkZone is the Aldi brand for household tools). I needed more light, I could use a power strip, and I liked the fact that each outlet had its own switch so that I could turn on/off battery chargers depending upon if I was using them or not.
workzone wall mount powerstrip with lights and detachable tool holder

The lights worked well, it included a nice template for placing the screws to match the slots in the back and everything was going well until I tried plugging in one of my battery chargers. The outlets were super stiff on the first plug in (not unusual for new outlets), but then they just started to feel dangerously loose. They didn’t appear to grip the plugs well or make good electrical contact. For a device rated at 1875 watts, this was concerning to me.

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Installing Garage Door Slide Locks

My garage has four doors (two in the front, and two in the back) which gives a lot of cross-ventilation potential, but unfortunately some of the doors had the slide-locks installed incorrectly, such that there was no available slots to lock the doors in a “slightly open” position to let air circulate.  They also only had one lock per door, so I rectified that situation by adding a 2nd slide lock to the other side of each door, and moving a few of the original slide locks so that two of the doors can be locked with a 2″ gap below them.  I spent less than $30 for all four slide locks and a box of self drilling sheet metal screws, so it was a relatively quick and inexpensive improvement.

DIY 4×8 Floating Dock section

My last 8×8 floating dock section was built from mostly salvage materials. I’m slowly adding sections until it reaches shore. Unfortunately, I can’t use the cylindrical foam floats as the base of walkways, as they will rotate/spin in the water. (Also, I have plans for the other 2 cylindrical foam sections….)

Two sections of floating dock on lake

So this 4×8′ section of floating dock uses two commercial roto-molded dock float sections (48x24x16″), which drove the price up to around $680 in materials. (But I have a decent number of composite deck boards and hardware left for the next (3×12′) section I plan on building.  [Yes, every section of my dock will have a different width, deal with it.]

 

 

 

TaoTronics LED Floor Lamp indicator light circuit bend

I bought a TaoTronics LED Floor Lamp from Amazon which has three different color modes (half the LED’s are warm white, the other half are cool white, and you can pick either or both banks together) and allows you to dim the light (which might be needed, as it’s quite bright at full power). Because it uses LEDs, it only draws 10-12 watts for a lot of light output, and you can convert it to a desk lamp just by unscrewing the two extension tubes. Overall I’ve been very happy with it.

The only complaint I had was that the standby indicator light that lights up the power switch to make it easy to find at night was white instead of red, and slightly brighter than I liked. (Most people wouldn’t mind at all, I’m especially sensitive to light at night…)

So I opened the control panel of the lamp by unscrewing four screws in the back and pulling the front piece off. There is a steel C channel that goes from the purple tube screw at the bottom to the gooseneck at the top which I had to take out (3 screws at the top and bottom) to get access to the circuit board.

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BEME ERod motor drive unit failures

I have purchased three BEME Erod motorized drape systems (one in a previous house, and two in the current house). They have an infrared (IR) remote control that allows you to open and close the blinds at a push of the button, which is very useful if you have things in front of the blinds that make it hard to access the window, or if you just want to be able to open or close your blinds without getting out of bed.

Two of these units have worked flawlessly for several years. My third unit however has had two separate failures which I suspect may be due to poor quality parts.

The first issue crept up slowly, starting out as an intermittent delay in closing. The blind motor would make a “click” when you pressed the close button, but the motor would not engage for 20-60 seconds. Over time, the delay got longer and longer until eventually the blind refused to close. (Although the relay inside would still click when the button on the remote was pressed.)

Diagnosing this as a relay contact failure just from the sounds it made, I opened up the unit, found the part number on the relays, ordered replacements and (for good measure) replaced both relays. (I bought 5 of the relays, so I’m all stocked up for future relay failures.)
two blue relays on a circuit board.

When I had the unit open, I noticed that there was one extra red “re-work” wire on the circuit board, indicating that the PCB had a problem (either a trace left out of the design, or not correctly connected on the PCB during manufacture.) and had to be repaired at the time of manufacture. This is actually more common than you might expect on inexpensive consumer goods, and since the motor was working well with the new relays, I closed things back up.

Around six months later, one night with no prior warning, the motor failed to respond to the remote control completely. No clicking, so the problem probably wasn’t the relays.

Here was my diagnosis procedure:

  • I tried the remote on my other erod (despite the fact that the red light was lighting up when I pushed the buttons) to make sure the remote was working.
  • Because the motor unit was acting as if it was not receiving any power (completely dead), I took the power adapter and tested to make sure it was providing power by using it on my other (working) erod.
  • Now that I had determined that the problem was definitely with the motor unit, and not with the power supply or remote, I disassembled the motor unit.
  • I checked the fuse on the circuit board, as it is the first possible reason power might not get into the circuit, but it was fine. (Also, a small yellow LED on the circuit board was dimly illuminated when plugged in.)
  • I visually checked the capacitors to make sure that none of them were leaking.
  • Since I had a diode tester mode on my multimeter, I checked all the diodes (but didn’t really expect them to have failed….)
  • At this point, I noticed something funky on the circuit board. A small black component had one of it’s legs replaced by a resistor.  (You’ll probably have to zoom into the photo to see it.) Normally, if a resistor is called for in a circuit, it will have its own location on the circuit board. This resistor was definitely added in later in the manufacturing process, and was not part of the original circuit board design.  Since I hadn’t found anything else that would explain the failure, I felt that investigating this part was a good idea.

78L05 power regulator with a resistor replacing it's input leg

  • The part is a 78L05 linear power regulator, which steps the 12v input down to  5 volts suitable for powering the microchips that watch for the IR remote control signal and trigger the relays (via transistors).  The small yellow led was illuminating on the board when power was applied, so the 5 volt power rail should be working….but, the whole resistor leg looked dodgy to me. When I measured the voltage coming out of the 78L05 regulator, it was only 2.7 volts!  (Just enough to illuminate the LED dimly, but not enough to run the other ICs.) After looking up the spec sheet to make sure that it wasn’t a 3.3 volt regulator, and really was supposed to be outputting 5 volts, I knew that either the power regulator was faulty, or something farther into the circuit was drawing so much power that it was not able to provide the proper voltage.
  • I de-soldered the output leg of the power regulator from the rest of the circuit, and the output voltage went up to 5 volts, which hinted that the problem might be farther into the circuit. However, when I tested how much power the regulator could provide, it would only drive 17mA into a short! (A good regulator should provide 100 or 150 mA of power.)

  • I wasn’t sure if the resistor on the input leg was limiting the current that much, so I took the whole thing out and tried powering the regulator directly by bypassing the resistor, and it had the same low output current issue.
  • So, time for a new 78L05 power regulator. This is a VERY common 5 volt regulator, and I happened to have one in-stock, which I soldered back into the circuit. I considered leaving in the input resistor (520 ohm), but decided against it, as the original circuit schematic obviously didn’t have that part, and according to the spec sheet, a 78L05 should be able to go from 12v down to 5v without problems. I measured the idle current draw of the entire motor unit afterwards, and it was only 8 mA, so the voltage regulator is dissipating 12-5 = 7 volts at 8mA, or 0.056 watts (5.6 mWatt) continuously, which is trivial even without a heatsink.

My suspicion is that the factory substituted an “off-brand” (or even counterfeit) 78L05 power regulator which they knew would have trouble dropping 7 volts, so they put a resistor in front of it to drop some of the voltage/power external to the power regulator, but the cheap part still failed.  I’m hopeful that I have now replaced all of the parts that are likely to fail in this unit, and perhaps it will work well for me in the future.

 

 

Do you need to clean your solar panels in Florida?

Living in Florida, we get a lot of rain that does a good job of keeping our solar panels mostly clean. To see if extra scrubbing was needed, I cleaned 1/2 of my solar panels after they had been installed for 11 months using a scrubbing brush and dish detergent.

The panels that I cleaned went up in power production by an average of 0.11 kWh/month. [0.11 kWh * 36 panels * 12 months = 47.52 kWh of extra power over an entire year…assuming the cleaning effect persists after the first month.] So this is a very small amount of power (about $6 worth at 13 cents per kWh.) in return for an hour of scrubbing. [And this assumes that the cleaning benefit lasts for a full year, which may not be the case.]

 

I would suggest only scrubbing your (Florida) panels every few years unless you notice a drop in performance.

 

You can download my data and simplistic analysis in the attached open document spreadsheet: SolarPanelCleaningExperiment