Fixit Log

What skills to learn, what tools to get
Sclass
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Location: Orange County, CA

Re: Fixit Log

Post by Sclass » Sun Aug 25, 2019 12:18 am

I’ve recently had to upgrade my iphones. A number of things like moving from CDMA to GSM and also the power consumption on my iPhone 4s handsets drove me to the iPhone 6s. The hardware has been quite good. It’s the software that seems to get outdated. My iOS 9 Safari won’t even show modern website content. The battery life is too short due to inefficient chips. And worse, Apple is only releasing the new iOS 13 for iPhone 6s and up. So my gut feel is there will be a lot of perfectly good phones sitting unused in drawers soon.

Sad. Unsustainable. But we cannot keep using tube TVs forever. The new tech is amazing and powerful. Unfortunately it comes at a great energy and environmental cost. I don’t think the typical phone user understands just how much refinement goes into a smartphone. That refinement comes at a great cost and it gets washed away in 24 months contracts between upgrades.

tonyedgecombe
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Re: Fixit Log

Post by tonyedgecombe » Sun Aug 25, 2019 2:23 am

I’m not sure phones have that much of an environmental cost, compared to running a car, flying, eating beef, owning too much house.

I want to extract as much value as possible from mine whilst minimising costs but I don’t feel particularly guilty about owning it.

bigato
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Re: Fixit Log

Post by bigato » Sun Aug 25, 2019 6:14 am

Just to play devil's advocate here, but we don't really need smartphones all that much, do we? Considering all that it has been shown to do to our brains, I'm seriously considering not replacing my iphone SE once it dies.

tonyedgecombe
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Re: Fixit Log

Post by tonyedgecombe » Sun Aug 25, 2019 6:22 am

bigato wrote:
Sun Aug 25, 2019 6:14 am
Just to play devil's advocate here, but we don't really need smartphones all that much, do we? Considering all that it has been shown to do to our brains, I'm seriously considering not replacing my iphone SE once it dies.
I used to think that but if I look at the number of services I access through my phone now I think I would miss it. However I don't do Twitter/Facebook so perhaps I avoid the worst aspects.

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Bankai
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Re: Fixit Log

Post by Bankai » Sun Aug 25, 2019 6:47 am

@bigato: are smartphones doing these things to our brains or are we doing them ourselves? I think they are but a tool and it's our responsibility to use them responsibly.

I see my smartphone's main benefit in how it replaces several other devices (dumbphone, MP3 player, watch, camera, kindle, laptop/tablet etc.). Also, having access to the internet almost anywhere is very useful.

bigato
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Re: Fixit Log

Post by bigato » Sun Aug 25, 2019 7:10 am


Sclass
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Location: Orange County, CA

Re: Fixit Log

Post by Sclass » Mon Aug 26, 2019 1:07 pm

tonyedgecombe wrote:
Sun Aug 25, 2019 2:23 am
I’m not sure phones have that much of an environmental cost, compared to running a car, flying, eating beef, owning too much house.

I want to extract as much value as possible from mine whilst minimising costs but I don’t feel particularly guilty about owning it.
I don’t have a good idea either. It’s just a feeling I get when I look inside a phone. There is a level of integration, refinement and beauty that just cannot come out of nowhere. Entropy thermodynamics law forgot the exact one. I visualize a river of guck sloughed off to produce the shiny little object in my hand that looks so nice and clean.

Once nice thing about repairing is I get to see how Apple puts things together. They are by far the cutting edge in assembly from their system on chip microstructure to their novel materials. We used to dream about the stuff in PowerPoint back in 2000. Now it’s sitting right under my microscope. Size is misleading.

I think this stuff may have a bigger impact than we can imagine. But I may have to visit a Congolese cobalt mine or a fab in Shenzhen making facial recognition dot projector ICs before I’m sure.

Sclass
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Re: Fixit Log

Post by Sclass » Sat Sep 28, 2019 9:35 pm

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Changed a set of brake pads tonight on one of my cars. The great thing about Duralast pads from AutoZone is the lifetime guarantee. You buy them once, they record your car and log you into their system by your name and phone number. When your pads wear out you go in and buy another pair. Change out the worn pads and return them to Autozone and they’ll give you a 100% refund. You basically get free brake pads after the first set.

They’re pretty cheap pads at $20. The assumption is you’ll sell the car before you need a new set and not pass on the warranty info. Luckily I drive the same kind of car I since 2002.

Kind of a sales gimmick but it basically gives me free brake jobs since I do my own work. I live on a big hill and wear out brakes every 2.5 years on my daily driver.

paretotime
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Re: Fixit Log

Post by paretotime » Fri Oct 04, 2019 11:33 pm

Changed the door swing on our fridge to be right handed instead of left handed. It was placed in the kitchen in such a position that the door opened to the hallway, and not towards the counters and food prep area. Makes a huge difference in our food prep flow now that it is corrected. The only problem is that the fridge had possibly been switched before and a few of the screws were glued in. With prying all came apart and back together except for the lower door handle screw which had to be sheared. The handle was temporarily held on by just the top screws which might have been fine with some adhesive, or a new screw hole drilled in - but before I could do that it was pulled in a moment of hurry and the door handle broke in 2. So sad, the main fix was $0 and less than an hour to change over the freezer and fridge doors. The handle replacement is $96 for the lowest I can find it online. I'm going handle-less so far and it works fine. Might keep it this way.

Sclass
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Money saving fixes

Post by Sclass » Sat Oct 12, 2019 11:23 pm

Routine battery replacement on my smartphone. These kind of repairs on iphones go from $25 at the mall kiosk to $70 at Apple Store. I get these chinese batteries on ebay. This one cost me $7 and it included a bunch of tools like plastic pry tools, a pentalobe screwdriver, a phillips screwdriver,a suction cup to lift off the glass. Instructions on Youtube. Fifteen minutes saved twenty dollars and a trip to the mall. Just follow the steps online. Some of the newer phones are more troublesome by design. My iphone 6 was easy. Had a sudden business trip and I didn't want my phone going dead on me now that we use the phones for boarding, taxi and comms.

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So I've been watching YouTube videos on this clamping tool called Clamptite that makes hose clamps out of wire. I thought it would fit here because it is a cheap way to make hose clamps. Conceivably you can make cheap and good hose clamps once you buy their expensive tool. I have a bunch of garden hose scraps at my place that need splicing with barbs. Coyotes keep chewing holes in the hoses and I have to remove sections. I was thinking this was a cheap way to do repairs.

https://youtu.be/3NXVnmMjFk4

There are a bunch of people making their DIY versions of this tool using cheap hardware store parts. I threw one together for $4 after watching this video.

https://youtu.be/I3g7-qBDAGY

So I went ahead and made this tool. I actually made two. One to keep in my car with some wire in case I needed to fix a water hose or fuel hose on the fly. Here is what I came up with. I kind of flipped the Russian design upside down and 3d printed a nice knob (remixed from Thingiverse) for the top. Made some nice clamps. I didn't double up the wires like the videos. I am primarily using it for low pressure emission control plumbing on one of my cars that needed some PCV modifications.

an almost free clamp. takes a little fidgeting to get it together. the wire is basically free. I have hundreds of feet lying around left over from projects and scavenged from the trash.

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My version of the tool.

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tightening wire by spinning the knob.

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locking the wire by bending it over.

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You can get the wire quite tight. The bending over part adds additional tension. The wires really dig into the hose. I actually broke some wires by being over zealous.

detail of the tool tip

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My opinion is the tool makes really nice low profile clamps. Screw clamps stick up too much. I don't like how long it takes to actually "make" the clamp. But you're basically getting a clamp almost for free. A big spool of 40 mil stainless steel wire costs $8 at Harbor Freight. Face it, it is cheap but you have to do a little work.

At least I didn't have to buy the tool from Clamptite which ranges from $30 - $60 depending on the model/material.

Coming up, some electronics repair. I have discovered a new tool called a T7 electronic component tester. Basically a little $15 device from China ebay that will interrogate parts, figure out what they are and tell you what their parameters are if they are functioning. I'm still working on the debugging technique because it is unlike classical electronic troubleshooting where you understand the function of the device, use schematics and trace a fault from end to end. This little thing allows you to pull suspect parts and do a go/no go test on them. Then I swap in new parts when I find a blown part. Not sure if this is an effective method yet. Stay tuned.

/SaoJR3]Image[/url]DIY: transistor tester kit (open source) by linux-works, on Flickr

Sclass
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Location: Orange County, CA

wire binder V.2

Post by Sclass » Sun Oct 27, 2019 3:35 pm

So I wasn't terribly happy with the feel of my wire binder shown above. It felt floppy in use and didn't feel stout unless there was a lot of tension in the wires. It bothered me for a bit and I came up with this little plastic bushing to fix the slop. No more floppiness at the expense of a little of its pull range. I tested it out and it still has enough tension range.

The dog bone shaped nut was made on the 3d printer. The tolerances were too tight but I just heated the part up in situ using a heat gun for 30 seconds and it loosened right up. Works great now and restricts the unwanted degree of freedom.

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Detail of guide nut. The use model of the printer is different. I spent twenty minutes at my cad station designing it. Then six minutes printing it. It is kind of upside down compared to the old way of finding a piece of stock, scribing, drilling and filing at the vise till I get the desired part dimensions. Feels more like word processing and I now can make more by hitting print multiple times. I ended up making two. One for the shop and one for the car.

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SavingWithBabies
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Joined: Mon Aug 31, 2015 2:50 pm
Location: Midwest, USA

Re: Fixit Log

Post by SavingWithBabies » Sun Oct 27, 2019 6:48 pm

My 3d printer is still my hammer. I bought some cheap old shelves with some built in drawers on a lower part and the old MDF had bowed out towards each side. End result is the draw sliders were pulled outwards maybe 2-3mm which was enough to allow the drawers to fall down off the roller wheel. I could fix this quite easily with other material. Perhaps some cardboard or paper? Or washers? But there were some downsides to washers in that I wanted to fix the problem once and for all (at least until it bows more) and washers wouldn't support the full 1" or so width of the slide brackets.

So I printed out some 1.6mm plastic squares with holes in the right places. That fixed it right up and the drawers no longer fall down. I wasn't sure if I'd need the full ~3.2mm so I divided it but it turns out with just one side with the spacers, the fit is great so I went with that. They look like this:

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Printed in gray (this is the larger spacer, other one is at rear of slide bracket):

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On the other hand, I had a loose broomstick from a short broom I'd cut down for use in the RV (that we're now using in the apartment). And I debated 3D printing something but I ended up using hot glue as that was a more pragmatic solution. I could have found another material and cut it to size for these spacers but printing gave me precise dimensions and I could just print some more once I was sure I had it right (and I was free to go do something else while waiting for the print to complete).

SavingWithBabies
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Re: Fixit Log

Post by SavingWithBabies » Sun Oct 27, 2019 7:24 pm

@Sclass I like the wire hose clamper tool. And I've debated one of those testers. I haven't bought one yet but I recently would have liked the ability to test some capacitors. Have you tried it for that yet? Seems like a very useful tool.

Unseelhilr8
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Re: Fixit Log

Post by Unseelhilr8 » Mon Oct 28, 2019 6:13 am

That's really awesome.

Sclass
Posts: 1675
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Location: Orange County, CA

Re: Fixit Log

Post by Sclass » Mon Oct 28, 2019 7:29 am

The tester post is coming up. The tester works well for what it is. Certainly good enough to check the functionality of components. I recently had he chance to test half a dozen variants and they work about the same. The price difference is the user interface.

Works great on caps. Make sure to discharge the cap first. You can burn out the tester if you have a high voltage across the terminals.

I’m having some trouble with my new blind debug process. The hope was I could go into a broken device, start individually testing suspect components without any knowledge or documentation of the circuits function, then replace the defective part and thus repair the item.

It’s not quite working out. I’m good at fixing things where I have a diagram and knowledge of the theory of operation. Then I systematically go from one end to the other to find the fault using things like a voltmeter, power supply, signal generator and oscilloscope. I wanted to try to get away from this style and develop a fault tracing technique that relies more on the cheap tester than actual understanding. Kind of like using a Tricorder.

Stay tuned.

Sclass
Posts: 1675
Joined: Tue Jul 10, 2012 5:15 pm
Location: Orange County, CA

Re: Fixit Log

Post by Sclass » Wed Nov 06, 2019 10:12 pm

So I’ve been working on this climate control amplifier in my Mercedes. My hope was that I’d fix it by testing for bad components using the cheap tester. The tester works quite well. I found several capacitors that were out of spec and three damaged transistors. Unfortunately it took a heck of a long time to do this because the parts needed to be desoldered from the board. After I put everything back together, my car AC still didn’t work. Worse, sometimes my heat would turn on full blast even when I was calling for AC. My compressor was on so the AC and heater just worked against each other. I created a different set of symptoms by only fixing parts of the circuitry.

As I dug deeper through the system I realized the fault was no longer in the amplifier but in a switchboard on the dash. I took that apart and reheated old solder joints and cleaned up the boards. Still no luck. I don’t really understand how the circuit works and I don’t have schematics. My hope was I could find questionable stuff with the tester and I’d replace it.

Well it just didn’t work out as planned. I gave up tonight after hacking on this thing a week. It turns out there are some electromechanical parts that are falling apart. I don’t know where to buy individual components to replace them so I ended up buying new Mercedes parts to fix the car. :(

Didn’t save much money on this one. The new push button box cost me $250. Hopefully this is where the problem lies. I’ll post up some photos of the process. I basically went after things that fail. In order of common failures,

1) cracked solder. Sometimes called “cold solder” this is usually the result of thermal cycling on high current solder joints. After awhile the solder joints cracks. The fix is reflowing solder with a soldering iron. This often can be visually detected.

2) old electrolytic capacitors. These leak, swell or just dry out. The capacitors in this circuit are for the analog computer that regulates cabin temperature. So delays and integration is off when the caps go bad after thirty years. I did find bad ones and I changed them.

3) bad output amplifiers. Transistors on the output often go bad. They’re heavily loaded and they see the bulk of the thermal stress. Basically I check every part of the circuit connected to something off the board. So these transistors control the solenoids and motors on the air flaps and hot water valves. One was out of spec and it happened to be discolored indicating thermal stress.

4) bad input amps/preamps. These see signals coming in from off board and can also get damaged by fault conditions up stream. I couldn’t test these on my board using the tester but you can check the voltages between the inverting and non inverting inputs to see if they are close to 0 volts indicating stable regulation. Unfortunately parts off board are often part of the control loop so the failure can cause a railed amplifier yet be far away in another subsystem. Regardless, I had some LM324s in a junk box so I swapped out the LM2902s. Somewhat downgraded in performance but I don't think it'll matter.

Ok, well I’ll post up some photos of the fun. It was a negative result. I’m not sure if this debugging style is all that great. It certainly did not work well on this one. I made my final conclusions to replace the entire HVAC controller after I obtained a wiring diagram online and started trying to understand the theory of operation of the system and its components. Not quite what I’d set out to do. Originally I wanted to fly blind and let the tester guide me.
Last edited by Sclass on Wed Nov 06, 2019 10:44 pm, edited 1 time in total.

Sclass
Posts: 1675
Joined: Tue Jul 10, 2012 5:15 pm
Location: Orange County, CA

Re: Fixit Log

Post by Sclass » Wed Nov 06, 2019 10:33 pm

the board
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tools: soldering braid, solda-pult and a soldering iron (not shown)
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remove components from board
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testing
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tester didn't work on small inductors and capacitors. they basically aren't there as far as the tester knows.

22pF in other words not really there.
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burned heat sink on a transistor. I pulled transistor and its gain is below spec. damaged

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Some various tests. Inductor, bicolor LED showing two junctions. MOSFET

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very small inductor

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