Post your worthless and/or pointless repairs

[Doc38343]

Re: Post your worthless and/or pointless repairs

Here's another one to add to my growing list of fiascoes...

https://www.badcaps.net/forum/showthread.php?t=63537

[ratdude747]

Re: Post your worthless and/or pointless repairs

Dell Latitude Windows 7 Tablet. Screen had tab issues, whichI later found out cannot be fixed as nobody sells a proper screen that will work with the digitizer (after blowing $40 on said screen). I got the old screen to behave, only to find out windows 7 on tablets sucks (compared to modded 8.1) and the period Atom CPU is slower than a quadriplegic turtle (unlike modern Atom based tablets, which kick ass for what they are). It currently collects dust.

Also, a Panasonic CRT-based 1080i Projection TV with convergence issues. I redid all the resistors and convergence amplifiers (3 sets of IC's! $$$!), and still the convergence is dead. The kicker is that since then, I've curb scored two more slightly newer (with digital inputs) 1080i CRT projection units, and both of them work great w/o repairs.

There are many others, but those are the two worst $$$ vs result repair expeditions I can think of

[Dan81]

Re: Post your worthless and/or pointless repairs

Would repairing Deer PSUs be considered pointless? I did that once too...and later it failed again with a different problem. I junked it then.

Believe it or not I have tons of repaired Deers, from the worst to the best units.

I'd need an entire .rar archive to take pictures of them all and post it here.

[llonen]

Re: Post your worthless and/or pointless repairs

Not that I have any pics to show, and to me any paying customer repair is not pointless, but I did have to wonder about this Sanyo integrated stereo that recently came through the workshop. If anyone wants the details of model number etc I can look them up from my records, but this was the kind of stereo one can pick up at car boot sales for a few quid. The set had sentimental value to the customer whom was more than happy to pay the monies to have the system repaired.

[eccerr0r]

Re: Post your worthless and/or pointless repairs

I just got a dead 400W (sustained) sine wave inverter.
I wonder if this thing is pointless to repair. So far no obvious problems like char spots to focus at, so this will take a while to debug (and of course, no schematic...)

[eccerr0r]

Re: Post your worthless and/or pointless repairs

I lucked out on the AC inverter.

The symptoms were deceiving because the LEDs all blipped when switched on, as well as the power switch being a "soft" power switch. And the switching transistors looked OK.

Turns out it was just dead fuses (the fuses protected the transistors, how could it be, normally it's the other way around!) I swapped in some other fuses I had on hand and did some testing, seems to work just fine, at least when not at full load. Inversion efficiency seems to be on target. I was feeding in 13V 7A and got 73W out, not great but it's about right. I suppose I just need to get the right fuses and then this weak regulating 120VAC pure sine wave AC inverter will be ready for use once more. Weak 400W AC inverters seem cheap nowadays.

[Heihachi_73]

Re: Post your worthless and/or pointless repairs

I learned the hard way about replacing any and all similar caps with my Hisense TV. After replacing all of the bad Samxons and testing the others (all of which were perfect at the time, according to the ESR meter), in a few years the other Samxons went pointy on top and the TV went off, never to power up again. I replaced those only to find that the TV's standby LED still didn't come on - when the last of the Samxons went bad they took out a surface-mounted mosfet/voltage regulator or three with them, with one of them managing to melt its own solder and lifting itself partially from the board. Of course it was only after I had completely recapped the thing that I found those were also dead, making it truly a worthless recapping project!

The TV is still underneath my bed, although I doubt it is of any use to anyone now, even if the LCD panel, backlight and main PCB are still fine. It would cost more than a working second hand LCD to ship to anyone in Australia anyway.

[Heihachi_73]

Re: Post your worthless and/or pointless repairs

And it tried to bite me again, I just opened the remote to find that the batteries I had forgotten about had started to leak! Typical Chinese crap Duracell AAAs, of course. Only a Duracell would leak while still having 1.3 volts in the tank, any other alkaline battery might (yes, just 'might') leak after it's been drained flat or has negative voltage. How are they still in business again?

[momaka]

Wooden Handles for a Set of Cheap Screwdrivers

Hey, let's revive this thread again!

I found some cheap crap screwdrivers in one of my junk boxes. If I remember correctly, they came as a “giveaway” item waaayyyy back when I was still in robotics club in high school. Frankly, I thought they were thrown away. But when I was bored with my nephew one summer a few years ago, I decided to make a proper handle for these, as the original plastic ones were complete crap and all falling apart by themselves (besides, my nephew likes to watch me make more simple stuff like this.)

So first I got a piece of wooden dowel rod for the handle and cut two pieces to proper lengths. Next I drilled a hole through each wooden piece. Then, I put some shallow diagonal cuts in the screwdriver's steel bits so that the glue could adhere to them. For the glue, I actually used regular bathroom silicone/caulk, because that's what I had on hand. Finally, after gluing the steel bits in the handles, I stained the handles in dark Kona wood stain. The result (on the right side):



… not too shabby-looking. The steel of these drivers also didn't turn out to be that bad - actually better than some more expensive (but still on the cheap side) bits that a local store offered. I know it's still a worthless repair, but not that useless for me in the end - after all of that work, I actually started using these fairly often. And my nephew enjoyed (and even helped me) when I made these handles.

Now I need to make another pair of handles for the second set of screwdrivers seen in the above pictures (the ones where the plastic hasn't completely broken off yet). It may look intact, but that original plastic is so brittle that as soon as you try to unscrew something, the steel bit shatters it in half. But I'll save this job for a rainy day if I really have nothing else better to do.

[sam_sam_sam]

Re: Post your worthless and/or pointless repairs

Revive this post again

I had posted one on this forum awhile back

I have had some small switching power supply module that are sometimes not worth the time to spend to try to fix them

When this happens I just use it for parts

[momaka]

X-Acto 18xxx CN electric pencil sharpener

Another candidate item for this thread.

- An X-Acto 18xxx CN pencil sharpener.

Was told it makes noise when pencil is inserted but nothing happens. I tried it myself and surely enough, found out the same. More precisely, the motor ran, but the pencil sharpening mechanism didn't. So it's time to tear it open. But first, a label shot:
https://www.badcaps.net/forum/attach...1&d=1552457254

OK, now we open it.
https://www.badcaps.net/forum/attach...1&d=1552457254
https://www.badcaps.net/forum/attach...1&d=1552457254
I think the problem is pretty obvious here, no? Looks just like the motor gear got misaligned somehow and/or slipped.

With the motor out of the case, this is what its label said:
https://www.badcaps.net/forum/attach...1&d=1552457254
I'm guessing that first line (S01-16-12R01) is the model number of the motor. Speaking of which, motor is just a standard shaded pole type. It's made in 2012, so pencil sharpener isn't that old really. Only lasted 6 years, which is a little lame.

And here I took it apart a little further:
https://www.badcaps.net/forum/attach...1&d=1552457254
https://www.badcaps.net/forum/attach...1&d=1552457254
Some of you may have spotted what the problem really is now. If not, look at the white plastic gear on the motor again – not only is it misaligned, but it also has a small crack along its length. This explains why it was actually able to slip backwards. It didn't take much more effort to take off the gear from the shaft. My guess would be that either this white plastic isn't flexible enough (wrong type used) to be used on knurled shafts, or that the size/tolerances of the gear were a bit off. So when the manufacturer forced the gear onto the shaft, it probably cracked very slightly (or was stretched severely), making it fully crack over time / with use. I've noticed this before on cheap RC cars too, when I was a kid. The better ones always used either metal (brass) gears or high-quality ABS plastic.

Anyways… I noticed the knurled shaft made the gear have slightly more space between the teeth where the crack was, which made the gear run a bit “rough” when it engaged the large black spur gear in that spot. As such, I decided to sand down some of the knurling on the motor shaft.
https://www.badcaps.net/forum/attach...1&d=1552457254

After doing this, the gear was no longer stretched out, which meant the crack was also not as wide and thus made the gear engage smoothly again on the spur gear. Of course, now the gear definitely needed to be glued to the shaft to stay where it was. I decided “superglue”/”instant glue” (Cyanoacrylate) should work well enough. In retrospect, perhaps contact cement would have been a better alternative, as it is generally resistant to heat and oils. But I didn't have any at the time, so CA it was.
https://www.badcaps.net/forum/attach...1&d=1552457254

And then put everything back together:
https://www.badcaps.net/forum/attach...1&d=1552457254

After letting the super glue dry completely, I tested the sharpener – not only did it work, but it also ran a lot smoother than when the gear was cracked and stretched over the knurled motor shaft. So I gave it back to the owner. Hopefully it will last a bit longer now, but we will see. For a 30-minute fix, it was worth a try… though considering how cheap these things are thee days, even that much time spent on a cheap item like this is probably too much. But as always, it was fun for me. So cheers to another pointless repair!

[eccerr0r]

Re: Post your worthless and/or pointless repairs

Nice grats... I was wondering who uses pencils anymore (does anyone handwrite anymore?)...

I have a problematic shaded pole motor like the one you have, and I suspect that the rotor's "rungs" are no longer conductive to the end caps and thus doesn't spin anymore. Sigh.

[momaka]

Re: Post your worthless and/or pointless repairs

Nice grats... I was wondering who uses pencils anymore (does anyone handwrite anymore?)...

I use pencils almost exclusively when drawing/sketching almost anything. Got about a pound worth of them in a bag, most of which came back from when I was in middle school and high school - typically from people loosing them or just not caring to take them / pick them up when they dropped them. (And the hoarder in me always picks up free stuff that are still usable. After all, I *never* needed to buy pencils or pens because of that. Just erasers.)

I have a problematic shaded pole motor like the one you have, and I suspect that the rotor's "rungs" are no longer conductive to the end caps and thus doesn't spin anymore. Sigh.

Well, does it at least buzz? If not, check for an opened thermal fuse if it has one. Repaired a bathroom exhaust fan once that had this issue. Something got stuck in it and thermal fuse burned. Replaced and fan worked fine again. If that's not the issue, maybe drill out / cut away the existing shaded copper windings and replace with new ones (12-14 AWG solid wire??).

If not that... then maybe use the motor as an over-sized inductor?

[momaka]

Samsung 2 GB PC3-10600U RAM module

Here is another one… a Samsung 2 GB DDR3 PC3-10600U memory module, model M378b5673fh0-ch9.


I got three of these on eBay in a junk box with other PC parts. All were supposedly removed from a working machine (and they likely were.) However, I found one of the RAM modules didn’t work and would make the system hang when inserted with the others, no matter in which memory slot I tried it in.

Generally, I don’t try to repair bad memory modules. But I was feeling too lazy and bored to do anything else that day, so I started measuring some of the components on the bad RAM stick and compared their values to the good ones, as all three RAMs were identical.

And this is what I found:

… a cracked array resistor. It looks rather obvious up close like that with a magnifier in front of my phone’s camera. It wasn’t, however, even after several thorough inspections of the PCB. Goes to show why the multimeter is always your friend.
As for the mess around that resistor – it’s flux. I was about to remove it, until it crossed my mind to take a picture first.

Not surprised about the crack, as the shipping box was packed a bit poorly, allowing many of the parts to hit each other.

Position 1 pins (from left to right) on that array resistor had good resistance, as did positions 3 and 4: about 16.8 Ohms, as measured with my RS multimeter. But #2 is where the crack ran across and that resistor was open-circuit.

I found a 22-Ohm array resistor of the same size on a completely (physically) broken laptop RAM module I fetched out of a trash can many years ago. Desoldered very easily with my RS iron.

The soldering-back-on part was the hard one. After many attempts, I finally got it soldered on there – all by hand with my 30W Radio Shack iron again, mind you:


Why the RS 30W iron and not hot air?
-Well, I did try hot air – many times, as mentioned. But for whatever reason, my solder paste wasn’t doing any good and some of the pins on the resistor just wouldn’t solder no matter what (or they would bridge if I added solder paste again.) So I gave up and went back to my RS iron. I’ve done 16-pin TSOP ICs of the same pitch with it before, so I know I can do it. I just thought the hot air would be quicker and easier (NOPE!) Worth mentioning is that my RS iron has a copper tip that is very worn out. To its advantage, however, the tip is worn into a “spoon” shape with sharp edges – really perfect for fine SMD work, actually, as I’ve found over the years. With a steady hand, I was finally able to get that resistor soldered without bridging the pins… on the 3rd try. It’s always the middle pins that are troublesome – even the slightest extra residue of solder on the tip, and those middle pins will suck it up and bridge. The corners, on the other hand, are super-easy.

Anyways, I know this isn’t the prettiest job, and I even managed to get solder on the RAM pins. But the RAM module works just fine now:


Clearly, given the prices of DDR3 RAM at the moment, this isn’t really worth doing, unless you just have lots of free time. But as always, I like to reduce e-waste. Moreover, my DDR3 RAM inventory is quite scarce, so this RAM module will go into use, rest assured.

[stj]

Re: Post your worthless and/or pointless repairs

braid those pads clean,
i have seen bumps of solder damage connectors before now.

[eccerr0r]

Re: Post your worthless and/or pointless repairs

dang i could use some ddr3 ...
Have a DDR1 module IIRC that is also dead, wonder if i should check...

[momaka]

Re: Post your worthless and/or pointless repairs

braid those pads clean,
i have seen bumps of solder damage connectors before now.

Already done... though I filed down the excess solder (carefully!) rather than wicking it. Works all the same, though.

Have a DDR1 module IIRC that is also dead, wonder if i should check...

Worth a try, though I doubt you would find the same issue.
The one shown above was simply due to physical damage - i.e. stuff bouncing in the box they were shipped and banging each other.
However, you might have some luck with that DDR module if you first install a known working RAM in the motherboard and manually set the frequency to the lowest (maybe even relax the timing too, if it allows.) Then swap or add this module and see if the board POSTs. I have some lower-tier modules (like Patriot or AVANT, I don't remember) that are advertised as PC-3200 400 MHz but won't boot that that speed unless I lower their frequency to 200 or 266 MHz.

[eccerr0r]

Re: Post your worthless and/or pointless repairs

Yeah that module theoretically should work but is completely dead. Sort of makes sense that these boards get considerable mechanical stress on them though I don't think I need any more (whatever speed DIMM it is...) I need DDR3 and >=2GB DDR2

[Curious.George]

Re: Post your worthless and/or pointless repairs

dang i could use some ddr3 ...

What speed & flavor (U, E, F, R, etc.)? Sets of 2, 3 or 4?

[RethoricalCheese]

Re: Post your worthless and/or pointless repairs

Not really worthless/pointless repair but on Xbox One there was a pin shorted on the CPU. That short pulled NAND 1V8 low and thus the console was not powering on at all.

The fix was.. To cut the trace going to the CPU It started working and I haven't found an issue thus far. Everything seems to be working alright.