Murphy Thread - Page 1
Forum section: electronics / general

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 23, 2018, 11:56:19 pm
content: Today we petition for the murder of Murphy and his constant attempts to thwart everything.How hast thou been thwarted? (Preferrably technical wise)Small screws are the first candidate, evil little bastards... Not only do they get lost, they get stuck, and it's hard to find an extractor small enough. And it's always after you've taken something most of they way apart...

author: Electro Detective
author_rank: Super Contributor
timestamp: March 24, 2018, 12:08:47 am
content: You forgot the poor quality soft screws with forced stripped heads in a pita location...compliments of the OS below -mates rates- paid WonHungLo assemblers

author: wraper
author_rank: Unknown
timestamp: March 24, 2018, 12:17:32 am
content: Usually this happens like this. I'm 1-10 thousands km away from home, repairing some laboratory equipment. The thing is already fixed but it has something that don't need fixing right now but may potentially break later. So I think, heck, I don't like it leaving like this, I'll make it right. As the result, I remember yet again road to hell is paved with good intentions. In the process of doing right, something breaks, screw thread get stuck, some fitting breaks. And now I'm in situation to figure out how to get out of this crap and leave the thing at least going for now without having spare parts to replace. Like gold plating on glass tube in IR measurement cell got partially stripped off, let's replace a resistor in amplifier to get more gain as mitigation. Often superglue is your best friend.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 24, 2018, 01:10:00 am
content: Quote from: Electro Detective on March 24, 2018, 12:08:47 amIt happens with high-end stuff too. Set screws are the worst, especially buried super deep in a hole.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 24, 2018, 02:12:57 am
content: Carbon resistors!If you can get to them, and change them easily, they're all all fine.If you can't...they're all dead.

author: BravoV
author_rank: Super Contributor
timestamp: March 24, 2018, 02:22:00 am
content: Alkaline batteries, when you do constantly and diligently checked them, they never leak.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 24, 2018, 02:27:56 am
content: When they do leak, if it's not important, it'll just be a bit of green dust. If it's important...it's all rusted away.

author: wraper
author_rank: Unknown
timestamp: March 24, 2018, 02:34:06 am
content: Quote from: Cyberdragon on March 24, 2018, 02:27:56 amI got to purchase a whole new back cover for my Keysight U1272A because of this.

author: Electro Detective
author_rank: Super Contributor
timestamp: March 24, 2018, 09:05:38 am
content: and I can assure all fellow battery victims here that it makes no difference how expensive and great quality the batteries are,Murphy issa no far away...

author: Red Squirrel
author_rank: Super Contributor
timestamp: March 24, 2018, 09:49:24 am
content: I have a server that controls my home automation stuff and also provides monitoring. About once or twice a year it just randomly fails, and has to be rebooted. It's still running, but it loses network connectivity. EVERY SINGLE TIME it happens when I'm not home and I'm trying to remote into it. Of course the whole server dies when I'm on vacation or other place where I'm relying on it to get any alarms. I almost need to setup a monitoring server for the monitoring server.Speaking of batteries, if you have a Wii or other console with remote/controller that takes alkalines and you don't play it a lot, check them.

author: tautech
author_rank: Super Contributor
timestamp: March 25, 2018, 03:37:24 am
content: TH component lead snippets.Before powering ON always rotate/invert the DUT and listen for Murphys little creations rattling around inside.Tinkle, tinkle and a hunt for them is always better than poof/bang !

author: Electro Detective
author_rank: Super Contributor
timestamp: March 25, 2018, 08:41:02 am
content: Second vote for clipped component leadsassisted by rogue blobs of solder, sometimes both from day one when the unit was manufactured and someow passed inspectionTipping the unit upside down and around, plus a few love taps and a blast from an air gun or vacuum cleaner in blow mode ~usually~ sort of sorts that outand freaks out the snooping neighboursI had two DUTs on two different occasions, different models but same manufacturer, the models known to be 'temperamental'both had small metal staples rattling inside (the office stapler type), that I found after a total disassemble,both units never again had issues and no other fault foundI actually suspected staples the second time around and hit instant pay dirtI can only imagine some assembly line fwits stuffing about shooting staples at each other during lunch break, because nothing else makes sense

author: SeanB
author_rank: Super Contributor
timestamp: March 25, 2018, 10:32:34 am
content: I would more assume that there is paperwork as the unit passes through the assembly process, and the stages as completed per meter or small batch are stapled to the previous paperwork, using a regular office stapler. Thus the occasional jam and clearing of the jammed staple, with it going who knows where, probably into the pile of partly assembled units in the bin. Really common thing to have happen, staples get into the most amazing places.

author: Ampera
author_rank: Super Contributor
timestamp: March 25, 2018, 03:31:06 pm
content: They say that no man has ever assembled a computer fully, and had it turn on fully working the first time. Whoever claims to have done this is a liar.I've had many 5 minute "This shouldn't take too longs" turn into several hours of anger, frustration, and eventual defeat, especially with my older computers being stupid.Probably the biggest instance of Murphy's Law I've had is while I was giving the first attempt at building my Pentium Pro computer about a year ago.I got the board, DOA. Nothing worked, and I spent hours trying to get it to do anything. Then, after a day of wasted time and frayed nerves, my only capable machine, an i7-4790k box, the board popped. No big deal, it's under warranty, except the warranty doesn't cover complete jackasses who forget how to install an LGA socket cover, resulting in me having a nice MSI-Z97 PCMate board with a not so nice LGA socket, and no way in hell I'm getting a new one.b r i l l i a n tThis doesn't end, oh no, because despite me having to slap together an Athlon 64 X2 5000+ (yes, that was my second best machine) into my machine to have my SSD probably being smacked to hell and back with memory swapping (it's still here, though), I had to go on vacation the VERY NEXT DAY.b r i l l i a n tSo I have to leave returning the Socket 8 board to someone else, since I was going to be gone longer than I would be willing to wait for that sort of thing. The vacation went alright, despite knowing I had to buy a new board when I came home, all the while suffering with a CPU and board from 2006. I come home to find my keyboard's (musical) LCD had fractured (the readout that shows all the instruments and such). So, after all that stupidity, I have two broken boards, a crippled workstation, a broken keyboard, and I'm out 80 bucks for a new Z97 board.b r i l l i a n tfriggin Murphy.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 25, 2018, 05:09:08 pm
content: /\ expected replies..."you killed it 'cause you didn't use wriststraps...naaaah"I opened some super cheap Chinese POS audio something-or-other and found a ton of loose screws of different sizes rattling around inside, stuck to the speaker magnet, and stuck in blobs of gross cheap glue...

author: Ampera
author_rank: Super Contributor
timestamp: March 25, 2018, 10:04:06 pm
content: Lol. The Pentium Pro board did actually turn on, it just didn't post. It had a somewhat old flash memory chip on it that I think might have just died.Now about the time I had 3 dead boards in a row, each of which slightly less dead than the other....

author: g.lewarne
author_rank: Regular Contributor
timestamp: March 26, 2018, 12:40:41 am
content: replaced dozens of laptop screens, never an issue.Need to replace mine, badly scratched.Order panel 1. Panel arrives. Drop panel before even fitting it, cracked.Order panel 2, successfully transport it to my "operating" table. Screw it into laptop. Screwdriver cams out of the teeny tiny screw and gouges across the panel.Order panel 3, successfully transport it to my table. Sucessfully screw it into laptop. Turn on. DOAOrder panel 4, successfully transport it to my table. Sucessfully screw it into laptop. Turn on. 3 bright green pixels.I give up at 4 and leave it as it is.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: March 26, 2018, 06:10:01 am
content: Bench rule #26:Any small object (such as a resistor or screw) when dropped on the floor immediately attempts to run/hide under something.

author: basinstreetdesign
author_rank: Frequent Contributor
timestamp: March 26, 2018, 06:33:33 am
content: I built an L/C meter a couple of years ago to test the value of a bunch of inductors once. I went through three versions of hardware including design, home-brew pcb fab, assembly and firmware re-writes for various reasons.All versions had to be made from parts on hand including the uC- no purchases. I had 3 types of uC that I could use.#1 ver ended because all 4 of my uC type #1 were found to be dead. But to fix them I had to get a schematic from the company that made my device programmer. I found they were (almost) out of business due to a fire they suffered a few years earlier and lost ALL engineering info on the products (including mine) they had then. So I had to fix it with no schem.#2 ver ended when I found the SW just would not fit into the 2K code space of the uC type #2,Half-way through ver #2 the HDD on my XP laptop that I was using to develop it, died.I had to replace it, re-build all of the SW installations on it and re-establish the license for the SW IDE. The IDE re-installation made me the most nervous as I had to get in touch with the SW company that sold it to me 10 years prior and talk them into sending me a new installation license code even though I had never bought any maintenance from them in all that time.#3 ver was successful but need complete HW and SW redesign for the only other uC type I could use, a ATMEGA16 with 8K code space.After all that, about 4 mo into it, I came face-to-face with the impossible prospect of calibration. And there I was stuck but the best I could do is get it to within about 10% - but that was good enough for me - then.I wrote an instructable on the experience to show what can happen when things just WILL not go right sometimes. It's here:https://www.instructables.com/id/InductanceCapacitance-Meter-Saga/

author: Mr. Scram
author_rank: Super Contributor
timestamp: March 26, 2018, 07:51:52 am
content: Quote from: basinstreetdesign on March 26, 2018, 06:10:01 amSmall objects are subject to quantum physics and can therefore blink in and out of existence.

author: Ampera
author_rank: Super Contributor
timestamp: March 26, 2018, 12:53:48 pm
content: I've dropped tensioners for lockpicking on the floor, and it took an embarrassing amount of time to find them again.

author: Cyberdragon
author_rank: Super Contributor
timestamp: March 26, 2018, 03:11:31 pm
content: Quote from: Mr. Scram on March 26, 2018, 07:51:52 amOr they get stuck to your pants so you never find it until it randomly falls off...or you sit on it.

author: schmitt trigger
author_rank: Super Contributor
timestamp: March 26, 2018, 03:30:09 pm
content: When you drop to the floor THE VERY LAST small (sub-0402) SMT component in your inventory...... and which to boot, has an oddball value like 7.865K at 0.1%Then you are all in your hands and knees, wondering how much tiny debris accumulates on the floor.

author: IanMacdonald
author_rank: Frequent Contributor
timestamp: March 26, 2018, 03:47:26 pm
content: There have been attempts to deal with Murphy ranging from pointed sticks to a Russian surplus RDS-220Invariably, something goes wrong with the weapon. I guess that's the advantage of being Murphy.

author: Electro Detective
author_rank: Super Contributor
timestamp: March 27, 2018, 09:39:05 am
content: Quote from: Cyberdragon on March 26, 2018, 03:11:31 pmOh yeah, that scenario, been theretoomany timesSo now my 'seek' inventory includes:a bright torchsoft brush broom and small brush/shovel kitlarge magnet in a sockcheap cyclonic type bagless vacuum cleaner with transparent collection bin, kept in a clean stateand if all that fails to find the 'runner'...I close my eyes and drop another small object that isn't vital to proceedings, in the vicinity of where I think the runner ran to,go looking for runner #2prayingI find runner #1or both...or NONE,and move on !!!and shout Murphy a beer for his hard work

author: TerraHertz
author_rank: Super Contributor
timestamp: March 29, 2018, 01:07:10 am
content: How about that time I thought "Hmm, I haven't made a backup image of my main working hard drive for a very long time. I'd better do that now. But first, I'll just make some small tidy-ups of the folder structures. Will only take a few minutes.During those few minutes, the hard disk suddenly became a totally unreadable non-disk. Bricked. Hardware failure on the logic board.That was when I found out that with modern drives you cannot just swap over an identical control PCB from another same model HDD. Because they have factory set calibrations in the firmware, and will not work at all on any physical drive but the one they were calibrated for.

author: Electro Detective
author_rank: Super Contributor
timestamp: March 29, 2018, 11:57:23 pm
content: Quote from: TerraHertz on March 29, 2018, 01:07:10 amOuch, I didn't know thatgood ol ' 'progress and innovation' to keep up with modern MurphyismI'll do a straight up 'untidy' drive to image or backup clone from now on, and worry about the file and folder housekeep after it's done

author: Mr. Scram
author_rank: Super Contributor
timestamp: March 30, 2018, 04:24:47 am
content: Quote from: TerraHertz on March 29, 2018, 01:07:10 amSome modern drives. Tiny version differences can ruin your day too, though.

author: SeanB
author_rank: Super Contributor
timestamp: March 30, 2018, 05:44:03 pm
content: Done the board swap. Lucky I had a donor board with same firmware version and only a few serial numbers apart as donor for the cloning, then I put the board back, as the person whose computer it was had nothing to do but catch up on her filing. Drive was for something that was no longer supported officially by the supplier, and they had no longer any media to reinstall. Made 2 copies though, then swapped the boards and put the donor back in the machine. It worked on both sides, and I grabbed another drive to make the second copy, and wrapped it up in some antistatic bag and bubble wrap, and popped it into the case as a spare.Murphy dictated I never needed that second spare, though I did then make monthly full backups of the drive, though as it was running Win98 that was fine, only a 40G drive, the giant zip file was easy to store and compressed well, seeing as the data was almost all text files with predictable structure. I still have Win98 media to reinstall, complete with the COA and the DVD, all still shrinkwrapped, 2 copies........ Then another 2 DVD's with every single patch Microsoft ever offered for Win98, including all service patches up till EOL.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 31, 2018, 02:02:31 pm
content: Those dropped small items don't run and hide. They turn transparent for some short interval. Proof is that after the unit you are working on has been buttoned up with some kind of work around the part will be found laying there in plain sight.

author: jordanp123
author_rank: Regular Contributor
timestamp: March 31, 2018, 02:52:30 pm
content: Had one just yesterday in fact, a buddy has a commercial garage door opener for his garage, said opener quit and he asked me to look at the board. After about 20 minutes of looking at it, tracked it down to a failed PIC uController , as soon as it gets power its a dead short circuit on the chip. Called the company that makes the units, "Sorry sir we don't sell individual IC's", Okay fine, ask them about just buying a new board "Sorry sir that board is EOL, we don't have any units to sell you......", asked if they had any kind of universal boards, "Yes, sir we do but none that fit that model, its the oddball in our lineup".So he has a commercial unit with everything working perfectly except a dead chip that is socketed.

author: Vgkid
author_rank: Super Contributor
timestamp: March 31, 2018, 03:59:08 pm
content: When using any power tool , be sure to know where all cords and hoses are. Was using the table saw , and managed to cut an air hose and cut into the saws power cable. It was not the blade , but the drive belt .

author: Mr. Scram
author_rank: Super Contributor
timestamp: March 31, 2018, 06:39:52 pm
content: Quote from: Vgkid on March 31, 2018, 03:59:08 pmThat's a classic.