Repair fails - Motivation

[quadrant]

Have you ever attempted a repair, and ended up with things in a worse state than before you touched the object? If so, would love to hear about it.

Messed up a repair today, and feeling sad =/ Attempted to un-bend a plastic case (that had warped over time), using the oven method, and the poor thing twisted itself into a pretzel =// In hindsight so many things could have been done differently 

[masterx81]

Soooo many times 
Last one is a tektronik TD540 scope. I'm still fighting with it.
When thing goes to shit, i put it on ebay as not working and forget about it, else i freak out!
There is no success without failures...

One of the worst? A 32'' LCD monitor, years ago when they costed quite much. Repaired the psu, while remounting the lcd panel on the front bezel i've not noticed a screw between the bezel and the panel, so closing it have broken the lcd panel. Was at least 10 years ago. I still feel pain remembering it!

[elektrolitr]

I had very similar experience with the oven.

Buying a "new" car, I found that driver side mirror heating doesn't work (pretty much expected for a 4-year car).

I bought new mirror element and decided to repair the old one (because the mirror itself was flawless) with an ali-sourced heating element which costs about 1/30 of new mirror element's price.

Unglueing was a breeze, I heated the element in an oven for a bit and was able to peel off the plastic backing. It was a bit warped in process and I put it back in oven, hoping it will straighten by itself.

Then something drew my attention for ~10 minutes and after I returned to oven I found only small and chewy piece of plastic, about a quarter size of original support backing. Nothing to resque!

BTW, these chinese mirror heaters are nice, good quality PTC elements.

[PlasmaArcEng]

The inverter control board in my aircon split system burnt a track going to a step down converter. I had just power-cycled the unit a few times before hand so I assumed it was just a nasty shutdown that caused the burnout. I bridged the track and re-powered the unit. It went off with a bang as it vaporised the entire copper trace from the DC input terminal to the power transistor on the other side of the board.
I then had to replace a substantial number of components and do a lot of point-to-point wiring to get it going again. I also zapped myself on the large motor storage caps- always remember to discharge those when you are working on a VFD....

[WattsThat]

I know my limitations at age 64. They usually involve complex mechanical things, especially stuff like clocks and old slr cameras.

Most recently I bought a used B&L stereo microscope and it was so dirty internally it was unusable. I got it 50% of the way disassembled and I knew I would be in trouble if I disassembled the zoom mechanism so after just staring at it for a while, marveling at how it worked, I ended up running the lower optics assembly through the ultrasonic cleaner twice. Never touched the worm screws and moving optics assembly. Good as new and in service.

Yup, you’ve got to know your limitations 

[TheMG]

Doesn't exactly fall into the category of failed "repair", more like failed "maintenance", but anyways I used a compressed gas duster to blow years worth of dust out of a long neglected 2000VA double-conversion UPS.

Strangely, there was a blue glow coming from the circuit board after a couple of shots with the duster. Hmmmm, I don't remember ever seeing a blue LED inside the UPS, that's weird. It wasn't until I saw the smoke that I realized the blue light was actually arcs across the switching MOSFETs as they were self-destructing one by one. Should of disconnected the batteries before blowing the dust out!

[shakalnokturn]

I don't fook-up too often these days, besides I don't currently repair much for customers if all else fails I have the sledge-hammer / pickaxe option too take some of the frustration out of the fail.

A fail I do remember was while I was learning on CRT TV's:

I'd picked a nice (for the time) stereo multistandard set from the curb.
The fault was quickly spotted without specific tools, the flyback was leaky.
At the time I had no access to any service manuals or schematics, the TV of interest was a Telefunken 817 chassis, almost identical to the Thomson ICC5 chassis.
Having a few flyback transformers scavenged from ICC5's I fitted one in the 817 and powered it.
There was an intense crackling typical of the CRT charging to the EHT voltage followed by a rather large bang as I saw an arc through the CRT neck.
The EHT had gone so high that it perforated a hole through the CRT's neck through to whatever it was that was closest.

[goaty]

I did a repair on a small compact camera a while ago, lens was stuck with sand.
Took it apart which was very painful and the mechanic of the lens was complicated.
Cleaned all up, re-assembled everything and tested it before closing. Worked perfectly.
When screwing back on the housing, the screwdriver slipped and the previously charged flash capacitor....
(Was an old one with Xenon flash)

I literally threw the whole in the bin immediately. No point trying to repair as the control IC was COB.

[narkeleptk]

Messed up a repair today, and feeling sad =/

Happens all the time, no big deal just part of the process. Just remind yourself you can't make an omelette without breaking a few eggs.

[quadrant]

Doesn't exactly fall into the category of failed "repair", more like failed "maintenance", but anyways I used a compressed gas duster to blow years worth of dust out of a long neglected 2000VA double-conversion UPS.

Strangely, there was a blue glow coming from the circuit board after a couple of shots with the duster. Hmmmm, I don't remember ever seeing a blue LED inside the UPS, that's weird. It wasn't until I saw the smoke that I realized the blue light was actually arcs across the switching MOSFETs as they were self-destructing one by one. Should of disconnected the batteries before blowing the dust out!

Wow, that's narly! Didn't know dust could do that =$

[quadrant]

Thank you all for sharing your anecdotes Glad to hear that f*ck ups (sometimes very stupid/expensive ones) are part of the trade 

[bdunham7]

Just last night.  Trying to repair and reconfigure a ribbon cable interconnect with an unobtanium, glued-together locking connector on end and a normal header on the other, I was replacing the header.  I very carefully sliced off the cable as close to the connector as possible only to realize I had just cut off the wrong end!  I bagged everything up this morning and set the project aside for 'later'. 

[gordo51]

Have I ever....once trying to figure out why the ammeter side of a variable power supply was not reading properly shorted out something with multimeter probes and killed it. Face palm, a few curse words and put it under the bench out of site where it continues to gather dust. Will go back to it one day. If you can learn something from your failures that lessens the blow.

[ceoxrad]

Closely related

[EHT]

There's no kidding yourself when the magic smoke appears....

My first one when I was a kid: Family CRT TV not working properly, can't even remember what the original fault was. Connect scope to check something, smoke comes out of TV Live chassis, grounded scope Had to admit defeat on that one but it didnt stop me

Recently, diagnosed fault in speaker protection circuit of hi-fi amp, needed a special SMT transistor. In the meantime I though I'd use the amp.... speaker wires might have touched for a brief moment  Flames came out the top of the amp! Needed a lot more repairing after that but its good as new now.

The ones I really hate, as per recent post, are where you may well be able to fix it but the mfr doesnt want you to so you can't get certain key parts.

[SilverSolder]

Wife's older GM car had a failed electrochromic driver's door mirror (it auto-dims at night when it "sees" headlights).  Unfortunately, GM doesn't supply spare parts for this any longer.  I waited more than a year for one to turn up on eBay, after which I purchased it for much $.   To cut a long story short...  in the process of installing the replacement mirror, I managed to crack it...   all the electrochromic magic fluid drained out, the mirror became semi-matte and dark, worse than the one I had taken out...

It took more than 2 years before the next one turned up on eBay.  It cost even more $.  I gritted my teeth, bought it, and installed it wearing white silk gloves and a surgical gown...  successfully this time...

[james_s]

I don't fook-up too often these days, besides I don't currently repair much for customers if all else fails I have the sledge-hammer / pickaxe option too take some of the frustration out of the fail.

A fail I do remember was while I was learning on CRT TV's:

I'd picked a nice (for the time) stereo multistandard set from the curb.
The fault was quickly spotted without specific tools, the flyback was leaky.
At the time I had no access to any service manuals or schematics, the TV of interest was a Telefunken 817 chassis, almost identical to the Thomson ICC5 chassis.
Having a few flyback transformers scavenged from ICC5's I fitted one in the 817 and powered it.
There was an intense crackling typical of the CRT charging to the EHT voltage followed by a rather large bang as I saw an arc through the CRT neck.
The EHT had gone so high that it perforated a hole through the CRT's neck through to whatever it was that was closest.

There were some sets in the 70s (Zenith?) that were notorious for the HV going way high and arcing through the neck to the deflection yoke. Sometimes it would crack the neck completely off along with the yoke.

[narkeleptk]

I think this thread jinxed me. Shortly after my first post while working inside a power module I happened to just ever so slightly arc the 14V onto the mcu's 3V power rail with my dmm probe. Prior to this the module was somewhat working. She's dead as a door nail now. It is a pretty pricey module so I will probably fix it later but into the junk bin for now.

[garrettm]

I think we've all done some idiotic things while performing a repair.

I remember I was fixing a Fluke 8920A thermal converting voltmeter, turns out it had a bad filter capacitor. Okay so easy fix, fired up the solder sucker, slapped a new cap in and whammy it was working again. Ran some sanity checks and looked to be in spec. Then I went to put the thing back together. While investigating the meter I had removed some of the screws holding one of the internal boards so I could check under it for more electrolytic capacitors. As I was going to reinstall the screws one fell off the tip of the screwdriver and landed directly in the meat of the circuit. Turns out I had forgot to turn off the voltmeter... Upon realizing that fact, I turned it off and quickly pulled the screw out and reinstalled it. After firing it up again, I found it didn't measure correctly any more. Furthermore, I killed the one part that was unobtainum: the custom Fluke thermal converter IC. It's dead Jim. Angry, I picked up the whole thing and threw it in the trash.

More recently, I was refurbishing a plasma cleaner. The unit had a ratty power cord with a jacket so worn that the inner conductors were exposed. So I figured it was time for a new one. Grabbed my dikes and proceeded to snip the cord off near the strain relief. Turns out I had forgotten to unplug the damn power cord while testing the unit! God damn shit show proceeded to unfold as I cut through the cord. Interestingly, the breaker didn't trip during my hazardous short circuiting of the AC mains. Instead I plasma torched a notch in my cutters and coated the fuse holder and strain relief in a nice layer of copper courtesy of the plasma cloud fueled by the metallic vapor explosion. Turned a five-minute job into an hour long cleanup and search of a new strain relief. I also threw my newly modified dikes away in a walk of shame, I couldn't look at them and not think about how stupid I was.

Moral of the story, make sure you turn things off / unplug the power cord when performing any reassembly or disassembly.

[shakalnokturn]

Depending on configuration it's also worth discharging hazardous capacitors before reassembly too.
I've done damage once or twice neglecting that.

[IamSynthetiC]

Had a 40-year old amplifier my father had got from Paris on my bench. I had fixed it but was annoyed by the noise it produced. I was playing some music on it through my laptop and was scoping around. Then my hand slipped and the probe shorted a 30V rail to the audio output of my laptop  .
Burn component smell filled the air. Fortunately both of the devices are ok, my laptop sound card blew up. But the the fear of breaking one of the two was paralyzing.

[Zeyneb]

Christmas 2019: I was working on the electrical system in my apartment. I was working in the circuit breaker box. The upstream neutrals to the circuit breakers where tried together with a non-insulated U-shaped metal bar that was designed to be spaced at the circuit breakers width so providing neutral to the bottoms of a gang of circuit breakers. I was installing some new circuit breakers and laid some new wires in the box, all fine. The job was intimidating at first glance, never done it before. Just when I gained some confidence I wanted to measure the voltage to the live wires at the bottom of the circuit breakers. With the multimeter test lead I shorted live to neutral and then a big arc, bang and then darkness. The main apartment fuse had blown. Damn it, I screwed up. I had to think for a moment what would be the best way to deal with this situation. Ultimately I used my very nice neighbors electricity to get by in the evening, remember 25 december. The next day I was able to call the electricity net operator and a nice guy came to my house to install a new fuse.

Moral of the story: Even when intimidating jobs starts to look promising, don't get too excited yet. Pay meticulous attention at each step until you are completely finished.

[schmitt trigger]

A Sony Trinitron CRT TV, bulky and heavy.

Had to replace a burned-out a horizontal deflection transistor and several ancillary components.

Replaced them all, made all the linearity adjustments, put it all back together, and when I was moving it from the work table to its actual location, and my foot caught the hanging power cable, I tripped and dropped the TV into the floor.

My heart was shattered in as many pieces as the CRT was.

[shakalnokturn]

I crushed one unwillingly like that too, a customer's TV... embarrassing situation.
Once it was repaired I was carrying it down this quite steep and narrow single flight wooden staircase, something went wrong on the way, then there was a stone wall and cobbled floor just at the bottom.

Fortunately no cobble stones were damaged!

[jdragoset]

Once had a fellow engineer with a color TV CRT burned socket single connection who wanted to direct-solder a wire to the pin.
I advised that vacuum tube pin metal could not be soldered from previous bad experiences and  to and use a crimp sleeve.
Nope.
Watched it power up and work, loose picture and eventually see arc discharge inside CRT neck as the vacuum expired.
A really nice portable color TV as well.
That was about the time of the Challenger disaster.
I still don't give up and will cut, dissect, as needed to ferret out a problem and repair, rewind or bypass as needed to correct.
Sometimes aesthetics are not preserved but functionality is restored
(the ultimate goal)