What's the weirdest fault you ever fixed?

[rdf]

FM processor feeding a live FM transmitter. All the room equipment input/outputs route through a passive balanced jackfield. Picture a '30s telephone operator, same jacks and cords. All the sources are wired properly in phase left/right. The processor's input is wired in proper phase left/right. All the patchcords are wired in correct phase. Stereo source 1 goes to air in phase, stereo source 2 when jacked into the processor goes to air ... in mono.

Drove me nuts for better of a morning. Jackfields of that vintage were hand assembled at the factory. Wires were soldered to each panel jack and terminated on multi-term block euphemistically called a christmas tree. The user side showed consistent wiring colour codes on all solder terminals, however the jack side was a liquid lunch special. The processor's input jacks were factory cross wired between jacks, and the same done to the adjacent source 1 jack pair, in such a way that the wiring errors between processor input and source 1 canceled in normal use.

I like AES-EBU.

[pheonix358]

Man, Port Moresby, 1974!

Was up there on school holidays, my sister was working up there and got me a job interview in an electronics repair and sales place. Owner hands me four parts, a BC109 four lead transistor a resistor, a capacitor and an in4001 diode. He says, "Do you know what any of these are?" I identified all of the parts including values and correctly indentidied the fourth transistor lead as a shield lead for the metal can. All he said was '****.' He yells out to his partner and we repeated the test. The partner said "Christ, your hired." Adult wages about twice what would be paid in Aus for a technician. Cool!!!!!!!!!!!!!!!!!, I was 17.

First job was a HMV Triton radio Cassette. No sound! Checked unit over and by using the bench speaker I decided both speakers were dead. Both???

The Prime Minister had been making a speech, the chiefton got upset and threw a spear to take out one speaker, the PM jumped to one side (Unit was running dual mono), when the PM took no notice another was thrown. I found (and still have somewhere ) the two stone heads from the spears. Hardest part was understanding pidgeon English.

Many more stories from that 10 week job.

Terry

[Serge66]

Greetings,

I was troubleshooting a simple circuit: a voltage comparator feeding a counter/divider by ten.
With a 1 kHz input signal on the comparator there was no outptut on the counter. Comparator output ok. Easy! I thought. I replaced the CMOS divider. And tried again. Strange, I should have had a 100Hz signal. But the frequency was nowhere near 100Hz. I thought that maybe I had zapped the CMOS. I replaced it again taking care to ground myself during the handling and soldering of the IC. Switch on. Mmmmh! still not didviding by 10. I replaced the chip once again. Same problem. Somehow, I decided to clean the flux off the board with methylated spirit. When the board was dry, I switched on again. It worked!!!

Keep it clean.

Serge

[thermal runaway]

Not a particularly tricky fault , but one I enjoyed a great deal of satisfaction from solving.
My girlfriend at the time's Mother had a car which would cut out intermittently and sometimes dangerously , like when pulling out of junction. She had taken it to 3 dealers all of whom had replaced parts and charged obscene fee's. She had also called out the emergency repair service she was a member of 4 times and none had found a fault. I had offered to have a look a few times but she was skeptical of my skills because I didn't work in that field. Finally one day she had announced she was going to sell it for whatever she could get and be done with it , my GF said please let me have a look. She reluctantly agreed.
During all the time this was an issue I had already worked out it was almost defo electrical and decided to go for the simplest thing first. The only pattern that was evident was it would happen typically during the warm up cycle from a cold start , so I started her up and waited for the cut. Sure enough she cut , so I deployed my secret weapon , freezer spray to the electronic ignition module ! Satisfyingly that was it !! As soon as the module was cold the engine would start , warm it up with a hairdryer and it would cut. I was hailed as a genius and had extra special 'attention' from the GF for weeks !!
The Mother went back to the main stealer who last looked at and failed to solve the problem and gloatingly announced that someone who actually knew what they were doing had sorted it and she was never going to buy another Vauxhall again due to their incompetence.

[jackinnj]

Originally posted by thermal runaway
and she was never going to buy another Vauxhall again due to their incompetence.

MB Techs tell me that they never figured out the problems with the first series of E-Class wagons. They would die at stop signs, mine blew out 3 NAV systems. The car would refuse to unlock when the weather was hot. I think that the specified mcu just wasn't up to the weather. Perhaps Lucas designed the electrics. I fixed it by getting out of the lease.

[thermal runaway]

Difficult to understand issue's like that , Mercedes must do tropical climate testing ??!! Worries me when a company like Mercedes 'cannot' find faults !! Or is it 'don't want to' ??!!

[Conrad Hoffman]

Lucas, prince of darkness...

Reminds me of a BMW I once worked on. Often the engine would die when backing up. Never forward, only backing up. Turned out there was some electrical connection close to the chassis. There was something weird about backing up where the motor would shift ever so slightly on its mounts, shorting out the ignition to the chassis. Never happened going forward. The reaction forces on the engine should be the same both ways, so I never fully understood it, but some electrical tape provided a quick fix.

FORD- "found on road dead", "first on race day"
BSA- "bas---- stalled again"
Honda CVCC- "confounded very complicated carburetter"

[star882]

http://hackaday.com/2009/05/31/ghett...ronics-repair/
Lots of unusual "repairs" to electronics (check the comments).

[thermal runaway]

Originally posted by Conrad Hoffman

FORD- "found on road dead", "first on race day"
BSA- "bas---- stalled again"
Honda CVCC- "confounded very complicated carburetter"

Lotus ...........or , Lots Of Trouble Usually Serious !!!

[jackinnj]

FIAT -- "Fix it again Tony" -- and to think that Chrysler escaped Daimler only to be forced into the hands of Fiat.

My Dodge Magnum wagon, in addition to the hemi, has a Daimler inspired transmission and drive system, and all sorts of Bosch stuff in the innards. In 40k+ miles of driving the only thing which went bad was a connector which needed plugging back in. You'll see me going back and forth on I-80 all summer.