What was your easiest repair ever?

[TerraHertz]

To be more precise, what was your highest ratio of repair ease to value of equipment?

This was mine, a few days ago.
I was given a very cute, modern, small LCD projector, a DELL M900HD. It had been thrown out by a large institution due to being 'faulty'. It powers up, then after a few moments says "fan fail" then "over-temp, shutting down". Which it does.

On opening it up, this is what I found. There are several fans. They are not even screwed in, just slid into slots, with foam tape to prevent vibration noise. With the cover off they can be simply lifted out.
The two largest fans (still tiny) have rotor shafts that are only held in the sleeve bearings by quite weak plastic clips on the shaft end-ring. Mostly they are held in place by the field magnets.
Someone had bumped the projector sharply enough to dislodge one of the fan rotors. It had slid out of the sleeve bearing and wedged.

I just popped it back in, and screwed the case lid back on. Four screws. That was it. This is a really nice projector, very small, with lots of inputs, and even WiFi video input. Also the lamp is LEDs, so no short-lifetime HID lamp to fail.
In the pic showing it running I have the brightness turned down to the very lowest setting.

[nidlaX]

For me, it's a toss-up between my Telulex SG100/A (output SMD fuse), my HP 6543A (mis-aligned LCD), and my DE-5000 (input protection diode).

[DTJ]

Not so much electronic but it's used in my electronics workshop......

A large reasonable quality air compressor was thrown out for verge rubbish collection. I tested it and it didn't work. Pushing the overload button on the electric motor fixed it.

[Muttley Snickers]

This Dyson vacuum cleaner pictured below, I was driving home not long ago and happened to see a Dyson box out on the nature strip so I stopped to check it out, I noticed sticky tape over the power switch and in the box with the cleaner was all of the accessories. I had to take it.

I don’t normally scrounge this type of stuff but at the time we were looking to upgrade our existing thing that sucked, I happened to have a latching switch that fitted and gave the unit a good clean, it’s been great ever since.

[bitseeker]

Does a car count as equipment? Plenty of electronics. Well, I once had a Honda Accord and its Check Engine light came on. Pulled out the service manuals and based on the LED blink pattern on the ECU, the flow chart indicated a reboot to the ECU. Did that. Fixed. Problem never recurred.

Laptop that wouldn't boot anymore. Removed dead battery. Booted and ran just fine thereafter.

Let's see, what else. A dead 27" computer monitor. Classic fix with a $0.29 capacitor.

[iampoor]

I bought a bunch of audio gear "as-is" (owner didnt remember if it worked or not, and couldnt be bothered to test it). I made well over 500$ on a rack mounted spring reverb that had 1 open capacitor. That was a good day. 

The only piece of gear I couldnt fix was an Eventide 910 digital harmonizer. VERY cool piece of gear, unfortunately, almost impossible to economically fix.

https://valhalladsp.com/2010/05/07/early-pitch-shifting-the-eventide-h910-harmonizer/

 

[CaptainObvious]

Mine was probably when I was working at my old IT job.. they couldn't find out why this motherboard wasn't booting (was "recycled" by the customer... with first gen i7 and 12gb ram) lol I asked if I could buy everything for $50 instead of our company recycling the parts from it.. figured the ram was worth it if nothing else.

The fix? Installing a video card. They were trying to use the on-board VGA adapter, but the first gen i7 (960, to be exact) doesn't have an embedded GPU, lol... Still using it to this day as a file server for home use! (And I've long since left that company)

[george.b]

I work at a laboratory in the University, where someone once plugged a 110V printer into a 220V socket - not that unusual in a country where you have two voltage standards, one is twice the other and the sockets are the same. 
Since it was a color laser printer with brand new toners, I decided to try and fix it - only thing that had blown up, other than the fuse, was a MOSFET, which I replaced with another one, scrounged up from scrap. Good as new!

[bitseeker]

two voltage standards, one is twice the other and the sockets are the same. 

That's brilliant! There are so many things we learn about on the EEVblog forum.

[iampoor]

I work at a laboratory in the University, where someone once plugged a 110V printer into a 220V socket - not that unusual in a country where you have two voltage standards, one is twice the other and the sockets are the same. 

How do you tell the difference? 

[george.b]

Ah, let me clarify: it's not like both standards are there (officially) side by side at one given place, it varies according to location. For example, where I live we have 220V line voltage. One of the states neighboring mine has 110 (actually, 127, but we commonly call it 110), but someone living there could have their house wired with 2-phase 127V to get both 127 and 220V in the same household. Then you have to remember or mark which sockets are 220, so you don't blow stuff up, since we don't have different socket types for different voltages
Getting both voltages where I live isn't that simple, as we'd get 380V line-to-line voltage. Because of that, it's not uncommon for people to have transformers at home, and when a relative comes to visit, the question "is it 110 or 220?" usually comes up well, not as often nowadays, when most things you'd bring with you when visiting a relative have switching power supplies that can work with both, but still - power tools from one state, for example, could be useless in the next state if you don't have a transformer for it.

Edit: I found this nice little map that actually shows the different voltage areas within Brazil. You can see my state as an island of 220V surrounded by 110V

[BMack]

Master power switch turned off, get them several times a year. Bad power switches, messed up menu settings, batteries in remote, updating firmware, bad belt, bad caps...love the easy stuff, wish I got more of it! ...every customer seems to know that their unit is easy to fix anyway.

[Kilrah]

Hmm...
In the low end I'd say a simple halogen lamp that I saved from the dump collection point as a kid, and got to work again by just cleaning the slightly corroded lamp holder. Little $ value, but it was my bedside table lamp for several years, and I was surprised to find it still in use when I recently visited my parents after they made changes in their house, that's about 20 years later.

More recently a laptop whose owner got frustrated about the slowness and punched, destroying the HDD. He bought a new laptop obviously not to repeat the slow experience, I kept the old one and put it back in service putting an old (IDE) HDD that had just been collecting dust until then. Obviously not a crazy thing but it works perfectly fine, and is good to keep around thanks to hardware serial/parallel/IR ports etc as well as all modern interfaces.

Many more as a kid, I don't remember the details of what/how, but many times it was just a bad contact solved by shaking or cleaning things a bit, sometimes a cracked solder joint, broken rubber belt etc. Before my first job I barely ever bought anything and just equipped myself just by doing usually minor repairs on things people were throwing away.
Best way to learn things too since you're much less concerned about potentially breaking expensive stuff...

[CJay]

This Dyson vacuum cleaner pictured below, I was driving home not long ago and happened to see a Dyson box out on the nature strip so I stopped to check it out, I noticed sticky tape over the power switch and in the box with the cleaner was all of the accessories. I had to take it.

I don’t normally scrounge this type of stuff but at the time we were looking to upgrade our existing thing that sucked

Vacuum cleaners are meant to suck.

[CJay]

Does a car count as equipment? Plenty of electronics. Well, I once had a Honda Accord and its Check Engine light came on. Pulled out the service manuals and based on the LED blink pattern on the ECU, the flow chart indicated a reboot to the ECU. Did that. Fixed. Problem never recurred.

Laptop that wouldn't boot anymore. Removed dead battery. Booted and ran just fine thereafter.

Let's see, what else. A dead 27" computer monitor. Classic fix with a $0.29 capacitor.

Mine was a car too, £1900 book price GM people carrier with manual gearbox, the owner had been told by an 'expert' that the clutch had gone and would cost around £1100 to replace so he sold it to me for 'scrap' for £250.

The fix, 10 minutes with a pair of spanners, a wire brush and a dab of grease.

The pedal had rusted and siezed around the pivot bolt.

Ten years later and she still works .

[tautech]

Tek TDS210, display not working and given to me by an EE that couldn't/wouldn't even take the time to have a look at it. 
All the visual indications were there that is was booting, buttons illuminated etc.
No display backlight was confirmed with the usual bright torch to the display trick.
PSU checked OK and a scope probe held close to the discrete primary side oscillator of the backlight HV supply confirmed it was not oscillating. 30c resin dipped 0.47 uF gumdrop cap fixed it. Replaced cap measured pF's. 

Tidied her up, supplied a pair of new probes, put all the manuals on CD and sold it a few weeks later for good coin. 

[VK5RC]

An older HP psu,  sold as does not power up,  flicked the switch to 230v and she worked,  suspect the switch was a bit intermittent but still works on 115v now as well.

[Jwalling]

A TDS784C on eBay for $300 or so that "wouldn't power up." Fault: The soft power on button had gone high resistance. a dab of conductive paint fixed it. 

Jay

[Rerouter]

Was given a pallet (300 units?) of overload proof industrial constant current /voltage power supplies, under the assumption they where all faulty because the first 3 did not work. So had been sitting in a corner for a year or so.

Pulled the first one out of the packet, and indeed did not power up, looked in the packet again, and sitting in a small zip lock bag the fuse , was a great pay bump for an apprentice.

[Kjelt]

A Delta PSU 300VDC-5Amps, replaced one opamp and done.

[TiN]

HP 3245A. Wiggle some cables, and it was back online like new. I was washing front panel and taking photos much longer than actually getting unit to work..

[nctnico]

To be more precise, what was your highest ratio of repair ease to value of equipment?

I recall a keyboard with some burned fusing resistors and a TFT monitor with the same problem which where easy to fix. Or a PC which only needed a new coin cell battery.
My best one is problably this one: Two decades ago I got a defective HP6002A PSU (200W 50V/10A) and the owner said it had overheated and shorted a battery. He wanted to get rid of it because he was sure it was way beyond repair. However all I needed to do was bridging/repairing some burned out PCB traces and resolder some wiring which HP had goofed up. That PSU still works today!

[w2aew]

A Kenwood TS-940S ham radio HF transceiver refused to transmit on single sideband.  Removed, cleaned, tightened and re-installed the audio cable from the microphone to the main PCB - solved.

[Kleinstein]

At university we had an rather old Hitachi electron microscope running from an 230 to 110 V transformer. One of the circuit berakers got bad due to an terminal screw that was loose and got hot and thus tripped early. Luckily they had a second output with the same size fuse, but much lower load. So just swapping the two wires and add/change a label did the trick.

Another one was a controller for an vacuum pump, kind of a 10 V 70 A power supply, that had just a micro crack in a circuit board. A little hard to find, as one could not see it. But fixing it was easy (no protective coating) by just short piece of wire.

A slighly more tricky one was a HP computer (some 7000 series UNIX workstation) with burned network interface (likely due to a broken external AUI to ethernet converter). It was just replacing a fuse. We had a similar problem before, while the unit was still under warranty: a technician came from HP and changes the mother board. Could have been the same problem before.

[TheSteve]

HP 8714C 0.3 - 3000 MHz network analyzer - flipped the 110/240 selector switch back and forth a few times and it came to life. So the fix was 10 seconds but I still spent 5+ hours cleaning it and then recapping the power supply as part of preventative maintenance.

[GreyWoolfe]

I once received a service call for a receipt printer without power.  I spoke with the person on whose desk it sat and asked her to double check the power cord.  2 minutes later she got on the phone and said she did and still no power.  1/2 hour drive, looked under her desk  and pointed out the plug sitting on the floor.  I plugged it in and told her to have a nice day.  The equipment was under contract so she couldn't be billed for stupidity.

[Howardlong]

Tek 2467B, last weekend. "Test 02 Error 04" on startup. It's been like that for a few months, and I'd just got around to looking at it, on the assumption it was going to take a while to fix. When I've had similar looking errors, I've had to either do a re-cal and/or replace the battery backed up RAM or battery, so I took the case off.

Looked up the error, turned out to be a stuck front panel button, fixed in a couple of seconds.

What did I learn? RTFM of course.

[tautech]

I was given Oki 5200 color laser that wouldn't print properly. IIRC the page count was less than 2K.
Turned out to be a sheet of paper wrapped around the fuser drum. 

Several K pages later it's still going strong. 

[rrinker]

 I got a big discount off a used 1987 RX-7 because the display board in the center of the dash (clock, warning lights) was dead. Electrical problems seem to always scare and stump otherwise great mechanics. They don't bother me (I wouldn't have pursued an EE degree if they did). So I drove the car home, and poked around to see how to get this panel out. I popped it out, there's just one electrical connector. When I pulled the cable off I saw the problem immediately - the part of the connector soldered to the panel's board had cold joints on half the pins. I took it in the house, fired up my soldering iron, redid the bad joints, plugged it back in - all worked, and continued to work for the next 4 years I had the car.

   

[mzacharias]

I have worked mainly in audio repair so I've had many. Dirty laser lenses on CD players. Scratchy potentiometers only needing cleaning. Yellow glue turned brown and conductive / corrosive. Tape monitor buttons pressed IN on integrated amps or receivers. Bad solder on FL tube filaments. Bad solder connections generally. Series - connected speaker switches pressed IN for nonexistent "B" speakers. Missing pre/main jumpers on receivers. Screws needing tightening. The list could go on and on.

[JohnWard]

Plasma TV - one of the huge ones which required several people to move it.  Customer said it had no sound - everything else worked.
Not exactly keen to dismantle or even move the thing, so first shoved some audio into one of the many inputs - sound blared out at full volume.

The problem was that the customer only used it with the HDMI input, and that had a menu option to disable the sound so that an external sound system could be used instead.  A few presses of the remote control, and the 'fault' was fixed.

[bitseeker]

This thread is turning into a great "check this first" guide.

[lukier]

SRS SR850 lock in amplifier. It was thrown away because half of the CRT screen was black and unreadable. Someone even wrote on the case "GPIB ONLY IN PRINCIPLE". I had to bend some metalwork, but this I suspect was the damage caused by the workers chucking this boat anchor into the dumpster. The real problem (CRT image) was just soot and fine dust collecting on the acrylic in front of the CRT tube, as the high voltage in proximity likes to attract such dirt. Some cleaning and SR850 is good as new, well within spec (under 6 nV/sqrt(Hz) input noise).

Also few E3631A. One had faulty 30K ADC resistors (mentioned by free_electron somewhere here), another one just grease in the rotary encoder and the third one took the longest to debug - faulty SRAM causing the CPU to crash.

That's pretty much it from the dumpster. On eBay I once picked TTI TG1010A for 35 GBP. It needed a replacement battery (non critical, just waveform storage & settings) and had a cold solder joint on one of the SOT-23 transistors (AFAIR) used in row/column matrix switching for the keypad (the first column of buttons didn't work).

Surprising amount of eBay "for parts or non working" purchases turn out to be perfectly fine. I'm not TheSignalPath, I cannot afford to risk $500 on something broken (well, I cannot afford $500 on anything most of the time anyway), so these are rather really bottom of the range scores, $30-$50 most of the time with few exceptions in the $100-$150 range where I had some gut feeling (or judging from the photos) that the thing is OK or fixable.

[BMack]

Plasma TV - one of the huge ones which required several people to move it.  Customer said it had no sound - everything else worked.
Not exactly keen to dismantle or even move the thing, so first shoved some audio into one of the many inputs - sound blared out at full volume.

The problem was that the customer only used it with the HDMI input, and that had a menu option to disable the sound so that an external sound system could be used instead.  A few presses of the remote control, and the 'fault' was fixed.

I thought you were going to say the TV had external speakers, I've gotten that a few times. It's hard for a TV to have sound output when it's missing the speakers.

[matt6ft9]

A couple of days ago, I noticed one of my Airlink IP camera's was not showing up on the network and had an amber LED that would flicker about every second.  Normally, the LED would be off.  After a short investigation, the 5V, 2.5A wall pack had crapped out.  The walpack was replaced and the IP camera is happy now.
-always check the wallpack-

[VK5RC]

One of the saddest things is , as I read with interest all the "quick" solutions to problems,  I have had a good proportion of them but quite a lot took me WAY TOO long to find. FFS

[Gyro]

My easiest one was probably the Toshiba laptop that I bought from an office equipment auction (a proper auction, not ebay). It was a TFT display one, this was in the days when STN was common for the color ones. Anyway it was listed as display not working and I got it really cheap. I got it home removed the bezel and plugged in the display connector and it worked perfectly.

It was a proper connector not a flexiprint so there's no way it could have slipped out. I can only think that someone in the office had thought they'd try to bag themselves a free laptop from the bin but the company sent it off to auction instead! 

[HighVoltage]

Plenty of easy repairs.

Bought a scope "not working" ----> PSU cable was off

But most easy:
an expensive industrial WAP vacuum cleaner was given to me with the comment: This one "sucks" (pun intended) because it does not work and obviously did not suck any dirt.
Well, as unreal as it sounds, the bag was full!

 

[CJay]

One of the saddest things is , as I read with interest all the "quick" solutions to problems,  I have had a good proportion of them but quite a lot took me WAY TOO long to find. FFS

Definitely, I reckon we would all have been caught out by them on more than one occasion.

Go check out the BEC test thread and the video of Dave trying to repair a controller on a quadcopter for a prime example of a lesson I've learned the hard way too.

[bitseeker]

as unreal as it sounds, the bag was full!

Fantastic!

[bdix]

Tektronix 576 curve tracer. The Readouts were gone. A replacement had already been ordered. Appears someone had turned the readout intensity all the way down. Just turned it back up.

[SeanB]

Plenty of easy repairs.

Bought a scope "not working" ----> PSU cable was off

But most easy:
an expensive industrial WAP vacuum cleaner was given to me with the comment: This one "sucks" (pun intended) because it does not work and obviously did not suck any dirt.
Well, as unreal as it sounds, the bag was full!

Funny enough, a Hoover branded bagless cyclone cleaner, which was full of dust, and where the cyclone was packed solid with dust and carpet fur as well.  The flat pleated filter was a flat surface on the inlet side from dust. A few wash cycles and some digging out of the kilo of felting inside the housing, and a good drying and it now sucks quite well, though it is incredibly noisy, compared to the other canister vacuums I have.

Another was a Hoover upright, which was not sucking. Needed a new belt for the brush, which was slipping and thus not turning the brush, plus a little work with some PVC sheet to make a new cover for said belt, as this is also the suction inlet. Not going to pick up much with no brush rotation and with all the suction coming from a small spot at the back on the one side. Had to shorten the inlet hose slightly as the cleaners had bent it ( how, when it has a nice tray to hold it) and crushed the end.

[guido]

Fluke 335D voltage standard. On the back there are two fuses. One is low current and the other one high current. The low current fuse instantly went bang at power up. Took me only a moment to find that somebody swapped the fuses. Put the higher current fuse in the correct holder, put in a new lower amps fuse and it worked. 

[GreyWoolfe]

Tektronix 576 curve tracer. The Readouts were gone. A replacement had already been ordered. Appears someone had turned the readout intensity all the way down. Just turned it back up.

I actually did that to the monitors of a pair of cranky old ladies at a job I had many years ago.  Very funny watching them go crazy trying to figure out what was going on.

[CJay]

Funny enough, a Hoover branded bagless cyclone cleaner, which was full of dust, and where the cyclone was packed solid with dust and carpet fur as well.  The flat pleated filter was a flat surface on the inlet side from dust. A few wash cycles and some digging out of the kilo of felting inside the housing, and a good drying and it now sucks quite well, though it is incredibly noisy, compared to the other canister vacuums I have.

Possibly noisy because the motor may be damaged, when there's lower air pressure the motor will overspeed and may damage bearings if left for any length of time.

[TimFox]

I have done quite a few repairs on instruments from the days of real rotary switches, where the only work needed was to clean thoroughly the switch contacts with contact spray (I now use Gold-X).  This was true for a few vacuum-tube units as well as solid-state units.

[oldway]

I know I will make some jealous! 

I bought in a flea market a not working Marantz 2285B for parts for 35 euros.

Examining the receiver, everything seemed in order, no burnt components, no blown fuses, almost new.

I powered it progressively on with a variac and everything was ok.
It was working. 

The problem ?
All dial lamps were dead, giving the impression that he did not power on. 

[Wytnucls]

My newly acquired Fluke 867B had a strange behavior on the component test selection. It would sometime cycle through a couple of correct screens then go blank. Applying pressure to the meter face, seemed to recover functionality.
Opened it up, followed traces routing away from the front selector switch to stumble on a capacitor which didn't look right (between selector and PCB screw). There was hardly any solder on one side of it. Reflowed it with extra solder and Bob's your uncle, problem solved. 5 minute job. I wish it was always this simple.

[NivagSwerdna]

I once bought a new but faulty guitar amp...

I unscrewed the box, found the speaker leads were hanging, never connected.  Attached them, closed up the box and had a nice guitar amp.

 

[bitseeker]

All dial lamps were dead, giving the impression that he did not power on. 

Nice one. As always, "Know thy equipment." Or, failing that, "Read thy manual."

[vk6zgo]

Back in the '70s----little "El Cheapo" AM CB radio from K-Mart.

It put out the full "humungeous" 4 watts,but nobody could hear me.
Took it to work.looked at it with the CRO---It was making about 1% modulation.
Opening it up,I found that the 0.47uF coupling cap in the mic amp was actually 0.0047uF!
On replacing it with the correct value,all was well.

Interestingly,the schematic in the "Owner's Manual"* said 0.47uF,but the Parts List (BOM to the children) said 0.0047uF.

No guess which the assembler worked from!

*Oh for the days when a $25 purchase had a Manual with a schematic!!

[bitseeker]

Reflowed it with extra solder and Bob's your uncle, problem solved. 5 minute job. I wish it was always this simple.

Yeah, tell me about it. Had some decade boxes with bad solder, too. If only everything was so easy.

[TerraHertz]

Today, a friend brought round a nice Xeon server PC he'd scored free. Junked due to 'no power up'.
Coin cell flat, replace, still no power up. (Some PCs, if the cell is dead the motherboard won't signal the PS to start.)
Checked power supply: P_ON# line does nothing, and +5V_Standby is 2V. Opened supply, after some quick checks (Fuse OK, HV DC OK, main transistors seem OK) noticed two small electros in the standby supply had domed-out tops. Replaced them (two 1000uF 16V) and now the PC works. He's happy, and so am I since that's a favor returned.

[SeanB]

Funny enough, a Hoover branded bagless cyclone cleaner, which was full of dust, and where the cyclone was packed solid with dust and carpet fur as well.  The flat pleated filter was a flat surface on the inlet side from dust. A few wash cycles and some digging out of the kilo of felting inside the housing, and a good drying and it now sucks quite well, though it is incredibly noisy, compared to the other canister vacuums I have.

Possibly noisy because the motor may be damaged, when there's lower air pressure the motor will overspeed and may damage bearings if left for any length of time.

They are all noisy, just because of the lower cost manufacture, so they do not put in any sound dampening foam or anything like an outlet filter. If it does die I can get the whole motor assembly cheap enough though, around $ 25, and fix it. Amazing how many assorted vacuum cleaners use the same 5 different motor assemblies inside, with most being covered by 2 only, a single and a double stage pump and motor. Same motor assembly in the $30 unit as in the $200 unit, just the one has a fancier case, more foam damping and 2 extra filters and a flashier external casing.

In any case the motors are all made now with CCA wire and with the design voltage being 200VAC, which means a shorter life on our standard 230VAC mains, though with the thin power cords that are used the motor will probably run at 200VAC in any case, with 30VAC drop along the cord in the steel strands.

Currently local mains is 234.2VAC, though it vcan be as high as 239VAC, and I lived in an area which still has the original transformers from 1910 in service, where the whole district had mains that ranged from 235VAC at lowest to 255VAC at highest, as the original standard in South Africa was 250VAC mains, later harmonised to 240VAC and finally to 230VAC. Made for great heating, but a really short lamp life.

[Koray]

Great thread! I hunt for broken stuff on ebay all the time!

My easiest repair was a corroded battery cover on a brand-new condition Metz MZ54 professional camera flash unit. Just a puff of contact cleaner and it came to life.

Another find led to a goldmine for me actually. Fujifilm F30-F31fd cameras had an inherent problem with the battery door not latching in properly, leading to door sensing switch staying open. Finding out the problem I scored many of them, repaired and resold for easy money for a year or so.  Similarly, I  managed to fix many Canon EOS cameras with blown SMD fuses, another goldmine.

Again, I once scored a faulty Denon RCD-M39DAB unit, having issues with some buttons on the front panel. While I was expecting to dig in microprocessors and all, it turned out to be a cracked single sided PCB. Apparently someone knocked on the volume knob and cracked it! A few jumper files, and it was all set. 

Oh and there was this Sony BTX500, which I repaired by the help of the crowd here, where the thing came to life when I was poking with a multimeter. A jumper cable was all that was needed.

These are only a few that I can think of...



Koray

[Samogon]

Keithley voltage source 230,
Got for $112 as not working, on the back there is input voltage markings ticked 220V but 110V was painted over so i assumed that this was used as 110 but then tranformer fried.
Opened case flipped 110/220 switch and I have fully functional unit.
Of course cleaning and some case fixes with epoxy.

[pelule]

Got an HP 419A as "for parts only", paid $21 including shipment. Defekt: the power cable was broken.
PeLuLe

[Skimask]

Worked at a fixit shop while in the USAF.
Guy moves from England back to the U.S.  Walks in with an audio amplifier.  Says it doesn't work and he's been to 3 shops already with no luck.  Says he'll buy the whole shop lunch for a week if we can fix it.  Sets the unit down on the desk with the rear facing me. Without miswing a beat, I reached over, flipped the 120/220 switch, and asked him if he had a van or a bus to haul us all to lunch.

[smugtronix]

Not mine, but for a friend:
1974 Ampeg V4 guitar amp that he picked up for $200, the only piece of information I had was "It doesn't turn on". Surprise surprise, it was a blown fuse. I still rebuilt a majority of the power supply (These amps run insanely hot, and a bunch of the carbon film resistors in the bias supply had drifted way out of spec, so I replaced those to hopefully cut down on the noise). Easily one of the loudest amps I've ever heard, and thankfully none of the tubes have gone microphonic, it costs a small fortune to fully retube one. 

[sonicyang]

Got one HP54600A with popped cap in CRT assembly.
The cap is easily accessible, I don't even need to take the board out of the frame.

Replaced, and become working for another 3 years till now.

[PaulAm]

I bought a Fluke 332b voltage standard for cheap sold as non-working - no output voltage.

The voltage-trip control which disables the output when the voltage exceeds the setpoint on the front panel was set at 0V.  Turned the knob to the right and I had a completely functional 332b.

I recently picked up a Tektronix 1502 TDR marked as totally fried.  I opened it up, reattached two hanging cables and it worked fine off of a power supply.  That one still needs a battery pack.  That was easy, but not quite the same as the 332b.

[calmtron]

HP 5334A Universal Counter, sold with the description "Powers up but does not respond to input". Turned it around and toggled the timebase selector switch on the backside from external to internal - fixed!

[Smith]

To name just a few:

Expensive Marants cd player for next to nothing because the laser was bad. Just blew the dust off the laser, and after >10 years it still works as my daily cd player.

Onkyo surround amp for 10 bucks (with HDMI, usb support etc) for 12 bucks. Jumpwired the thermal fuse of the transformer, all is fine.

Keithley 199 wich was bad (and free). Cal was gone because of empty eeprom. Just calibrated it, still works fine.

[Kjelt]

Onkyo surround amp for 10 bucks (with HDMI, usb support etc) for 12 bucks. Jumpwired the thermal fuse of the transformer, all is fine.

Rather place a new thermal fuse against or better in the transformer, you never know .

[bitseeker]

Turned the knob to the right and I had a completely functional 332b.

That's excellent!

[retrolefty]

Easiest repair I read about was in the air force. Repair write up on a specific pilot complaint stated no problem found, suspect intermittent short between the headsets. 

[RobertHolcombe]

Not a repair, but...

My family bought a no name brand LCD TV in the mid 2000s and it worked for a while but eventually the sound stopped working. We took it back to the store to exchange it but had to first have them test it to determine if it was in fact faulty. They plugged the power in but the TV didn't turn on from the power button or remote    We and the staff were both puzzled... turned out there was a power rocker switch on the bottom edge of the display which was conveniently placed where a person would hold the unit while picking it up.

[Chris Mr]

16 x USB MIDI music keyboards from a local school

Every one had the USB socket broken on the PCB - you couldn't tell from the outside

4 screws out, change the socket, 4 screws in

They were delighted 

[charlespax]

My 12" MacBook was having some sort of RAM problem. After running for a bit the system would halt and display an error message. I removed the RAM module and got the same issue with using only the RAM soldered to the motherboard. I desoldered and lifted the power pins on the onboard RAM chips and got the system running on just the RAM module. Not a complete fix, but it got things working again.

[tautech]

Charles reminded me of a Toshiba Satellite 200 laptop with a Bios driven integral fingerprint reader as the default system login and it wouldn't/couldn't boot. 
A bit of Google'ing discovered that early bios versions would without reason enable the fingerprint reader and effectively render the laptop useless. 
Online comments were of the order: it will lock you out but who knows when.
Further Google studies found the "secret" reset contacts under the ram modules and with those momentarily bridged with the power button simultaneously pressed and tongue held at correct angle the Bios could be reset. 
Upgrade Bios to later version....fixed.

Supposedly several "experts" had attempted to "crack" this laptop and it was given up as lost  and I still use it occasionally today.

[BMack]

One of my shop techs bought a "Non-working" bluetooth speaker from a pawn shop for $1. He decided it was worth a shot trying to fix it but he's been busy lately so it's just been sitting on his bench for the past month. I ran out of stuff to do today, just waiting on parts, so I decided to take a look at it. I push the power button, nothing. I hold the power button down for 3 seconds, it turns on. I pair it to my phone and bring it to him playing music. 

[iXod]

50 in Samsung DLP 1080p TV. Rescued it from scrap heap. It would turn off pretty regularly after warming up for maybe a half hour. I did a net search on the symptom, turned out that the door on the back that gives access to the lamp has a microswitch that goes high-R. I cut and soldered together the switch's wires. A friend gave me a Sam remote. It's been working well ever since (3 years). None of those flat-panel failures (lines, etc.). Great picture.

[EduardoLM]

Perhaps not so easy, but with great value for me!

Some time ago a friend gave me one of those Hantek USB scopes (DSO-2150), that used to work for some weeks, then stopped working. He got pissed of it, after he tried to fix it by replacing one of the TSSOP A/D chips, but he ruined one of the part tiny legs.

I have managed to use a Dremel to excavate the tiny TSSOP epoxi and bridge the missing pin back into place, but that didn't fix the main fault. I noticed that by flexing and pressing the board, the scope would work, but it stopped working as soon as the pressure was removed.

So I got my magnifying lens and started checking each IC pin, and found the main FPGA with missing solder on one pin. Ressoldered it, and the thing got back to business, rock solid, never failed again!

Later I sold this unit and used the money to buy my first real scope, a Tektronix TDS-1001C, which is not great, but much, much better than that Hantek USB thingy.

Eduardo

[Assafl]

Interestingly,the schematic in the "Owner's Manual"* said 0.47uF,but the Parts List (BOM to the children) said 0.0047uF.

*Oh for the days when a $25 purchase had a Manual with a schematic!!

I always wondered what happened with the schematics for household electronics. An older shop owner enlightened me with a reasonable explanation - that in the old days, tube equipment always had schematics since tubes would burn out and need replacement - even by users (in those days rummaging in high voltage equipment was considered ok for lay users - until politicians learned that policing electronics is power); as the evolution to solid state was happening, manufacturers would still give away schematics - since it was what they did.

Replacing a transistor (let alone and IC or worse - SMD) is far more trouble to plugging in a tube - so over time, the schematics got relegated to service manuals for professional use only (with lots of legal waivers, warnings and cautions etc.), and today, having realized that replacing boards is far more lucrative than fixing them - made the schematics disappear forever for many a household product - how unfortunate.

OT: I have been playing with electronics since 1981 or so. In those days noisy pots were the easiest fix - contact cleaner would restore any Marantz (including my parent's) to former glory.

[HighVoltage]

When I grew up in Germany in the 70s and took my first TV sets apart, they all had full schematics in a special side bag inside the TV. And these schematics even had scope pictures in them.
One can only imagine, how much work that was to produce them by hand.

Those days started to fade away already in the mid 80s in Germany.

[Assafl]

When I grew up in Germany in the 70s and took my first TV sets apart, they all had full schematics in a special side bad inside the TV.
And these schematics even had scope pictures in them.
One can only imagine, how much work that was to produce them by hand.

Those days started to fade away already in the mid 80s in Germany.

You know this trend was limited to household stuff. I got a SMEG professional (restaurant) dishwasher and was surprised that it had full diagrams (blocks diagram wiring - not schematics) under the footboard. Mitsubishi air-conditioner still has one as well (and service manuals online).

But unfortunately, home stuff does not. E.g. trying to get a Gaggenau diagram from BSH requires a real bribe. Miele is even worse. Unfortunate since neither has service of any quality (or even mildly knowledgeable) outside Germany and some big cities like New York. In Israel BSH and Miele are awful.

[CJay]

When I grew up in Germany in the 70s and took my first TV sets apart, they all had full schematics in a special side bag inside the TV. And these schematics even had scope pictures in them.
One can only imagine, how much work that was to produce them by hand.

Those days started to fade away already in the mid 80s in Germany.

Oh I remember those, Grundig televisions were pretty much the only German sets I ever worked on but those schematics were excellent.

We used to get 'first issue' service manuals for Philips equipment for free but you had to be a dealer to order them.

All those 4822 numbers...

[HighVoltage]

Yes, you are right!
Grundig had by far the best schematics around and they were printed in color!
And for the big TV sets, they filled a table in size.
I should have kept one, just for fun.

[CJay]

Yes, you are right!
Grundig had by far the best schematics around and they were printed in color!
And for the big TV sets, they filled a table in size.
I should have kept one, just for fun.

I've probably got one somewhere, lurking in an old box of Television magazines, I know I have a few of the alignment trimmers they used to include inside the sets and I still use them to this day.

[alterbaron]

Our lab at work inherited a really nice 1KW switching lab power supply that wouldn't power on.

Turns out the front power switch had failed open. One new power switch later, and the thing works a treat!
Better yet, the power switch was wired up using quick connect plugs. No soldering required!

[KeepItSimpleStupid]

Car clock:  Jumped car.  Clocked died.  tried to find replacement clock $400.00 USD. Unhooked car battery.  Shorted battery terminals toward car for a few minutes.  Fixed.  Lots of things fixed that way.

Recent ebay Keithley 485 with IEEE cheap <$100.00 USD.  Cut power cord.  Crack in the case.  Put it into another case temporarily and set he voltage switch right.  No issues.  I ordered parts to replace the cord and the feet.  Glued the crack.

Two other 485's broken.  Bad FET. $6.00.  I can't find the FETS I used to fix the K485, but another seemed to suffer the same fate.  Troubleshooting takes about 10 minutes.  So, two now need calibration.

I would not call the next repairs easy, but they were straightforward.  A 13 kV  1.5A power supply for an e-beam kept blowing the same transistor about every 6 months.  My predcessor just replaced the transistor.
I replaced the transistor,  a 1 Meg 200 W bleeder and some 625K resistors in the voltage divider and got out my bottle of Locktite 222 and tightened every electrical connection possible.  Did that on a 100 kV 0.1 A X-ray supply too after replacing a few components.  We had bought a 3-source e-beam evaporator at auction for like $45,000 USD.  Instead of removing the connectors, they cut all of the wires a few inches from a terminal strip.  The connectors were hidden - I'll give it that.  the HV wires were also cut.  You just had to remove 3 screws.  Methodically, it went back together SLOWLY.  Locktite to the rescue again and tthe HV regulator tube popped out of the socket.

RS232 driver kept blowing on a Databox (An after-market goniometer automation gadget).  Isolated the RS232 lines.

The 10 A rectifier where a 50 A should be,  That was super easy.  Yell at the manufacturer (we had a good relationship) and they fixed it for free (new transformer and new rectifier with a new design).

The HVAC guy at our place decided that the air to water heat pump in the ceiling was bad, so he ordered another and had it installed in the ceiling.  He could not get it to work.  I gave him about 10 minutes of my time and said replace the t-stat wire after he did some measurements under my direction.  During a re-model the t-stat wire got caught on a metal stud.

A Keithley 4 quadrant source.  I'd have to find the number. Wrote a  program to exercise the OUTPUT ON relay overnight.  Fixed  the next morning.

An impatient neighbor called me that her cable box wasn't working.  The all-in-one remote was toggling the TV on and the cable box off etc.  So much for dedicated ON/OFF commands.  Checked IR LED with cell camera.  Got them in sync and replaced the batteries in the remote.  I suspect that the sensitivities of the cable box and the TV were different.

Same neighbor called me and the box was showing some sort of crypic error.  She doens't know about capacitive buttons and the box was unresponsive to the power button.   Unplugged it to re-boot.  In the meantime she's trying to call the cable company. Basically let them guide me.

[CJay]

A Keithley 4 quadrant source.  I'd have to find the number. Wrote a  program to exercise the OUTPUT ON relay overnight.  Fixed  the next morning.

Was told a story by an ex colleague of mine, he worked at ICL in Cheshire back in the day when we Brits made computers.

One of his colleagues developed a test rig for the pneumatic valves used in tape units for the (I *think*) ICL 2900 mainframes, said test rig would exercise the valves and help eliminate failures.

Sadly for him, the rig didn't take into account the lifespan of the valves and after a weekend long run he came into the workshop to find several thousand pounds sterling of wrecked pneumatic valves.

[KeepItSimpleStupid]

I hate it when you buy brand new valves (24 VAC coils) and you have to take them all apart and clean them to get rid of the dust or they hum.  Today, I re-built 3 natural gas manual valves.  Not as fun as much fun as rebuilding  a carb.

Or brand new wafer probe needles can't be used at high T unless you boil them in baking soda and electroless gold plate them.

Then i really hate when the manufacturer changes from brazing to 60/40 solder and the needles fall off.  Fortunately, they were able to use Sn96 for us.

[LazyJack]

This baby was on eBay for a long time. Advertised as being in the notorious "Powers up, not tested" sate. The picture there showed indeed nonsensical display, with conflicting lights and missing segments. But, as this was the military version, with GPIB and oven oscillator it was bugging me to get it. So finally took a chance, as it was cheap.
First try, it did exactly what was shown on the picture, garbled display, no reaction to the buttons. I checked voltages, the -5.2V supply was 0.5 instead. Strange. Pull the GPIB board first. Nothing. Pull the Channel C prescaler board, it works! Check the obvious for shorted caps etc. on the prescaler. Nothing. Put it back, it still works! Very strange.
Put everything together, still works and has been ticking on my desk now for a couple of hours.

I have no idea what was causing this, could have either been some short, like a solder blob or something touching something else, which fixed the issue. Only thing to fix is the small fuse inside the Channel C BNC, it's blown, needs replacing, but bypassing it showed that Channel C works.

Extra bonus: all the buttons work fine, even though this model is known for the buttons failing.
So this repair was quite easy, take it apart and put it back together.

[Jeff_Birt]

I filled out a 20 or so page PO request, had a background check, drove 5.5 hours one way, went through security at a nuclear power plant, and flipped a switch on a plasma cutting power supply.

[GreyWoolfe]

I filled out a 20 or so page PO request, had a background check, drove 5.5 hours one way, went through security at a nuclear power plant, and flipped a switch on a plasma cutting power supply.

 

[bitseeker]

Put it back, it still works! Very strange.
Put everything together, still works and has been ticking on my desk now for a couple of hours.

Very strange, indeed, but what a score. It is somewhat rare to get one with all good buttons.

[whitevamp]

back ohh probably 20yrs ago, i was driving down a freeway and noticed a car with the hood up and i decided to stop and see if they needed any help and they said that they called a cab to come get them and that he was fed up with the car always breaking down and i offered to look at it, and he said ok and ill tell you what here is the title for it its all yours if you want it, ( he was going to go to a car dealer and get rid of it.) and i said ok so about this time the cab shows up and off he goes and i look at it and i see what it is so i run to the parts house and get a new cap and rotor for it go back and put it in and i had friend with me and off we go 2 days later i sold it for a very nice profit. 

[CatalinaWOW]

Adding to a theme mentioned several times above, I was on call to maintain a test station worth over a million dollars (in the dollars of four decades ago).  Arrived in response to a trouble call and it took less than a minute to observe that the equipment function far better with the power cable plugged in.  Someone had kicked it out without noticing.

[BurningTantalum]

I once had to make a service visit to look at a non-functioning machine guard system. I flew business from the UK to Hong Kong, then had a three day wait for a visa for China. I then sat all day in Kai Tak due to a weather delay, and got very drunk with my colleague who came along in case the issue was mechanical. We flew down to somewhere near Hainan Island and went to the factory the next day. While my colleague was organising a jar of tea leaves I opened the panel, saw that one of the relays was a different colour and was in fact an AC type. I pulled it out and swapped it for the correct DC type from an unused circuit.
All was then well. We had to wait a week for a return flight, then two days in 5 star Hong Kong and a business return to the UK.
My colleague always told the story as my fix "took 5 minutes" but in fact it was nearer to 20 seconds. I don't know the cost per second to the customer, but it must have been considerable.
BT

[BurningTantalum]

Oh, and we had such a row whilst drunk at Kai Tak that he was still trying to throw punches at me as I dragged him to the gate. Neither of us could stand up properly, but CAAC was quite forgiving in those days. They gave us more drinks once airborne !
BT

[SeanB]

A Keithley 4 quadrant source.  I'd have to find the number. Wrote a  program to exercise the OUTPUT ON relay overnight.  Fixed  the next morning.

Was told a story by an ex colleague of mine, he worked at ICL in Cheshire back in the day when we Brits made computers.

One of his colleagues developed a test rig for the pneumatic valves used in tape units for the (I *think*) ICL 2900 mainframes, said test rig would exercise the valves and help eliminate failures.

Sadly for him, the rig didn't take into account the lifespan of the valves and after a weekend long run he came into the workshop to find several thousand pounds sterling of wrecked pneumatic valves.

Reminds me of fixing ATE relay boards. Bad board, so swap with a spare ( lots of fixed boards) then take the board, look which relay was faulty ( mostly high contact resistance on the mercury wetted relays) and remove the relay, tap it on the bench to get the mercury drops back to the one end, and tap again to move them back to the contact area, then test it again. most of the time it would pass resistance testing and be soldered back in the board. Nice that the ATE test program ( which took around 3 hours to run) would tell you exactly which contact and which relay was faulty, along with being able to diagnose cable faults in the test looms as well, using the special loopback test configuration block and the loopback testing lead set.

[setq]

Not one thing specifically but literally everything I buy as dead as untested so far just needs cleaning and works properly!

[Messtechniker]

PC dead as a Dodo. Should have gone to waste.
As so often: one bulging electrolytic in the PSU trying to blow its head.
Replaced with the same type salvaged from a very old motherboard.
Works. However, would not use it for anything critical.
C had 17 uF instead of 1000 uF.

[R005T3r]

My easiest repair ever done was:
Unplug the pc from all the calbes
slide off
connect the Hard drive sata cable
slide on
connect

50 bucks earned in 1 minute

[HackedFridgeMagnet]

Went around to fix this ladys oven, she was keen to do some cooking so she said she would kiss me if I could fix it. 
This was in front of her mother and father too, who were a bit embarrassed about this offer, like myself.

Anyway I tried my damnedest to fix it but couldn't figure it out. So I said I would take it away and try to fix it at home. 

When I got it home I somehow got it working, I cant even remember how, possibly a bad connection on what should have been the neutral, anyway it didn't need parts.
So I rang her up, by this time it was about 3 hours later and she said she had already bought another oven!

So I missed the kiss but got the old oven.
It's a good oven, 2 in 1, Still going strong.

[retrolefty]

In the U.S. Air force it was known that many airmen would write out their maintenance report:
"No problem found, suspect intermittent SBH, short between the headsets" 

[SeanB]

I used to work on avionics, and got a bomb aiming computer in with the following terse description of the issue " First bomb fell on target".

Phoned the pilot in question, and asked for a little more info. Thanked him, then checked where the plane was, and. as it was in for a scheduled maintenance cycle, phoned the shop and asked the relevant person to check a certain part. Then tested the unit, and sent it back out with absolutely nothing wrong with it. Didn't get feedback ( regular thing) but guessed that another box went off to another service unit on the scheduled mail delivery.

[JacquesBBB]

I got once a ISO-TECH IPS2303 (same as Instek GPS2303) Power supply in the dumpster of a  physics lab.
quite new  2 x 30V 3A lab PSU.

I was ready to make a  serious work on it, and  start to open it, when I realised that the fuse was blown. I could have even avoided to open it as the fuse is on the plug and accessible from outside. I replaced the fuse and its working fine since.

What strikes me is that this comes from a physics lab where they are supposed to know quite a lot on electronics.

[Berni]

I bought a HP 8082A Pulse generator (Up to 250MHz and 1ns rise time) off ebay where the seller claimed it does not power on. But it was in nice condition and got it for like 50 bucks.

When it comes in the mail i see the fuse is missing so i put one in. Then i tried powering it on and there was no power light however i could hear a transformer hum in it. So i check the output BNC and we got a signal, everything worked. So then i opened it up and to figure out why the power LED was not turning on i used a multimeter to check if there is voltage coming to it. But once i touched a spring loaded contact behind it it lit up so it just had a bad connection and i found out that its a incandescent light bulb not a LED.(Yeah its a very old instrument)

So yeah the fix was basically putting a fuse in it

[Wirehead]

Yamaha RX-V457 / Yamaha RX-V650.. 20 cent X2-Rated cap in the stand-by power supply section. Took me more time to screw the thing open, than to solder the new one in.

[CJay]

Adding to a theme mentioned several times above, I was on call to maintain a test station worth over a million dollars (in the dollars of four decades ago).  Arrived in response to a trouble call and it took less than a minute to observe that the equipment function far better with the power cable plugged in.  Someone had kicked it out without noticing.

Similar albeit not quite as expensive.

A manufacturer of 'specialist ceramics' (read submarine sonar transducers, they were very cagey about what they made but the pictures of the British nuclear sub fleet on the walls in reception combined with the name of the company and knowing which contract the call was logged under made it pretty damn obvious) called in a fault with their production server, they'd done a site power down to test backup supplies, generators etc. and the server had hung up on POST with an error relating to SCSI termination, the result being that they couldn't restart the production lines.

The fix?

Unplug the redundant SCSI cable inside the server, they had added an Ultra 160 card and stopped using the motherboard SCSI controller, at some point the active terminator on the motherboard SCSI cable had failed.

[TheBay]

I often buy faulty items on eBay and fix them, I won a Lenovo laptop which was just over a year old, said faulty does not work.

Turned up and it indeed did not work, went on Lenovo website to find out the exact specs etc, still had another 2 year warranty on it, posted it to Lenovo and it came back fixed.
Didn't even need to attempt a repair.

[HighVoltage]

I often buy faulty items on eBay and fix them, I won a Lenovo laptop which was just over a year old, said faulty does not work.

Turned up and it indeed did not work, went on Lenovo website to find out the exact specs etc, still had another 2 year warranty on it, posted it to Lenovo and it came back fixed.
Didn't even need to attempt a repair.

Great fix!
I just had the same with a Keysight PSU.
Bought it broken from Romania very cheap and still had full warranty and Keysight Germany did not fix but exchange it for new.
Sometimes we can get lucky.

[Robomeds]

Hard to say since the list is long and over many years.  I did have an easy repair recently that was notable because I have no idea "how did that happen".  I bought a set of Bose Roommate speakers off ebay for $20.  They were listed as not working and the seller said this thing fell out.  The thing in the photo looked like and turned out to be the bridge rectifier out of the power supply board.  Nothing more than putting it back into place and soldering the four leads fixed the speakers.

[MarvinTheMartian]

... Bob's your uncle...

Can someone explain why I seem to be everyone's uncle?     

Bob 

[Berni]

Can someone explain why I seem to be everyone's uncle?     

Bob 

Just be happy you are not Murphy. Everyone hates that jerk.

[KeepItSimpleStupid]

Did the ebay thing too.  I took it apart and said the ribbon cable is crap (yada yada yada) and they gave me a brand new product.   So, you just have to tell them how bad their product is made.   An approximately $400 USD piece of electrical test equipment that I paid like $25.00 for and shipping one way.  I warranty registered the  replaced item as a gift.

So, you just have to tell them how bad their product is made.   This worked for stuff at work too.

[FrankT]

A friend was quote $500 for a new central air conditioner remote control.

A bit of scotchbrite on the battery terminals, and the faulty one was good as new.

[grifftech]

loose wires

[kc7gr-15]

My most recent one was a Teltone telephone line simulator, specifically their model TLE-A-01. Pretty neat device... It can emulate a central office, including sending caller ID data, which makes it ideal for development and test work on an Asterisk PBX.

Anyway... These units have a VF display on the front panel, connected to the mainboard by a flat cable. The one I had was dead, to initial appearances, so I got it for cheap (I thought its power supply might have gone wonkers).

What did I find when I got it on the bench and opened it up? The flat cable for the display had come disconnected. It took less than a minute to reconnect and verify the unit was just fine.

'Tis truly amazing how little effort some folks are willing to put out when something doesn't instantly respond as expected the first time.

[VK5RC]

A recent retro HP 203A oscillator,  check fuse ok,  take cover off -  look -  think (a rare event -  HiHi)  -  those daughter boards look too high -  push them  down,  switch on. +

[Simon Spiers]

It had to be an HP4261 Component tester bought from the USA listed dim display non working.
Thas because it was set to 240V

[Nermash]

Wife said washing machine does not begin to wash after selecting the programme and other options. Figuring the problem could be control board connection issue I gently tapped the front panel Been working fine ever since.

[free_electron]

flipping the switch on the back from 220 to 110 ... went from 25$ to 1500$ ...

[DTJ]

Wife said washing machine does not begin to wash after selecting the programme and other options. Figuring the problem could be control board connection issue I gently tapped the front panel Been working fine ever since.

That's called percussive maintenance. It often works.

[ludzinc]

Rescued the wife when her car didn't start.

Slipped the gear stick from D to P and all was good.

[jonovid]

Wife said washing machine does not begin to wash after selecting the programme and other options. Figuring the problem could be control board connection issue I gently tapped the front panel Been working fine ever since.

That's called percussive maintenance. It often works.

one in every toolbox
 

[ip2k]

+1 for finding a monitor (22" Dell Ultrasharp) in perfect condition with a blown backlight (could see an image when plugged in and shining a flashlight on it). One capacitor was leaking in the PSU section.


Sent from my iPhone using Tapatalk

[CJay]

Windows OS issues. Usually computer problems solve themselves when I show up.
Yes, even at 21st century there are still many people can not use Windows properly and they themselves induce many problems while blaming the computer.

Amen to that, most of my daily life is based around users who are involved in projects to build things like power stations or rail infrastructure but can't work out how to use Word or organise their email.

 

[Legionary]

Not really electronics based, but still a fun return.

Dell 8024F 24 port (SFP+) 10G switch with 8 installed SFP's, but no psu's and a slightly bent faceplate from a local liquidation sale, listed as "not working".

Bought a PSU off ebay, powered on fine. Checked the management console, ports with SFP's were listed in a fault state.
Removed one of the SFP's, it was a fibrechannel SFP. I facepalmed a little at that point.
Removed the remaining fibrechannel SFP's and replaced them with some 10G SFP+'s from the bin.
Worked like a charm.

A very nice ~$75 investment for the home network.

[Bicurico]

Changed two capacitors C848 and C819 on my VU+ Duo receiver, which had problems receiving most transponders. After the replacement, it worked again. Total cost: <1 Euro. Total repair time <1 hour.

BUT: It took me a whole day to actually identify the problem at the receiver... I changed the whole cable distribution on the roof and all LNB's!!! 

Regards,
Vitor

[MatthewEveritt]

I got my current laptop on eBay spares or repair, mouse not working. The fix was to pull off the swollen rubber cap and just use the button underneath it.

Probably the easiest was a fitbit charge for the princely sum of £3.20 with a missing button. Fix for that one was to use a cocktail stick to push the microswitch in order to pair with it, then... um, ignore it. That's pretty much the only thing you need the button for.

[enut11]

Bought a signal generator on eBay that powered up but no output. Traced the signal across the PCB until it disappeared - except that was after a solid copper wire link! On removing the copper link it showed open circuit on the ohm meter. Crazy. A new copper wire link fixed it.
enut11

[P90]

... Bob's your uncle...

Can someone explain why I seem to be everyone's uncle?     

Bob 

Hey, it's bettet than being Chester...  lol 


Replaced a thermal fuse on a close dryer, $5 part (looks like a 25 cent piece) and 10 minutes later, saved couple hundred $$ for a service call.

[TerraHertz]

When I see street-tossed small office machines (photocopiers, etc) I usually grab them, generally to strip for fun and useful parts like polished steel shafts, motors, etc. The rest goes in the recycling bin.

Last week I found a small all-in-one type, a Samsung SCX-3405FW.  Scanner, copier, laser printer, FAX, ethernet & USB. It seemed surprisingly new and clean, like almost just out of the box. Virtually no dust even. I expected there must be something drastic wrong with it, and it would be just more parts.

Problems found: Very drastic indeed! Two tiny corners of torn paper stuck in the paper path. One only reachable by sliding out the drum cartridge. After removing them, it works perfectly. Absolutely clean copy images.

Total time to 'repair' - about 20 seconds, and no tools at all.

Possibly there may also have been a failure in the LCD screen backlight, if it's supposed to have one. Anyway, it's readable without.

[Messtechniker]

Firmware update in two minutes at no cost
on a Philips TV switching itself off an on
constantly in a 5 s cycle. Many such Philips TVs
seem to exhibit this behaviour suddenly for
reasons unknown.

Yours Messtechniker

[SingedFingers]

Just had another one. Old Heath FET bench analogue meter described as untested no mains lead!

Cracked it open, replaced batteries. Sorted

(mains is optional on these)

[Zeitkind]

Loooong time ago, 24" CRT with calibration were quite expensive, about 4k Euro. Got a broken one, "not working, couldn't waste my time, take it!". Powered on, no picture. Opened the case, found a broken input selector switch.. bingo.
But.. 42kg.. 

[tpowell1830]

I just popped it back in, and screwed the case lid back on. Four screws. That was it. This is a really nice projector, very small, with lots of inputs, and even WiFi video input. Also the lamp is LEDs, so no short-lifetime HID lamp to fail.
In the pic showing it running I have the brightness turned down to the very lowest setting.

I had Sony 32" CRT TV and the screen suddenly had video noise all over. I walked over and slapped the case, and, voila, it worked fine for ten more years.

[NottheDan]

Colleague had borrowed an LM30 laser level to get started sorting out some site issues at our production plant related to drainage and was trying to get it to work. He had a fresh set of batteries, put them in, damn thing wouldn't turn on. He took the batteries out again, put them back in, tried again, still nothing. This kept continuing about a dozen times.
I admit, I wasn't much thinking about helping him sort it out but watching him the arrangement of the batteries in the compartment and what I saw from a glimpse if the conductors in the compartment cover (they are basically crossed with a small insulating washer in the centre, not larger than the width of the conductor so at a quick glance it looks like it is a single cross-shaped conductor) made me curious, so I grabbed it and had a closer look. And while I had it in my hand I scraped some corrosion off one of the contacts.
Well, what do you know, the next time he tried it turned on without any problem.

[james_s]

Does a car count as equipment? Plenty of electronics. Well, I once had a Honda Accord and its Check Engine light came on. Pulled out the service manuals and based on the LED blink pattern on the ECU, the flow chart indicated a reboot to the ECU. Did that. Fixed. Problem never recurred.

Laptop that wouldn't boot anymore. Removed dead battery. Booted and ran just fine thereafter.

Let's see, what else. A dead 27" computer monitor. Classic fix with a $0.29 capacitor.

Speaking of cars, back in 2000 I bought a Volvo 740 Turbo with a "bad engine" for $500. It had water in the oil, I found that the o-ring was missing off the dipstick. I changed the oil and installed a new o-ring, water never came back. It's still my daily driver 17 years later.

When it comes to electronics, I've had this sort of thing happen more times than I can count. Frequently I didn't even have to fix something, it simply started working once it was in my hands.

[SingedFingers]

Those 740's are bomb proof. A friend had one with an oil leak. They reckon he drove it a hundred miles after all the oil had gone before he noticed. It did another 120k miles aftet that event before the timing belt went snap at 290k miles!

[CJay]

Most cars will drive a surprisingly long way with no oil before they give up the ghost. They get a bit rattly if they've got hydraulic tappets but they carry on.

[james_s]

The Volvo redblock motors have solid lifters, the design dates back to the mid 70s but it was very modern for its time and I'm always impressed by the robustness. Even if the timing belt breaks it's little more than an inconvenience, the 8 valve motors are of the non-interference design. I've changed a timing belt in my other car on the side of the road once.

[Cubdriver]

Got an HP 5216A frequency counter from the 'bay a few months back.  Not counting, self test unresponsive, displaying all zeroes.  Discovered that the 'frequency standard' switch on the back panel was set to 'external', so it wasn't seeing the built in oscillator.  Flipped the switch to 'internal', and it's now operational.

 

-Pat

[bitseeker]

Got an HP 5216A frequency counter from the 'bay a few months back.  Not counting, self test unresponsive, displaying all zeroes.  Discovered that the 'frequency standard' switch on the back panel was set to 'external', so it wasn't seeing the built in oscillator.  Flipped the switch to 'internal', and it's now operational.

D'oh! Lucky guy.

[SingedFingers]

I love those ones. Similar with my scope. The seller stuck it in X-Y mode because he didn't know how to use it and it looked like it wasn't sweeping. Was fine.

[Cubdriver]

Got an HP 5216A frequency counter from the 'bay a few months back.  Not counting, self test unresponsive, displaying all zeroes.  Discovered that the 'frequency standard' switch on the back panel was set to 'external', so it wasn't seeing the built in oscillator.  Flipped the switch to 'internal', and it's now operational.

D'oh! Lucky guy.

Indeed.     Though the 3450B now on the bench is more than making up for the ease of 'repairing' the 5216A.   

I'll get the 5216A teardown and cleanup pics into a thread one of these years...

-Pat

[MarvinTheMartian]

Got an HP 5216A frequency counter from the 'bay a few months back.  Not counting, self test unresponsive, displaying all zeroes.  Discovered that the 'frequency standard' switch on the back panel was set to 'external', so it wasn't seeing the built in oscillator.  Flipped the switch to 'internal', and it's now operational.

 

-Pat

As Monty Python would say "You lucky, lucky  bastard!"

Deeply envious!   

[Robomeds]

I had a recent one.  Bought a Fluke 73-3 listed as not working.  Turns out the springy part of the 9V battery's terminal was bent open a bit too much.  Squeezed the battery's terminal a bit and it now fit tightly on the meter.  All is well!

[CatalinaWOW]

Got an HP 5216A frequency counter from the 'bay a few months back.  Not counting, self test unresponsive, displaying all zeroes.  Discovered that the 'frequency standard' switch on the back panel was set to 'external', so it wasn't seeing the built in oscillator.  Flipped the switch to 'internal', and it's now operational.

 

-Pat

Just had the same thing myself.  An HP 5359A, no display, power on didn't test display or show error codes.  About to do some serious debugging when I found the switch position.  You would think lacking a reference oscillator would merit an error code, but not on these machines.

[edpalmer42]

A few years ago I picked up an EIP 545A 18 GHz counter.  It worked on the lower two ranges, but not on the 1 GHz+ range.  Turned out you had to connect the internal cables to the right connectors!  Who knew?    Plugged the cables into the right jacks, realigned the YIG filter, which the same idiot probably misaligned, and it works fine!

Ed

[edpalmer42]

Two other easy ones that had similar faults:

I bought an HP 6622A dual output power supply, "tested & working".  Right.  So why was one output dead?  Turns out that the output terminal strip is only held in place by the solder joints.  Rather sleazy for HP.  Resoldered the joints and the dead channel came to life.

I picked up a GW GOM-801G milliohm meter.  It goes down to 20 milliohms full scale, 0.01 milliohm resolution.  Totally dead.  The IEC power jack is soldered into the board.  Three connections.  Guess how many broken solder joints there were?  Yup.  Three.

Ed

[CJay]

Got an HP 5216A frequency counter from the 'bay a few months back.  Not counting, self test unresponsive, displaying all zeroes.  Discovered that the 'frequency standard' switch on the back panel was set to 'external', so it wasn't seeing the built in oscillator.  Flipped the switch to 'internal', and it's now operational.

 

-Pat

Just had the same thing myself.  An HP 5359A, no display, power on didn't test display or show error codes.  About to do some serious debugging when I found the switch position.  You would think lacking a reference oscillator would merit an error code, but not on these machines.

Caused me some grief on a Racal counter too, that at least displayed random gibberish on the LEDs but it turns out the entire counter is run from the reference oscillator so if that's not present you get nothing.

[bibz]

Canon L 16-35mm II lens. Auction said it had taken a fall and the autofocus motor had broken. Took a punt at 300 thinking worse case have some manual focus fun then resell as broken if I couldn't fix it.

Lens arrives, flick the mf-af switch. AF is perfect, lens is still aligned and well. Had a bit of fun and got 900 for it 

[snik]

Today was my easiest repair. I shot a Basetech BT-305 at eBay as a malfuntion returns product for 15€ with no Voltage at Output.

I open the case and look at the pictures what was the fault ... :

[Kilo Tango]

I think my easiest repair was :

Bought a 40" Toshiba TV, symptom no picture, thinking backlight maybe, its worth a go.

It was indeed dead, no response to anything. I think tosh TV's have a 2 year guarantee on them, so I contacted Toshiba, gave them the serial number and asked the question, but they came back saying no its out of the 2 year period. OK so I opened it up and like so many other TV's around it is made by an outfit in somewhere like poland, and the manufacturing date label was still stuck onto the PCB and it wasn't 2 years old. So I emailed Toshiba attaching a photo of the manufacturing label, and a very nice man came and picked it up, special box and everything and Tosh repaired it for free !. 

It s nice if you can get someone else to do all the work !

Ken

[chhrisedwards]

Every repair is easy, only you need practice and experience in repairing, then every repair is like a twitch.

[GreyWoolfe]

The easiest repair just became my HP 3466A DMM.  The function indicator LEDs didn't match the function selection.  Contact cleaner in the gang switches and some vigorous button pushing fixed it.  A nice meter for $30 USD.  Could this even be considered a repair?  Or simply a bit of maintenance.

[texaspyro]

Got an HP 5216A frequency counter from the 'bay a few months back.  Not counting, self test unresponsive, displaying all zeroes.  Discovered that the 'frequency standard' switch on the back panel was set to 'external', so it wasn't seeing the built in oscillator.  Flipped the switch to 'internal', and it's now operational.

I've picked up several HP5370 counters for dirt cheap because of that.  The processor is clocked by the frequency reference.  No ref -> dead counter.

A friend of mine bought a bad Tek 475 scope at a liquidation auction.  He missed the fine print in the auction listing that mentioned it was a pallet sized lot of dead scopes.   The problem... they were all set for 220V.  All were good.   I tested and calibrated all of them and received a 50% cut of the loot.

I wound up with a palette of Pace PRC-2000 solder stations because an auction failed to mention it was a large lot.  When I went to pick up the solder station, a big burly guy showed up pushing a palette jack with a huge pile of the beasts stacked on it.  I had to make a couple of extra trips to schlep them all home. (BTW, new they sell for around $6000 each with all the accessories).

[bitseeker]

Could this even be considered a repair?  Or simply a bit of maintenance.

One man's maintenance is another's repair. Unfortunately, too often even these levels of intervention are generally treated as catastrophic failures destined for the bin. So sad.

[Berni]

A good example was the photocopier that Dave found in his dumpster room.

He had a peek inside and found a paper jam. Once the rebellious piece of paper was removed the photocopier worked just fine and still had plenty toner left in it.

[CJay]

I've picked up several HP5370 counters for dirt cheap because of that.  The processor is clocked by the frequency reference.  No ref -> dead counter.

A friend of mine bought a bad Tek 475 scope at a liquidation auction.  He missed the fine print in the auction listing that mentioned it was a pallet sized lot of dead scopes.   The problem... they were all set for 220V.  All were good.   I tested and calibrated all of them and received a 50% cut of the loot.

I wound up with a palette of Pace PRC-2000 solder stations because an auction failed to mention it was a large lot.  When I went to pick up the solder station, a big burly guy showed up pushing a palette jack with a huge pile of the beasts stacked on it.  I had to make a couple of extra trips to schlep them all home. (BTW, new they sell for around $6000 each with all the accessories).

Same as Racal 199x counters, if there's no reference there's no CPU clock, simple as reseating the Bliley crystal in one OCXO on mine, both had blown 630mA fuses as well even though they were set for the correct voltage. Simple fixes which got me some lovely counters.

Nice win on the 'scopes too, unfortunately it's more likely to be the other way round here in the UK, equipment set for 110 and blown up because it's been fed 240.

[CJay]

A good example was the photocopier that Dave found in his dumpster room.

He had a peek inside and found a paper jam. Once the rebellious piece of paper was removed the photocopier worked just fine and still had plenty toner left in it.

People's attitudes to printers and copiers are weird though, they get ridiculously overwraught about them.

Even if you can prove they don't fail as often as they think it becomes almost impossible to turn the tide of ill will so sometimes it's just easier to replace them (that's not to say I've not just shuffled them around departments after some judicious maintenance though...)

[GreyWoolfe]

Could this even be considered a repair?  Or simply a bit of maintenance.

One man's maintenance is another's repair. Unfortunately, too often even these levels of intervention are generally treated as catastrophic failures destined for the bin. So sad.

Thankfully, it ended up at the surplus store instead of the bin.  That gave it a new lease on life.  I am waiting for payday on Friday, they have an HP 13 MHz function generator for $40 USD that has 2 broken button caps on it.  A small screwdriver will operate the switches.  I plan to bring my DSO and a cable to see if it actually outputs anything.  I do have a frequency counter to go with it If it works and I decide to buy.

[bitseeker]

People's attitudes to printers and copiers are weird though, they get ridiculously overwraught about them.

...just shuffled them around departments after some judicious maintenance though...

That's excellent!

I am waiting for payday on Friday, they have an HP 13 MHz function generator for $40 USD that has 2 broken button caps on it.  A small screwdriver will operate the switches.

Very nice. Hope you score it.

[james_s]

I've lost count. I've received "broken" equipment that turned out to have no fault at all. I was once given a car that had broken down and I fixed a solder joint in the fuel pump relay in about 5 minutes and drove it home.

[TheWelly888]

Slightly tricky diagnosis but a dead easy repair of an electrical fault on my car several years ago.

I had a Ford Fiesta and one day the rear wiper and screen heater would not work at all. Fortunately I had a Haynes manual for that particular model and it included a circuit diagram - I found that the three contacts in the hatch were all used, two for the wiper and wiper parking and the rear heater but I realised that the common return were all through the hinges of the hatch into the body of the car. The hinges were rusty and so must have broken the circuit - all I had to do was to apply copper grease to the hinge rubbing faces and work them. They all worked perfectly afterwards!

Sadly I wrote the car off by driving off a sharp bend into a field a few months later.

[texaspyro]

I had a Ford Fiesta

My sincerest condolences...   

[Gyro]

Yes, that was a really lousy design. If my son's Fiesta was anything to go by, it contributed to rusting of the tailgate too! On his, the shaft seal leaked too and the wiper motor gears filled with water. The auto-return switch segment on the gear was made of....... wait for it....... Steel! 

[Oldtestgear]

I used to do contract repairs for a couple of Cal. Labs. One of these had a "faulty" HP 4274A which was offered to me for £20. This was about 8 years ago & prices were higher. Got it home, pulled the covers off & removed the (very flat) battery backing up the SRAM. Message immediately disappeared & it has been working ever since. The battery only holds data for limits etc. & was an option. Working & back in the case in about 15 minutes.  Certainly the cheapest repair I have done.

Phil

[bitseeker]

Hehe, nice one, Phil.

[andy2000]

I've had too many to count over the years.  The general theme is that people usually suspect a major problem when it's something simple.  On the other hand, they usually say it's something simple when it does have a major problem....  I guess simple things like bad caps, or broken solder connections cause things to be completely dead and people assume the worst, but major problems like a bad acquisition board just cause a few errors in the self test.

The easiest repairs are the ones where you can't find anything at all wrong.  My Fluke 189 came from a lot of e-waste, and I never did find a problem with it.  Probably user error, bad batteries, or an employee who wanted a newer model.

Earlier in the year I bought a fairly new 60" Samsung plasma TV for $30 off Craigslist.  When I got there, I discovered he was a tinkerer who had tried to fix it.  He said his boss gave it to him because of an intermittent issue that eventually became full time.  He couldn't see any obvious problems (like bad caps) so here it was.  I didn't have high expectations, but it was cheap.  When I took the back off, I quickly narrowed it down to a missing Vs supply.  As soon as I pulled the power supply, I found a very obvious bad solder connection on a power transistor.  I confirmed that the transistor wasn't shorted, and resoldered it, and it's been working fine since then. 

[Neomys Sapiens]

Oltronix B32-10 Laboratory Power Supply. Sold on Ebay as 'defective'. further stating, that 'voltage breaks down about mid-range'. There were even photographs with real good resolution. Looked at them, determined that the recessed front panel pot for the overvoltage protection (crowbar) is set about mid of it's adjusmend range.
Bought the unit, set crowbar to full CW, tested: GO.

Rohde&Schwarz Power Supply NGR20 on a Ham fleamarket, the seller started fo fidget when asked if it works by someone he obviously knew. Originally, he wanted 100€ for it. I jumped in, paid 40, came home, looked at the unit, moved the slide switch, which selects Sense int/ext two or three times to and fro: working flawlessly since then.

Siemens Multizet A1001 DC electronic multimeter, advertised as defective 'doesn't measure'. Was shown to switch on and give range indication on the secondary LCD. This LCD has a fuse symbol, which is shown when fuse is blown (or missing). This was clearly lit. Got the instrument, checked fuse (missing), replaced with the untouched, original spare fuse from the spare fuse holder: working, all nominal and within spec.

[Neomys Sapiens]

'Broken' M22520/7-01 Daniels Milspec crimping pliers (the green mid-range one): received and saw two-part spring in release mechanism. Two-part spring? Broken spring! Incidentally, I had much business with the company representing them in Germany, asked for a spring, received one, replaced it and DONE.

[iampoor]

Every repair is easy, only you need practice and experience in repairing, then every repair is like a twitch.

Sounds like you do not have much experience with repair then. 

[vk6zgo]

 ::)A couple more easy ones:-

HP N&D set kept blowing Mains fuses.
Opened it up, found that an internal panel could sometimes flex enough to hit the back of the fuse holder.
I glued a piece of perspex on the panel just behind the fuse holder.*

Icom IC 910 Ham Transceiver made clicking noises & overheated.

Repositioned the ribbon cable which was fouling the fan.

* Thinking back, either HP stuffed up the connections on the fuse holder, ( the incoming Mains should be on the centre pin), or it was the rack fuse that was blowing.

Too long ago.

[SaabFAN]

PC had very erratic behavior - it would sometimes run for hours and then suddenly shut off, or power on and immediately power off again.

On a hunch I measured the voltage at the power-button pins and discovered that the power button didn't disconnect properly. Even when not pressed, it still had a resistance of some 10k Ohm. Enough to pull the Powerbutton-Input low enough for the Mainboard to occasionally trip and regard the signal as the button being pushed.
Repair was easy: Set power-supply to 15V, 1A and connect the power-button to it. Zapped it and since then no more problems

[DrGeoff]

Plasma 46" TV from the roadside. DOA.
30 minutes and a 6 cent diode in the PSU and we have a nice working TV

[Tom45]

When I was an EE student in college over 50 years ago, I was asked to help with the repair of a Knight stereo amplifier another (and younger) EE student had built from a kit. It had never worked, so it was an error in building the kit.

Several guys had tried for days to find the defect, and they were referred to me after having given up.

I grabbed a screwdriver and with my finger on the shaft, I touched each grid starting from the output tube and working back towards the input stage. When I no longer heard hum and static when touching a grid I knew which stage wasn't working. A close inspection of that stage showed a solder blob that was shorting the signal. I pointed out the blob and told the guy to fix it.

They had spent several fruitless days, but I had the answer in a few minutes with no test equipment other than a screwdriver and my ears.

Those Knightkit amplifiers usually had some audible hum. I improved quite a few of them by replacing the power supply filter caps with larger values.

[Cubdriver]

I've had too many to count over the years.  The general theme is that people usually suspect a major problem when it's something simple.  On the other hand, they usually say it's something simple when it does have a major problem....  I guess simple things like bad caps, or broken solder connections cause things to be completely dead and people assume the worst, but major problems like a bad acquisition board just cause a few errors in the self test.

The easiest repairs are the ones where you can't find anything at all wrong.  My Fluke 189 came from a lot of e-waste, and I never did find a problem with it.  Probably user error, bad batteries, or an employee who wanted a newer model.

Earlier in the year I bought a fairly new 60" Samsung plasma TV for $30 off Craigslist.  When I got there, I discovered he was a tinkerer who had tried to fix it.  He said his boss gave it to him because of an intermittent issue that eventually became full time.  He couldn't see any obvious problems (like bad caps) so here it was.  I didn't have high expectations, but it was cheap.  When I took the back off, I quickly narrowed it down to a missing Vs supply.  As soon as I pulled the power supply, I found a very obvious bad solder connection on a power transistor.  I confirmed that the transistor wasn't shorted, and resoldered it, and it's been working fine since then.

As for the ones that are supposed to be easy, they're often a laugh.  The seller says "it's not working, but it's just a blown fuse."  I think "If that's all it is, then why don't you replace the less-than-$1.00 fuse and then sell it as working?"  Seems you'd get a lot more than that $1.00 invested in that fuse as a return for selling a working unit vs a non-working unit.   

   I was born at night, but it wasn't last night...   

-Pat

[LazyJack]

As for the ones that are supposed to be easy, they're often a laugh.  The seller says "it's not working, but it's just a blown fuse."  I think "If that's all it is, then why don't you replace the less-than-$1.00 fuse and then sell it as working?"  Seems you'd get a lot more than that $1.00 invested in that fuse as a return for selling a working unit vs a non-working unit.   

   I was born at night, but it wasn't last night...   

-Pat

Yeah, it is pretty much the same, when people selling cars, and say the AC just needs to be refilled with refrigerant to get it working. Any time I say, OK, then please have it refilled and deduct the refill price (which is peanuts...) from the price of the car, they always miraculously back down from the sale. Without of course admitting the gaping hole in the AC radiator or the seized as rock compressor.

[CatalinaWOW]

Of course I have sold a few as non working because the fuse holder was missing, difficult to replace and I just didn't want to fool with it.  No claims on whether anything other than the fuse is defunct.

This would be a dumb move on my part if I was running a business, but it is a hobby and if it isn't fun it isn't happening.

The same happens in reverse.  I have done several non-economic repairs because I was interested in the result or enjoyed the challenge.

Bottom line - if you want a really smoking good deal you have to take some chances.  In Yankee vernacular you will whiff a few balls between the home runs.

[james_s]

I've had too many to count over the years.  The general theme is that people usually suspect a major problem when it's something simple.  On the other hand, they usually say it's something simple when it does have a major problem....  I guess simple things like bad caps, or broken solder connections cause things to be completely dead and people assume the worst, but major problems like a bad acquisition board just cause a few errors in the self test.

I observed that many times when everyone still had CRT TVs. If it won't power on at all, I'd hear "it's probably just the switch" which it never is, the one I'd hear a lot is "the picture tube is going out" which was never the case.

Then on sets that really did have a worn out CRT "it just needs an adjustment!"

[CJay]

I observed that many times when everyone still had CRT TVs. If it won't power on at all, I'd hear "it's probably just the switch" which it never is, the one I'd hear a lot is "the picture tube is going out" which was never the case.

Then on sets that really did have a worn out CRT "it just needs an adjustment!"

'it's just the picture valve whats gone'
Solid state sets, you really don't want to have to replace the picture tube.

'the bloke down the road said it would be cheap and he knows cos he was in radar during the war'
Hasn't touched anything electronic since the war but still knows everything.

'I'd fix it myself only I don't have time'
Has been inside and twiddled everything, probably also replaced the fuse with a nail or aluminium foil.

[vk6zgo]

I've had too many to count over the years.  The general theme is that people usually suspect a major problem when it's something simple.  On the other hand, they usually say it's something simple when it does have a major problem....  I guess simple things like bad caps, or broken solder connections cause things to be completely dead and people assume the worst, but major problems like a bad acquisition board just cause a few errors in the self test.

I observed that many times when everyone still had CRT TVs. If it won't power on at all, I'd hear "it's probably just the switch" which it never is, the one I'd hear a lot is "the picture tube is going out" which was never the case.
Then on sets that really did have a worn out CRT "it just needs an adjustment!"

There is a reason behind the "just the switch" idea.
In many cases, the switch mode PSU loses its start circuit, but if you quickly switch it on & off, you can often get the rotten thing to start.
They keep doing this, until it doesn't work any more, in the meantime, they have wrecked the switch.
The TV set comes in as "faulty switch".

The first few times, in my innocence, I just replaced the switch.

As I worked at a TV Studio, I didn't really have the option of rejecting jobs.
We decided to "out source" some "domestic" TVs & concentrate upon Broadcast standard stuff.
This had mixed success, with some total disasters which had to be "fixed after the fixing" after they came back.

Even the good repair shops had their moments, though.
With one set, we did "first in"  checks, narrowed the fault down, attached a sheet with this information, & sent it off.
When we picked it up, it had their tag on it, which simply said "doesn't work"!

[petepdx]

Ditto on the 220V. Keithley current source. Slide switch clearly showed was in the 220V posistion

-pete

[maggo]

My easiest fix is a draw between an AKAI AM-75 Digital Integrated Amplifier and an ELAC Subwoofer

AKAI:
I got it very cheap from my neighbour because it did not work properly. After turning it on, it constantly went off and back on again.
Found a broken solder joint on the main PCB. Easy to see with the naked eye.
Resoldered and that was it.
After a little while I also changed the relays for the speaker outputs.

ELAC:
Same thing here. Faulty solder joint. Fixed and good as new.
To be honest I fixed several more solder joints. Some were looking very suspicious...

But yeah. Almost zero effort for two pieces of high quality audio gear. 

[HalFET]

Biggest ratio was on a Keithley 130 multimeter, someone had tried to power it up with a power supply but switched the leads. Took the whole of 5 cents to replace the protection diode.

[soubitos]

Customer arrives in shop in panic... brings in a pc with just released Pentium 4 3Ghz Pres-hot Intel Inside, NVidia graphics again top notch, raptor HDDs not the SSD bulshit etc, a 1500-2000 euro machine maybe more with the "extras"...
Save me, my computer won't boot, its says, insert system disk on a black screen (or something like that)......

Ok.... you are good to go.....

Customer offers to pay, i charge him nothing leaves happy but embarrassed....

Oh, the old FDD days.... leave one inside and you might... not boot ever again!~LOL

[neo]

Well it was hard to figure out but was an exceedingly simple fix. The cord was part of the multi meter and had gone open intermittently, and the HV capacitor inside it, for the nixie tubes, vaporized when i touched it.

[onre]

Old thread, but had to brag:

A couple of weeks ago I "fixed" two oscilloscopes in a single day. One required locating and turning up the separate "analog brightness" knob to get the analog side tracing again, another needed a firm press of "INT/EXT" switch to get internal triggering "working" again. 

[stefan_o]

My easiest repair ever was a Sennheiser SKM 5000 professional wireless microphone several years ago (there were about 500€ used in good condition back then). Bought it as defect with weird rumbling noise for about 100€. Opened it, directly spotted a broken solder joint at a big SMD tantalum capacitor, fixed it, put it back together, works perfect. Repair took less than 10 minutes 

For the computer builders here: did you ever have the experience that your friend's computer went dead, they couldn't fix it, and the computer magically fixes itself after you show up?

Yes! I think one of the main reasons was overheating, these old towers/desktops could suck in massive amounts of dust into the heatsinks that eventually even blocked the fan. So my initial response to the question "what tools do you need to fix that" after a pc "died" was: most likely just a vacuum cleaner.

[onre]

Alesis Quadraverb multi-effect device from dumpster: opened it up and reattached the display ribbon cable.

[edpalmer42]

Easiest possible repair - I didn't do anything!

A friend had a dead big screen plasma TV.  He said that it quit working some months ago and asked if I would inspect the board if he removed it from the TV.  I said sure.  Later he told me that when he went to remove the board, he found that some of the mounting screws were loose, so he tightened them.  Problem fixed!

Should I send him an invoice for the repair?  Without me, it never would have happened!   

Ed

[Teledog]

Reprogramming an Icom HT radio that was programmed out of band (it was flashing red/blue)
Maybe 2 minutes?

[coromonadalix]

bought an electronic voice synthetised chess game for 5$,  put an 25 cents transistor because the voice was not good, made an 600$ profit on ebay it was a rare item to my total stupefaction  

[bitseeker]

Wow, easy repair plus major score.

[ScottM]

By far the easiest and also biggest sigh of relief...

On call tech for the weekend. Usually nothing happens. Maybe a call for resetting something, 10 minutes on phone is typical.

Phone rings. Customer is bonkers. " system is dead, you need to come right away!"

Me:"are you sure it has power?" (Client is known to use breaker as switches)
"Oh, yes it is clearly marked - do not turn off"
"Ok I can come but it is the weekend and I'm 3 hours out. We bill travel time and I need to go to the shop and get some parts."
"Please come guickly"
So since the system is total garbage I go to the shop and grab several boxes marked 'kludge'. Drive 3 hours cursing all the way at my bad luck for getting this call. It can never be fixed. Arrive in bad mood. Yup system is dead. Plug meter to mains (you know the reading right?)
Reach over turn on breaker as the panel is just arms length away.

Client: "So there is no charge because you didn't fix anything?"

It sure was a sweet 3 hour - billable - ride home.

[precaud]

Not necessarily the "easiest" but pretty easy. I've had a Lecroy 9450A DSO sitting around waiting to be diagnosed for 6 or 7 years. I got it cheap back then because it powers up to a blank screen and no activity. It has a very visible gash/deep scrape on the front bezel from some careless handling, so resale value would have been compromised, which lessened my motivation to fix it. On the other hand, it has the WP01 math and WP02 FFT options installed, which (as I later learned) turn it into a quite capable 300MHz spectrum/network analyzer.

So a couple weeks ago I opened it up for another look. Power supplies checked out good. No sampling clock signals. I pulled the cpu card out and saw that the Eurocard connector "fingers" were half clogged by dust bunnies! That can't be good. Easy to see why - the cooling fan blows right into the channel and cpu cards (with no air filter!), the Eurocard connectors are situated right there too. I checked the nvram backup battery on the board and it was dead. So I cleaned the entire board and put in a good 3V lithium battery. Pulled the rest of the cards and they were similarly dirty with dust-clogged connectors. Put it back together, turned it on, and there were signs of life - the crt and some front panel lights blinked momentarily. That means the display probably works, and the cpu was trying to boot it.

While poking around, I remembered seeing a Reset button on the bottom of the rear panel. I pushed it. Nada. Nothing happened.

Next day, while reading through the service manual for more troubleshooting clues, I happened on a paragraph that described the reset button. It warned that the nvram contents are initialized by a reset. Sounds good to me. And you can't just push it - you have to hold it in for a few seconds until you hear a beep, which signals that then the cpu has reset everything and then reboots. So I tried it and -voila - the 9450A came to life and has worked fine ever since! Some bad constants in the nvram were causing it to hang. The crt is excellent with no visible burn-through, so there's plenty of life left in it. I really like these Lecroy scopes and have decided to make a place for it on my bench.

If only all repairs were this easy.

One drawback to the some of the 9400-series is that they put the power switch in the back panel. (Huh? What were they thinking?) That means I can't put it on (or under) a shelf among other equipment. It's gonna take some bench reorganizing to make a place for it that allows me to reach the switch.

[ddwilson]

when I worked at a hardware store someone returned a multi-meter after it got claimed as defective I took it home and installed a battery package even said battery not included.
 

[SeanB]

Inverter welder from the local Makro, bought as "shop soiled", and also rattled. Got an even better price from them ( bought 2 for half the price of one), and as it was demo stock I only got a single set of leads. No problem, tried both and fixed the rattle, EMI choke on some sense wires had broken in half, and i did not bother to replace it, too much PT to get a replacement one from a CFL lamp to slip on the loom there.

So, took the one with leads, gave it away, and later on got a pair of those 9.5mm twist plugs and used them on a set of spare welder leads from an old oil filled welder I had, and now have better leads than the unit came with originally. First job with it was repairing washing line poles, as they needed to have some braces installed to keep them upright. then a little testing and I am slowly learning how to weld thin sheet plate with it, the HF start really makes it easy to weld at low current and not burn through the plate too much.

[Bud]

Not exactly repair since it did not touch my hands but still rather funny. While browsing eBay I came across a HP frequency counter that the seller was advertising as Not Working, for parts. When switched on, the device displayed "NO OSC" and did not do anything. I happened to have exactly same counter model and I knew you get this message if you switch the device to use external 10MHz reference clock before you connect the external clock source. The message means No Oscillator, which makes sence. There was a photo of the back of the device that the seller provided, i checked the photo and sure enough the clock switch was in "External" position.    So the "fix" for it would be to flip the switch back to Internal clock.
I did not bother contacting the seller. I did not need a second counter and some other buyer might have made a good deal.

[envisionelec]

Behringer iNuke 3000DSP. The rack in which it was installed took a lighting hit to GND. Insurance already covered the replacement...

A single ESD1 diode was shorted across the output FETs. Replacing that restored full operation. I am still surprised the damage was so minimal!

[CJay]

I am still surprised the damage was so minimal!

Lightning can be very strange, when I repaired televisions for a living we got a call to go and look at a few houses on one street where there had been a lightning strike.

We could tell which house had been hit because there was a sooty trail down the wall where the antenna downlead had been along with a flashover tinge on the brickwork, we reckon it was vaporised copper.

In the garden there were thousands of tiny beads of aluminium, that was the TV antenna from the roof.

The only damage inside the house was TV itself which worked perfectly after we resoldered the few inches of coax from the Belling Lee socket back onto the socket and the tuner.

The neighbour's house, every appliance in the place was destroyed yet there was no visible sign at all of damage, several other houses had similar but less extensive failures.

[peteb2]

Had a slide-decker truck arrive at my home one morning completely out of the blue... It had a car on the back and its owner traveling in the truck cab with the truckdriver. She lived not far from me (i'd met her a few times at local friends BBQs and parties and once had a chat with her etc)

Story goes that her car had refused to start for the last 3days (in the morning) and so she left it and took the bus. For some reason she chose to get her car delivered to a garage on the 4th morning of the drama but as she traveled in the truck with the poor driver she had a massive brain-fart and decided they had to drop in on the way and see me, because she suddenly remembered i like "playing around on old cars and those coloured wires" and everyone had told her it must be an electronic fault. ....

I was about to leave for my work too but humored her as the truck driver basically rolled his eyes... I had a look at things, climbed up on the deck of the truck and clambered into the car, pushed the keys into the ignition and turned them. The dash cam up but it just would NOT crank the engine over... By natural process when you've done something a million times, and the car having an automatic transmission i selected P and because the shifter was sitting in D. The engine fired and ran the instant it cranked... 

I was stunned that the towey had probably not checked the fault and simply put it up on his truck and i was doubly stunned she'd not bothered to do a work-through as in a basic procedure should your car not start.

Anyway i left her to sort out the cost of her car being loaded and carried a couple kms to my home and the callout fee.... The towey unloaded her car and she headed off to her work. Haven't talked to her since and it was over 10yrs ago!

[scopeman]

Let's see:

Somewhere I have pictures of all of this stuff but I'll be darned if I can find it.

Wavetek 39 - $25.00 eBay. Powers on but display blank. Popped the cover on it and the resistor for the reset circuit (through hole) had one lead touching the pad. Cleared the pad and soldered the resistor in place and of course it worked like a charm!

Fluke frequency 512MHz counter - won't count. $12.50 eBay. Cleaned internal/external time base switch. Perfect!

LeCroy 224 Waverunner. $110.00 eBay. Powers up no display. Bad 3 terminal regulator in power supply. Plus the unit must have been used in a coal mine!

Fluke 8060A $27.50 eBay. Clean-up and replaced caps. Still dead on cal after all these years.

General Radio 1656 Bridge. $159.00 Sold as perfectly working (is in mint condition - looks like never used). One range would not null. Found a pass through wire on the range switch was never soldered at the factory. It appears that the range was never used. Soldered and perfect!

HP8753C/8702A Network analyzer. After cal if you zoomed in on the smith chart the calibration point would move around. Turns out that in the 85046A S parameter test set there is a clamping set screw that locks the leftmost connector ground to the mounting point. Tightened the setscrew and the problems go away. Cal good to the noise level of the unit.

Tek 475A - IBM branded scope with probes and cart. Really clean but dead. Bought for $30.00 at a local hamfest. Had a blown (shorted) bridge on the 8V power supply. Amazingly enough the caps were good. Soldered in a new bridge. Fan a little noisy but works perfectly.

Tek 422 - AC powered model. Older style with nuvistors. Really clean but no trace. Shorted cap in the HV power supply. Replaced Cap. This is my loaner scope when someone needs to borrow a scope.

Tek 2220 bought for $20.00 at a hamfest, untested but owner claimed no sweep. Got it home on the bench, powered it on and set the trigger from Norm to Auto scope sweeps. Not a thing wrong with it. Great scope for audio work.

HP3310B Function Generator. Pulled from a scrap pile of instruments from a place I worked at years ago. No output on any setting. Rotating the phase control on and off the Free Run position causes the generator output to "burp". Cleaned the control contacts for the Phase/Free Run control restores normal operation.

Tek 453A - Given to me by a friend that no longer wanted it. Claimed that the Delayed sweep function did not work properly. Sweep Length control in the wrong position.

I could probably list dozens more. Sometimes fixing things is more fun than using them!

Sam
W3OHM

[Twoflower]

20 years or so ago. Friend of mine got for a beer a 6-CD changer for a car. The original owner said it jumped all time. Nevertheless my friend asked me to install it in his car. While doing so I asked my friend if he knows which orientation it was mounted originally. And yes the damping setup was wrong (horizontal vs. vertical mounting). Full success.

But the damn thing paid back later. A couple months later said friend showed up telling me the changer ate a CD and reported an error code. So opening the changer and moving the gear-work mm by mm to even slower moving the CD out of the drive. After 30 minutes fiddling on the gears the CD was finally out. While closing the thing I noticed a label in the inside of the lid. It was the instruction how to eject the CD if the same error code is reported: Just slide a plastic card in and the CD will be spit out 

[anachrocomputer]

Saw an HP 3325A synthesiser function generator the other day for £150, sold as non-working. Too much, I thought, and waited. The seller dropped the price to £100 and then I began to consider it. "Will not power up". Hmm... Power supply fault? Check photos, and eventually realise that it's set to 120V, and the seller was testing it in the UK (240V). OK, so maybe the mains transformer is burned out? And the seller knows this and that's why it's for sale? Or they don't know that and it's a simple fault but they don't do repairs?

Well, I couldn't resist giving it a go, and when it arrived, sure enough, it's set for 120V. And the fuse is blown. One new half-Amp fuse, and a couple of switch settings inside, and it works! Tested as far as I can with the scope and even plugged in an HP-IB interface to try that out. All OK!

Winner winner, chicken dinner!

[bitseeker]

Glad the fuse died first! Doesn't always work out that way.

[NiHaoMike]

Our lab at work inherited a really nice 1KW switching lab power supply that wouldn't power on.

Turns out the front power switch had failed open. One new power switch later, and the thing works a treat!
Better yet, the power switch was wired up using quick connect plugs. No soldering required!

A very long time ago (when CFLs were just coming out and somewhat expensive), my mom got a fluorescent light at a thrift store for $5 or so. The problem? A bad switch. Bypass it and plug it into a switched outlet.

About a year and a half ago, I scored a WD AC1300 (actually AC1750) router for $15, was sold as a returned unit that "worked but made a lot of noise". Swap the fan with an identical looking one from the parts bin and it was working like a champ. Until now when I noticed the fan is starting to fail again. The fan in the router always starts to fail when the mining cluster it serves has some real work to do, right? Temporary solution is to place an external fan to keep it cool until I can find a replacement.

[mscreations]

Not electronics related, but I service forklifts for a living. One Thanksgiving while shopping at Walmart, I got called out for an emergency repair. At the Walmart. Walked over while the wife finished shopping and took a look. Someone had turned the key to their scissor lift to off and removed the key. No one there had a key. I pulled mine out of my pocket, turned it on and told them we would send the bill. I got paid 4 hrs (minimum call out time) at double rate ($54/hr) for five minutes of my time.

Electronics related, I got 4 computer monitors from my employer that were 18 months old. Took first apart and found blown caps in the power supply. Replaced them in all 4 units and now have 4 monitors for my computer. They've been flawless since they were repaired.

[DDunfield]

Tektronix TDS380 - Engineer at a local company discarded it because "Channel 1 was Wonky".

Turns out someone along the line had replaced the Channel 1 BNC connector with a non-Tektronix one which effectively reversed ground and probe sense (Probe sense ring connected to ground, outside of BNC connected to probe sense).

Took me a couple weeks to obtain the proper Tek part, but once replaced - scope is like new again.

Dave
 

[TheDefpom]

Mine was probably a hp microwave frequency counter, picked it up for about $300, all I did was clean all the card edge connections and replaced 1 capacitor, and it came back to life, ended up selling it for over $1000

[Arek_R]

Owon SDS5032E Digital Oscilloscope, sold as faulty, not working, customer return, physical condition - like brand new.
Got it from ebay for £65, working new one is between £250-£300.
It was powering on but not finishing boot process to UI.
All I had to do was to was to update the firmware using dedicated software, it was not available, but after one month someone got hands on this software and released it, so I update it, and it works just fine!



Kane-May km330 themometer, got it from ebay for £0.99, sold as used, faulty, without the k-type probe.
Brand new is like £100
After I received it and connected it with my probe, it works just fine, dude probably just had broken probe...

[slurry]

That have to be a lab power supply that would'n turn on,
i reached back and pushed the IEC power-connector in fully, then the power supply worked just fine. 

[GreyWoolfe]

That have to be a lab power supply that would'n turn on,
i reached back and pushed the IEC power-connector in fully, then the power supply worked just fine. 

Over the years, I have had quite a few service calls like that.  Or someone kicked the plug in the surge protector just enough to partially dislodge it.  Or the power cord came out of the power supply body.  I would always ask if they checked all the connections and can they do it again and was always assured that they did.  Service solution?  Customer error.

[joeqsmith]

My Sony DSC-RX10M2 decided to stop recording today.    I had bought a Fotga external trigger that I modified with an opto-coupler so I could trigger the camera with various test equipment. 

If I used the trigger button on the camera, it worked fine.   I took apart the Fotga to see if a wire had perhaps broke.   I tested it outside the case and all the signals seemed fine. 

I then tried to trigger it again using the camera's built-in button.  This time it came back with an error that the card was full.   I am not sure why it would trigger that one last time with the camera's built-in button but not the with the external trigger. 

Fairly easy repair, reformat the card.   

[SeanB]

Glad the fuse died first! Doesn't always work out that way.

Common failure on certain avionics was "fail self test", and when i got the wooden transit box and opened it i could smell the cooked insides even though they were hermetically sealed units. Failure was that one of the diodes on the 6 small 3 phase bridge rectifiers that provided internal supplied went short circuit at some time. MC44 diode, 6 per bridge. The 5V rail going short would blow the 1A mains fuses, because that rail had to supply 15A to the unit, so no issues there, but the other rails however would not draw 1A on the primary side into a short. Would work with 1 diode short, just high ripple on the power rail unregulated side ( I checked every unit with a scope looking for that odd shaped ripple on the rails quickly enough), but if a second one went short then the transformer would have a high current flow in the winding, and would gradually heat up.

As the unit was hermetic, this meant no smoke or flame, just a transformer making toxic fumes and eventually getting hot enough internally to destroy the interwinding insulation, typically after dumping a load of liquid melted thermoplastic and varnish byproducts into the case and into the cooling fan. Only then would the primary current be high enough to blow 2 of the 3 1A solder in fuses that provided protection, and the built in test light relay would drop out and show a fail on the master caution panel. I did order some spare power supplies, and I guess Fraser would know the route they took to get there, along with the price of them. Never seen that many digits in an invoice before, for something that was basically fist size, and which I guess was about the price of Promethium per gram, as it was a lot more than Gold, Platinum, Palladium or Rhodium..

[jtu]

Cleaning out dead ants and changing fuse on ~300Eur automatic gate controller: https://www.eevblog.com/forum/repair/nice-automatic-gate-controller-and-ants/

[kulla]

Bought older (but still great) fishfinder Lowrance LCX series that was rebooting constantly.

It turns out that as it had mechanical PATA hard drive inside, humidity got it, so when it starts it would try to spin the disk which would then draw too much current and system would reboot.

Removed the disk and everything worked like it should. Used it for a two years and sold for 3x price of what I paid for it.

It still works

[vk6zgo]

Glad the fuse died first! Doesn't always work out that way.

Common failure on certain avionics was "fail self test", and when i got the wooden transit box and opened it i could smell the cooked insides even though they were hermetically sealed units. Failure was that one of the diodes on the 6 small 3 phase bridge rectifiers that provided internal supplied went short circuit at some time. MC44 diode, 6 per bridge. The 5V rail going short would blow the 1A mains fuses, because that rail had to supply 15A to the unit, so no issues there, but the other rails however would not draw 1A on the primary side into a short. Would work with 1 diode short, just high ripple on the power rail unregulated side ( I checked every unit with a scope looking for that odd shaped ripple on the rails quickly enough), but if a second one went short then the transformer would have a high current flow in the winding, and would gradually heat up.

As the unit was hermetic, this meant no smoke or flame, just a transformer making toxic fumes and eventually getting hot enough internally to destroy the interwinding insulation, typically after dumping a load of liquid melted thermoplastic and varnish byproducts into the case and into the cooling fan. Only then would the primary current be high enough to blow 2 of the 3 1A solder in fuses that provided protection, and the built in test light relay would drop out and show a fail on the master caution panel. I did order some spare power supplies, and I guess Fraser would know the route they took to get there, along with the price of them. Never seen that many digits in an invoice before, for something that was basically fist size, and which I guess was about the price of Promethium per gram, as it was a lot more than Gold, Platinum, Palladium or Rhodium..

Back in the day, I worked on a Pye  UHF TV Transmitter which used stupidly under rated EHT rectifiers.
These things would blow if you looked sideways at them.
Getting replacements from the UK took forever--a fast (hell, no) a slow windjammer would have beaten their best efforts.
Dunno how much they cost, wasn't my department.
Meanwhile, NEC used over rated rectifiers which lasted for decades.

Later, in another job, we had  mainly Sony picture Monitors, but also a few Barco ones.
Sony parts availability was generally overnight, whereas you could probably budget a month or more for Barco.
I think some European companies "piggy-backed" their packages on someone else's container, which didn't move until it was full.

[IAmBack]

Adjustable 15A 25V bench PSU unit that "stucked" on 13.8V was bought by me in a fraction of price. Problem? Switch on the bottom of the unit that sets constant voltage to 13.8V was turned on. So... RTFM.

[Arek_R]

Adjustable 15A 25V bench PSU unit that "stucked" on 13.8V was bought by me in a fraction of price. Problem? Switch on the bottom of the unit that sets constant voltage to 13.8V was turned on. So... RTFM.

What kind of PSU has switch for such a weird value?

[helius]

What kind of PSU has switch for such a weird value?

One intended for float charging lead-acid batteries, or operating mobile radio equipment at 13.8V, said equipment designed for the output of a vehicle's alternator. You also sometimes see 14.4V which is for equalizing lead-acid batteries.

[IAmBack]

Adjustable 15A 25V bench PSU unit that "stucked" on 13.8V was bought by me in a fraction of price. Problem? Switch on the bottom of the unit that sets constant voltage to 13.8V was turned on. So... RTFM.

What kind of PSU has switch for such a weird value?

It is Voltcraft 25A/15V psu. 13.8V is probably intended for automotive applications.

[CJay]

HP Laptops have a really annoying 'feature', I've seen it on a hand ful now (I've processed over 1000 in the last 12 months) where the machine refuses to turn on.

Press and hold the power button for 15 seconds, then release, then switch on as normal.

[Stavos122]

Blown fuse in an Omega Engineering meter https://www.omega.com/pptst/HH314A.html  Saved a couple hundred.

[EE-digger]

Brought a half brain-dead, new to me 33120A Arb to life by momentarily shorting the PONRST line to +5V a few times with a scope probe.  I think this opened up a bad cap.  Details in the old 33120A thread.

[peteb2]

How's about a piece of Hi-End audio production suite monitoring-mixing bridge technology that enables the operator to verify audio levels across multiple stereo (on a group of LED dot bar 'VU' meters) embedded tracks and and to even decode the 'stream' to inbuilt speakers or use headphones.

The user called said the audio sound had stopped and it had been flaky for a few days. The had a something else installed, temporarily  but it wasn't  as good and were desperate for this one to be looked at. It arrived with user and the brief was that it had been a bit scratchy recently, a month ago but now it was dead but the VUs still worked fine.

So i looked at the front of the thing having never really seen one before and right beside the centrally marked VOLUME knob in a sea of push buttons and silk-screened labels was a jack socket labeled (headphone Logo)/MUTE... That's when i did a double take on the 1/4" socket and pulled out the 1/8"(3mm) headphone adapter that whomever was the last operator using Cans had left behind....

YEAH..... and you should have seen the look of the individual who'd spent the better part of a morning uninstalling, reinstalling and traveling on a mission of urgency....

I wonder too, how often do headphone 6.35mm to 3mm adapters cause mistakes like this?

[station240]

Visiting my friend many years ago, they had a massive CRT TV, like 80cm size, that didn't work anymore.
Everyone was watching it when it stopped working with a loud bang and sparks coming out the back.

They wanted it gone, so I took it home opened it up. No signs of problems around the mains section, however the module with the EHT was another story.
Undid a couple of screws to pull it out, flipped it over the see the back. Not only is there a EHT cable to the tube, but a secondary one runs into a finger sized 10meg ohm resistor, with a huge crack up the side.

The fix, pull the rubber boot back, unscrew the screw inside the port securing it, chop the EHT cable off the dead resistor, refit boot minus cable.
Voila set works again, resistor was only to discharge the tube when the set was off.

[iaso]

I had a 2010 Macbook Air. It had some screen issues. Apple quoted some ridiculous ammount for a fix. I opted out of that scam and basically decided to just buy a non-apple product.

On the way home I accidently dropped it.

It fixed the screen issues, worked fine for 4 years after that.

[rrinker]

For the computer builders here: did you ever have the experience that your friend's computer went dead, they couldn't fix it, and the computer magically fixes itself after you show up?

 All the time. It's my regular job to fix computer systems, more server side stuff, we rarely do deskside support any more, but even there, the same thing happens. Just called a client yesterday, he goes to demonstrate the issue he is experiencing - and everything works perfectly as it should, no errors.

 When it happens with a friend or coworker, I jsut say that the computer is smarter than they think and is afraid that I will resort to percussive maintenance. 

[jmelson]

OK, here's a funny one.  I have a home environmental monitoring system, that is cobbled together with all sorts of adapters, interfaces, etc. to a rack-mount  1976-vintage analog-digital converter.  It all works, mostly, but now needs a fan on it in the summer or you get wildly fluctuating readings.  (It measures outdoor and indoor temperature and humidity, electrical power consumption, furnace activity, etc.)  Well, a while ago it started acting flaky again.  I shut it down and pulled and reseated all the cards, cables, etc. and it still seemed to be malfunctioning.  The outdoor temps seemed too low.  After fretting with it for quite a while, I finally looked up the weather online.  Yes, a front had come through, and it really WAS 3C outdoors!  I think a connector was making a bad contact, and reseating fixed that, but then I didn't believe the readings, and spend another hour fooling with it when it was NOW working properly!

Jon

[rhb]

I got a wonky eBay 34401A.  Connected to a 5.0 VDC reference it just showed random digits on the mVDC range.

Opened it up and took off the internal shield.  I found flux painted all over one of the LF357s in a 1 cm spot.  I cleaned it off with isopropyl alcohol and a soft brush.  It now reads to the accuracy of a DMMCheck Plus which was calibrated to 1 ppm a few weeks ago.

The flux was so thick I couldn't read the chip markings. On close examination after cleaning the part was a different make and not quite aligned straight.  It had been repaired by a slob.

Rosin is hygroscopic.  In a humid environment this creates stray capacitance and resistances that play hell with low level signals.  Wash it off!

I've made similar repairs to a variety of consumer electronics devices.  The hardest part is taking the stuff apart to clean it.

[innkeeper]

Saw this topic and had to post cause it reminded me of one of the first repairs I did for someone else other than me and one of the easiest

this goes back some 35+ years ago....my brother was wanting a stereo system, but, was strapped for cash.  I brought him to a Macy's discount center where the would blow out returns and broken times, and sell off old models. There we found a complete Technics's component stereo system, with turntable, speakers, and cabinet....but one channel was out.

When I moved the speaker and I could hear a loose wire moving inside. the sales guy was hovering over us, so all i could really tell my brother was to buy it I can fix it. My brother paid very little for the setup... and we loaded it into the car, .. my brother being skeptical he was already regretting the purchase, until we got home, hooked it up, I unscrewed the woofer and reconnected the loose wire to the terminal and watched his amazed face.

I can remember feeling good about being a hero to my little brother...35 years later, he still has the system.

[CoopedUp]

 I got a nice hd 27" monitor from a business because they said it was faulty... When I got home I plugged it in to see what the problem was, and everything was green so I figured I would try the color settings and sure enough it got switched to the all green mode and I put it in rgb and boom free monitor.

[vk6zgo]

I think I've mentioned this one before, but here goes:-

An Icom IC 910 transceiver made "clicking" noises, & after a short time would overheat & drop in output power.
A misplaced ribbon cable was preventing the fan turning.
Redressed the cable, & all OK.

[digsys]

My last "easiest repair" was several weeks ago. I was called out to a intermittently operating plastics injection machine. I was warned that several service /
 techs had already had a look at it, and failed to find the fault. I asked for pix of the electronics to be sent, to get an idea of what I was up against.
It was a mess. A very old machine, heaps of PCBs, relays, connections, wiring etc etc. So I grabbed everything and went down.
Unloaded my car, oscilloscopes, DVMs, current sensors, heaps of parts drawers plus my trusty E8 errr I mean E4 FLIR.
Set it all up, opened the main cabinet door, whipped out the FLIR, had a quick scan ... and right there, in the middle of a huge row of terminals, saw one was
extremely hot !! Had a look - the screw was completely loose, and the eyelets were just flapping inside. Totally impossible to see with a naked eye.
I tightened the screw, and BINGO, all fixed.
Worst was reloading all the damn stuff back in the car, and putting it all back at the office.

[vk6zgo]

A mate of mine was asked by his Boss to produce a counter which would give a tally of how many times a
particular operation occurred.

It didn't have to interface with anything, so he grabbed a cheap pocket calculator, set it to increment the
reading by 1 every time the "+" button was pushed.

He then found a spot for a micro switch, wired it across the "+" button & it was done!

No microprocessor &  peripherals, just a switch & an "El Cheapo" chain store calculator.
(No PICs or Arduinos back then!)

[Rerouter]

vk6zgo, you can get little self powered increment / decrement counters with an LCD for dirt cheap if you know where to look,

e.g. https://www.fargocontrols.com/spcounter.html

Thoughts for next time, I have a few of these I have kept on hand, the battery has only discharged about 30% over 4 years of use, and they never turn there screen off.

[kripton2035]

non working inverter came into the shop. dead on arrival. called the manufacturer that managed a replacement.
then they left it "to disposal according to your country laws" ... so I opened it. battery was not plugged in ...

[vk6zgo]

 

vk6zgo, you can get little self powered increment / decrement counters with an LCD for dirt cheap if you know where to look,

Indeed, but this was 40 years ago!(Note the last sentence of my posting.)

e.g. https://www.fargocontrols.com/spcounter.html

Thoughts for next time, I have a few of these I have kept on hand, the battery has only discharged about 30% over 4 years of use, and they never turn there screen off.

Still good to know, but these days, the Boss would be a "suit",who would want the counter to upload to "the Cloud"!

[vk6zgo]

non working inverter came into the shop. dead on arrival. called the manufacturer that managed a replacement.
then they left it "to disposal according to your country laws"... so I opened it. battery was not plugged in ...

Not quite on topic, but fits in well with your story.

Back in the '60s, a lot of farmers weren't on the grid &  had 32v DC power plants.
Nobody made TVs to work on that supply, so they bought electromechanical inverters which used a very much "scaled up" version of the "vibrator" supplies used in old style car radios.

A country customer came in, wanting to buy one while he was in Perth, but when the counter attendant went to grab one from the store,"the cupboard was bare".

The counter bloke's eyes fell upon the one on display.
Sure enough, the exact thing, & the box was even there.

The sale was made, the customer went away happy, all was flowers & unicorns, till the Boss noted the counter display unit wasn't there.

You guessed it!
The counter one was a dummy with no active guts, just a few weights to stop it being easily nudged off the counter.

Luckily the Boss knew the customer well, so could make a good guess where he would go next, & "headed him off" before he set off for home.
Meantime, us lesser mortals were sent on a hunt to find an inverter "by hook or by crook"!

From memory, one of the country branches had one, which was quickly shipped prepaid to the customer's business address.

[madao]

my most (& fresh) easiest repair is  turbo boost sensor from my nissan Skyline.   bad solder, required resoldering.   I needed more time for extending of him than soldering.

Other one easiest repair:  I picked up Tek  533A  Oscilloscope for friends. Seller  switched him on  and i play. Trigger doesn't working.
  I pull it out case and saw a tube with white hat.   Of coruse, it is in trigger-ciruit.  Put one new tube - > problem solved.

[LapTop006]

Probably not quite my easiest after all the "actually worked fine" and "flip the power/input switches correctly" ones, but one of the most satisfying was a Keysight N6700 power supply mainframe.

Bought as "powers up dead" for an extremely cheap price I confirmed that when it arrived, took it a little to bits, didn't find anything, reassembled, and it worked fine.

Despite being new enough to be Keysight branded the firmware is all-Agilent, all the way.

[bitseeker]

Bought as "powers up dead"

That's a new oxymoron.

[innkeeper]

Probably not quite my easiest after all the "actually worked fine" and "flip the power/input switches correctly" ones, but one of the most satisfying was a Keysight N6700 power supply mainframe.

I had a quite satisfying "actually worked fine" one that happened quite recently. ..

I picked up this Tektronix 576 curve tracer that originally it was listed along with with a Tektronix 2465B 400 mhz 4 channel scope, both showing no trace, and listed on ebay "for parts" no returns. I figured they would be fun projects, so I gave an offer on eBay that was accepted. 

I drove 2 hours into NJ to an electronics salvage warehouse to pick them up only to find out they "goofed" on the listing and the scope listed in the title and in pictures was a "mistake" ... grrr .. well it seemed they weren't about to let me walk out with both the scope and the curve tracer... at least not for the price I paid. they wanted like +400 for the scope.  I felt that was very sleazy.

They kept offering me to come to the back look at other things to buy while I was there, it felt a lot like a bait and switch thing.

I ended up negotiating and refund on the scope that was in the listing and walked out with the "non-functional" curve tracer .... at that moment, I felt like I had been dupped...but on the other hand, was not upset at the deal on the curve tracer as a project piece.
 
However ... Karma is a wonderful thing...

It turns out that the curve tracer works fine, they just had no clue how to use it ..... 

[widlokm]

Not mine repair, but I've red this story long time ago on some clocks forum. Not the easiest one also.

In the past companies used "time systems" with one big "master clock" and many "slaves" connected to it by wires and triggered every minute to advance. Company claim was that some part of the system losses a few minutes every Monday, Wednesday and Friday. Clock engineers narrowed the problem to a particular "impulse amplifier" (electro-mechanical, just switches and relays), check it, found some dirty contacts, concluded that the week days was just an coincidence, repaired and ... that NOT fixed the problem. Then they simply replace the whole amplifier module - still no luck. In the last attempt they decided to do 24h watch of the falling unit in shifts.
The problem was fixed the next day: a person who watched the unit at night noticed that a some point a cleaning lady came in to the room, unplugged the amplifier and plugged in hers vacuum cleaner. After a few minutes of work she took a vacuum cleaner, plug back the amplifier and left the room. Cleaning was done on Mondays, Wednesdays and Fridays :-).

[vk6zgo]

A new low!

One of the charger cradles for our Uniden cordless phone had "croaked".
We only had one functional cordless phone, which needed to be in one particular room, so we needed to take it to the base unit in another room to charge it overnight.(couldn't just swap phones for a charged one)

After bring out of action for some time, following a Total Knee Replacement, I finally ventured out into the "Ham shack"/Lab, grabbed the Fluke 77, & did the simple checks.
No output from the charger!

Looked in the "computer junk" for a compatible charger.

Bingo!
The "charger" from our previous ADSL box was compatible---- even the same centre pin on the barrel connector.

The cradle returned to service.

You couldn't get any easier than that!

[Smith]

I bought a like new 1/10 LRP S10 Blast RC car this weekend at a local thrift store for 7,50, including remote and a good battery pack . It was untested, propably because there was no charger.

Charged it up, it would steer hard left. Inverting the steering made it steer hard right. Turned out one wire from the steering pot from the remote was not soldered propperly, and had come loose. Easy fix.

[briandorey]

I was given a bang & olufsen amp for spares which I was told was completly dead and their technician couldnt fix it, turned out to be a 50p fuse !

[GreyWoolfe]

I was sent 3 document scanners that we use in the field as non working to see if I could do anything with.  The easy fix was a jammed light bar.  Moving it back and forth a couple of times made it work.  It took more time to remove the 3 screws, undo 2 connectors and remove one cable than it did to make it work.  The other 2, unfortunately, were FUBAR'd.  How they could be dropped hard enough to shear the 3 mounting posts for the drive motor and not leave a mark on the outer case is interesting. I will be keeping one as a parts carcass, it already gave up its ADF tray for my office scanner.

[Psi]

I bought a faulty argon ion laser with powersupply for $20 because i wanted the large toroidal transformer that came with it.

I get it home and figure i will just plug it in to the wall to see what happens.  Fans power on and tube glows but no laser light.
I tap the mirror at one end of the laser tube and i get a flash of 488nm light.

So i grab an insulated screwdriver and turn the back mirror X adjustment screw about 4 degrees to the left.

Wow! laser fixed.

Damn it, i can't really rip it apart now that it works. And I really wanted that transformer. 

[dom0]

Tektronix 2246 that didn't trigger properly. I kinda didn't need it, bought it more for completionist/collecting stuff reasons. And it indeed didn't trigger reliably. So I just stashed it in my storage a couple years ago. Thought two hours ago, "hmm, I didn't use that 224-something in years!".

Works flawlessly. Quite a nice scope, too. (I should probably open it up and check there aren't any obvious issues inside)

[bob91343]

I have several.  One was an Astron power supply that had no output and was given to me by a ham radio operator in hopes I could use it after repair.  It has three terminals on the rear, positive, negative, and ground.  He had connected the load from ground to positive and it was a floating output so of course zero volts.

Another was a printer that I got from Craigslist.  It kept giving a paper out error message.  I merely corrected the positioning of the paper guide and all worked well.

[bob91343]

I have two units, a Tektronix oscilloscope and an HP bench DMM that have had bad power switches.  The previous owner of the DMM had bypassed the switch so he then had to use the power cord or a power strip as a switch.  The oscilloscope was a freebie at a swap meet; the power switch is buried so deeply I see why he didn't replace it.

In both cases I just exercised the switches and after a few times they became reliable.  Haven't had a problem since.

In another situation on a first date I was asked to wait until she finished getting ready.  The stereo was too loud so I tried to turn it down and found it cut out.  So I exercised the slide control until it started to work properly.  When she came out I told her I turned the stereo down and she said oh it's broken you can't turn it down.  Then she moved the knob and said what did you do?  It's fixed!

[ArthurDent]

I bought a FEI-Zyfer 565 GPS time and frequency system that was dead on eBay. The seller plugged it in, turned it on and there was no display or beeps when the buttons were pressed. I had several older 365 that looked the same and figured I might be able to figure out how to upgrade mine to this much more desirable and newer model so it was worth chancing the $60-75 to buy it.

When I received it, it was dead as described, but when I continually pressed the contrast button (see photo) the display came to life. I could then go through the menu and turn on the beep function for key press. There was nothing wrong with it except it was set up wrong. The main board was identical to the 365 model I had so replacing the old small GPS receiver board and an eprom upgraded all my other 365 units.

[eevcandies]

In the mid 70's the first scientific calculators were at least $300, and being a school kid, no chance at all of having one.  I found one--a store had a defective one that was returned because it always gave wrong answers...So I was able to buy it for $20.  I thought it was very very cool to have, even if the calculations were wrong.   A few months later I was messing with it & noticed that when I took the log of 36 I got 6.  When I  took the square root of 90 I got 1.000,  The square of 100 was reported as 2.  I suddenly realized most of the function keytops had been scrambled around.  I opened the unit & figured out where the keys should go.  Soon thereafter I had a fully functioning calculator. 

[dzseki]

I bought a "dead" pulse generator once, it works perfectly since the first trial, they probably tried with a bad cable or mains outlet... does this count as a repair? 

[Berni]

I bought a "dead" pulse generator once, it works perfectly since the first trial, they probably tried with a bad cable or mains outlet... does this count as a repair? 

If you are talking about the old analog HP pulse generators such as the HP 8012 or HP 8082. I bought one of those and i thought it was not working because the power indicator never lit up. But then i noticed it was actually producing an output signal. Upon taking it apart i found that the power indicator is a small incandescent bulb and it just needed to be tightened slightly because it became loose in the socket.

[dzseki]

I bought a "dead" pulse generator once, it works perfectly since the first trial, they probably tried with a bad cable or mains outlet... does this count as a repair? 

If you are talking about the old analog HP pulse generators such as the HP 8012 or HP 8082. I bought one of those and i thought it was not working because the power indicator never lit up. But then i noticed it was actually producing an output signal. Upon taking it apart i found that the power indicator is a small incandescent bulb and it just needed to be tightened slightly because it became loose in the socket.

Nah, this was a hungarian made one, it has a power LED (which they reported as not coming alive), but it is indeed working eversince.

[grifftech]

arcade game had no sound output, I tried connecting amplifier to smartphone, still no sound, bring amp home and put jumpers on volume controll connector, amp works fine, connect speaker to game computer, sound comes out, reinstall amp, issue persists, install volume jumper, sound works, reconect volume controll connector and check volume knob, it is turned down all the way, adjust volume, problem solved.

cause: co worker got annoyed with the continuous music in attract mode, so I turned the demo music off

[EOC_Jason]

I once bought a non-functioning symmetricom syncserver ridiculously cheap off ebay. This was a first-gen model that was a 1U rackmount PC, physical hard drive, tons of fans, etc. But it had an X72 rubidium module, which the price alone that I bought it for was worth that, along with the pci timing card.

What was wrong with it? Dead CMOS battery.... lol.  Replaced battery, reconfigured BIOS... worked like a charm.

[bitseeker]

This thread is wonderful for honing one's troubleshooting "common sense" across many product categories.

[Housedad]

Had a 12inch disk sander that stopped working.  4 screws to put a brush wire back the connector.  But the easiest thing ever only somewhat electrical related was my neighbors old dodge truck   He told me it had been running bad for a while and two shops quoted $500 to 1200 to fix.  I said let's look at it now. I had him start it and put my hand on the hood, for a minute or so. 

Had him shut it off, said cylinders 6 and 8 weren't firing.  Opened the hood, found the connectors were off of the #6 and 8  cylinder injectors. Put them back an it started running great and smooth.  He thinks I'm some kind of car God now.

[bitseeker]

Car whisperer.

[Housedad]

Car whisperer.

Not really.  Just an old skill my father taught me as a boy in the late 60's.  To concentrate and feel the pattern of the vibrations. I spent a hell of a lot of time after that practicing.

[tkamiya]

Mine was an Ebay purchase of Kenwood TS820, a ham radio equipment.  Since it was from 80s, it's a solid state and tube final (hybrid).  This type of equipment always had a switch on back labeled SG.  It means Screen Grid.  Turn it off and there is no RF output.  It was mainly there to disable the final so a transverter can be used.

Bought this radio with a comment "Receiver works, transmitter no output."  While I was cleaning, l looked at the back.  Aha. SG is off.  Flip the switch and everything works.  I have seen several like this since then.

Funny thing is, I let the seller know of my finding.  He yelled at me saying his technician of 40 year experience knows what he is doing.  No good deed goes unpunished I guess. 

[bob91343]

I had the same issue.  I repair ham gear for friends and this is very common, the neutralizing switch shutting down the 6146 screens.

[iroc86]

I picked up an HP 6236B triple output bench supply a while back that was listed as "parts only" and had the power cord cut off. It was in really good cosmetic condition, so I bought it mainly to refurbish another functional but not-so-pretty supply that I had. For kicks, I installed a new power cord just to see why it failed, and, you guessed it... no issues whatsoever. It passed all of the output tests, ripple measurements, etc. I can only surmise that the former owner (company) cut off the power cord to avoid liability, even though the unit worked fine. Sadly, my employer also adheres to this practice... and we're not allowed to rummage through the garbage bins.

A close second place for me is an HP 8111A pulse/function generator that was also sold as a parts unit. This one powered up, but threw all sorts of weird error messages and blinky lights on the front panel. All it needed was a thorough switch cleaning and it works great now!

[bitseeker]

I picked up an old HP 3312A function generator. Its output was all wonky. Solution was also to clean the switches.

[ChristofferB]

Got a neat 80's Yamaha drum machine (RX7) for next to nothing, because on power up, the LCD just displayed full block characters.

First thought was that the processor didn't boot since it looked un-initialized, which would be a bummer. Turned out the coin cell battery had died, and it was as new after swapping that. Don't know why that would make the CPU not run, but maybe it had shorted out.

I almost felt cheated that I didn't get to poke around and troubleshoot in the 8-bit digital hardware 

[CJay]

Got a neat 80's Yamaha drum machine (RX7) for next to nothing, because on power up, the LCD just displayed full block characters.

First thought was that the processor didn't boot since it looked un-initialized, which would be a bummer. Turned out the coin cell battery had died, and it was as new after swapping that. Don't know why that would make the CPU not run, but maybe it had shorted out.

I almost felt cheated that I didn't get to poke around and troubleshoot in the 8-bit digital hardware 

Used to be a thing with Compaq laptops too, I bought a few at auction in the early 90s which were 'faulty' but just needed a coin cell.

[Howardlong]

MSO8104A - front panel stopped working during an initial check out.

Was about to go full metal jacket on it, taking it apaaaart, but it turned out two of the rubber buttons had become stuck on due to the printed front panel legend being slightly mis-aligned.

Second time I’ve been caught out with this on a scope, the one before was on a Tek 2465B... some years ago.

[bitseeker]

Good tip. Thanks, Howard.

[ArthurDent]

I thought I'd mentioned this before but not here, I guess. Recently I bought a GW Instek PSM-2010 programmable power supply on eBay that normally sells new for about $1000 for well under $100 because the seller said that the cooling fan speed was erratic, even with no load, and they weren't sure if there might be other problems as well. This supply has an intelligent fan control and was working normally. I took the gamble that this was the "problem" and lucked out.

[bitseeker]

Sounds vaguely familiar. That is by far the easiest repair, eh? Just change your understanding of the "problem."

[m3vuv]

until you loose oil presure and screw the big ends!

[LazyJack]

Very easy repair. HP 3325A synthesizer, originally bought for parts to fix an other one. It was advertised as not powering up and the seller accepted a very low offer. Well, it is powering up, and works flawlessly. No repair needed.

A tiny bit harder repair: HP8904A synthesizer with a somewhat rare 600 ohm option. Also advertised as not powering up, however i spotted that it was set to 230V (US seller!) and missing the fuse holder. Well, took a chance again with an embarrassingly low offer and got it. Replaced the fuse holder, plugged into 230V (as I'm in Europe). Lo and behold, it works.

[DaJMasta]

I think I just had mine....

Got an SRS SR830 DSP Lock In Amp that was in good physical condition but wouldn't power up.  Arrived, looked decent, had something rattling around in it and a screw that was falling out the back...

So I opened the top cover, pulled out the nut, replaced the screw, looked for loose connections, checked the fuse - the usual - then plugged it in and flipped the switch in the rear.  Nothing, ok, well I looked on the front panel and eventually determined there was no power button.... which was odd.  Left the power on, got out the thermal camera, basically no heat generation anywhere in the power supply - was the switch disconnected?  Maybe something with the transformer windings?

But I was curious if there was some power button I was missing, so I opened up the user manual.  First thing it says, switch on the power and hold down the Display key to run the self tests and reset defaults... no reaction on first power on, but I gave it a shot... and it booted up, passed all self tests, and seems to be fine.


My guess is a power failure or the loose bolt caused an issue that needed to reset corrupted power-on defaults.  Since the power on sequence didn't seem to do anything, the seller just figured it was dead and didn't want to deal with troubleshooting the failure.

Turned out to be a great use of a half an hour! 

[Kilrah]

New one, family member had a 3 year old hp x360 laptop that failed, powered up less and less frequently until not at all. Obviously they call when nothing works anymore and not before. Took it home, opened it and had a quick look, no obvious liquid damage or burn marks etc, no schematic to be found online so since they were in a hurry to get the data and a working machine I took the SSD out, dumped the user data to an USB drive, took an unused working laptop I had in a pile and gave them that as a replacement. Kept the old one for parts, reused the SSD somewhere else and put the wifi adapter in the parts bin.
A few months later I again come across the machine I hadn't thrown away yet, and before doing so decide to have another look just in case since I had wanted to try one of those x360 things for a while. Took motherboard out again, removed all the shields, and upon close inspection a cap looks somewhat dodgy close to the RAM chips. Yanked it off and what do you know, it powers up great now! Threw a spare small drive in to test for a while and no more issue. So I bought a new decently sized SSD for it, and also ordered a new screen (touch panel was cracked as well). Replaced that and I now have a rather nice laptop with a 4K screen, although a bit underpowered and too big. Still a better way than buying a $2k laptop to "try to see if I like it". Confirms I'd really go for a 13" instead of 15 and definitely go for the best available CPU though.

[fourfathom]

Perhaps not my easiest, but my favorite:

This was back in the days of vacuum tube TV sets, and ours had lost the vertical sync.  I unscrewed the back cover panel and looked at the tube chart (no schematic).  I then slowly waved my hand over the components around the sync-circuit tube and got a feeling:  That semiconductor diode *right* *there* was bad.  I just knew it.  So I clipped it out.  It was open.  I pulled some unknown signal diode from an old computer circuit board I had in my junk box (a two-input transistor-logic nand gate as I recall), and soldered it in.  I didn't even know what polarity it needed to be so I guessed.

That fixed it!

And that's how my reputation as being able to fix anything started.

[Qmavam]

Back in the 80s I repaired VCRs, when they were still expensive.
 Fisher had a separate tuner module, when it went bad, you replaced it.
 No schematic, it was a module to replace at near $100 cost. After a few
repairs or declines I decided to see if there was anything I could find that could
be the problem.
  I started with the freeze spray, bam! the picture appeared. Hmm, so I
warmed it up until the picture disappeared and then dripped the coolant on individual parts
until the picture disappeared.  I found a 1uf 16V cap that was the defect.
From then on, it was easy, bad tuner, I'd let a drop or two of the colant hit that cap, picture would appear
I'd replace that cap, it always worked.
 Funny thing about VCRs, when a machine came in with a stuck tape (porn)
they never ask the receptionist to get it back :-0
 I can't think of any others right off,  but I did VCR repair for 10 years, over 11,000
repairs. It became so easy because I saw the same problem over and over. I was at a good shop
with loads of service literature and a good stock of parts. I ordered my own stock.
The owner worked with three big box stores that sent us their store stock (returns) that needed repair
and all of the store extended warranty repairs. (their money maker was the extended warranty)
 A sad thing I saw several times were rent to own units, a $220 VCR that was paid for biweekly,
when they finally had it paid off the cost was $1,100.
 That's brain dead with no financial self control. Oh that's another topic.
                                      Mikek
 I did only VCRs, and everyone else had a different specialty. So, if I had a dog, it was on me to fix it.

[MapleLeaf]

Looked in electronics recycling bin at work. Asus pad was in it. I thought good teardown. For fun i tried to charge it, nothing. Read on web that these pads can lock up. If you do a three finger hard reset they will come alive. So I tried it and came alive. Pad came up like it was it's first time from factory. Nice.

[themadhippy]

bss di boxes,had a couple that didnt work. Checked them with phantom power , ,nothing,try a battery ,it works,back on phantom power and  it still works,look at the next one ha ha , battery connector was shorting out to the circuit board,bit of tape over the battery clip ,job done

[pcmad]

this week end i got a table saw that didnt power up turns out the brushes had a bit of saw dust jamming them pulled the out a put them back and powed up

[Howardlong]

Another nice easy one, I use an Agilent 8935 Communications Test Set as part of a production test jig, they're old, circa 2000. They work well, are usually reliable, and are cheap on the second hand market. They're also built like tanks.

Today I came to use it, switched it on with the rocker switch, but nothing happened, no life at all. I checked the fuse and integrated GFI, all good, and power was getting in somewhere as the GFI trip test worked when plugged in.

Problem with these units is that there are tons of screws to facilitate disassembly, but thankfully they're almost all the same T20 screw.

The internal standby LED was working but no other supplies.

It turns out it was the rocker switch, rated at 10A 250V, but judging from the wires on the short cable harness this is a low voltage, low current soft connection. Sure enough it was the switch, I could switch on the unit by shorting the connections.

Expecting to need to order a new one, I had a look in the switch drawer and amazingly I actually had a small stock of fit-ready replacements, albeit black rather than white.

[Cubdriver]

Another nice easy one, I use an Agilent 8935 Communications Test Set as part of a production test jig, they're old, circa 2000. They work well, are usually reliable, and are cheap on the second hand market. They're also built like tanks.

Today I came to use it, switched it on with the rocker switch, but nothing happened, no life at all. I checked the fuse and integrated GFI, all good, and power was getting in somewhere as the GFI trip test worked when plugged in.

Problem with these units is that there are tons of screws to facilitate disassembly, but thankfully they're almost all the same T20 screw.

The internal standby LED was working but no other supplies.

It turns out it was the rocker switch, rated at 10A 250V, but judging from the wires on the short cable harness this is a low voltage, low current soft connection. Sure enough it was the switch, I could switch on the unit by shorting the connections.

Expecting to need to order a new one, I had a look in the switch drawer and amazingly I actually had a small stock of fit-ready replacements, albeit black rather than white.

 

-Pat

[jogri]

The easiest repair? I found a nice four channel 150 Mhz scope that wouldn't power on in the bin. Looked for the fuse, found a burnt one. Luckily it had one of those fuse holders that have a spare fuse (which was still good), changed the fuse and got a fully working scope. Not a bad price for two minutes of work.

[mikeinkcmo]

Many years ago I bought a Tek 454 scope off ebay that didn't work.   I closely examined the pics, I was convinced there was most likely a problem with one side of the Vertical amplifier, Its a balanced type circuit.   

Got it, opened it up, the wire connecting the top vertical plate to the amp had fallen off.   THAT WAS IT, re-attached, and been working perfectly ever since.

[bd139]

Nice looking shelf of kit that 

Quick one the other day. Someone had been "at" an HP 3466A I got on eBay. Before and after fix.

Before repair



After repair



Looks like someone had replaced the RMS converter IC and put the new one in back to front. This caused the -7V rail to conduct to ground and the whole thing to go wonky. I'll admit it took me a good 30 minutes to work out this was what was wrong. Much 

[Falkra]

Nice. 

[Cubdriver]

Many years ago I bought a Tek 454 scope off ebay that didn't work.   I closely examined the pics, I was convinced there was most likely a problem with one side of the Vertical amplifier, Its a balanced type circuit.   

Got it, opened it up, the wire connecting the top vertical plate to the amp had fallen off.   THAT WAS IT, re-attached, and been working perfectly ever since.

I recognize that screen name!  Welcome aboard, Mike, and definitely come join us in the TEA thread.

-Pat

[don.r]

Bought a Keithley 197 off eBay recently for less than $40 as a Parts unit. It was displaying "Err". Looked at the pictures of the sale and noticed the issue so I bought it. This model displays Err when the AC switch is selected with either the Ohms switch or no other mode switch selected. It works fine with any proper mode selected.

[Neomys Sapiens]

Bought a Keithley 197 off eBay recently for less than $40 as a Parts unit. It was displaying "Err". Looked at the pictures of the sale and noticed the issue so I bought it. This model displays Err when the AC switch is selected with either the Ohms switch or no other mode switch selected. It works fine with any proper mode selected.

Good to know. I'm watching one.

[fixy88]

Bought an Olympus OM-D M10 with a stuck shutter recently. Opened it, reseated the shutter block flex cable and it's been working great since. Win!

[kaz911]

Not the easiest but close

2 power modules for my Agilent N6705B - bought as a for parts set.So I bought both for $150,- - and they cost a bundle as working. (It is the high precision ones) - in working condition they would have cost $1500+ each.

The power modules have parts of the circuit exposed at the bottom where it connects inside the N6705B.

Got them - and put them under the magnifying glass - and found both had been bashed so one of the big diodes on both had been knocked slightly off the board. I de-soldered both and soldered them back on - and voila - both was working again. Time taken - less than 35 minutes from delivery...

I learned there and then that out of the N6705 - one have to be careful with the power modules. Always leave the circuit board part upwards and protect it when not in the N6705.

But all of my 6705 modules have been bought as broken and fixed. But this repair was the easiest.

/k

[wn1fju]

Seller said that the "power" meter didn't move and therefore also concluded (wrongly) that there was no output.  Well, yeah, if you leave the meter
switch on mA dummy!

Worked perfectly right out of the box.  Not bad for >50 years old.

[nfmax]

Agilent 33120A function generator, about to be thrown out, acquired it for free. A big label on it, saying 'no output at all'. Indeed there wasn't. The soldered-in fuse on the attenuator output was blown. Hardest part was working out the current Litelfuse equivalent part number.

[aeberbach]

Motor start capacitor, clothes dryer. I can't drive by clothes dryers waiting for recycling collection any more without checking them out to see if they are better than the one I have, because they probably just need a $5 capacitor 

[twospoons]

I had a 22GHz TEK492 RF spectrum analyzer with a dud 30dB attentuator step. After dismantling the attenuator assembly I took the tiny 1cm square of glass belonging to the 30dB step and checked under a microscope. A tiny dot of conductive silver paint over the burnt out thin film resistor (first in a chain of 8 T sections) was all it took to get it working again. Incredibly the 30dB step was still so close to being 30dB I couldn't tell the difference.
OK, so maybe its more complex than " I changed the fuse", but it was way easier than I was expecting.

[0culus]

Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well. 

[Neomys Sapiens]

Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well. 

Yep, nice one. But the moment it started ticking must have been nervewrecking.

[dzseki]

Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well. 

Yep, nice one. But the moment it started ticking must have been nervewrecking.

For $125 I would not have expected otherwise

[JohnPen]

A B&W TV had a sizzling noise and a slightly ragged picture.  With the rear cover off and in a dimly lit room observed a small blue arc into space.  On closer inspection found to be a poor joint in the EHT department with a long solder whisker on the joint.  A quick application of physics and a nail file rounding off the joint and all well again. Yes I did power it down first.

[0culus]

Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well. 

Yep, nice one. But the moment it started ticking must have been nervewrecking.

Yeah, especially since it was working fine when I tried it out at the auction preview day. 

Tektronix 7104. Bought the whole thing at an auction (including plugins) for $125. Got it home and suddenly it was ticking....after much troubleshooting it turned out to be the resistor that screws to the rear of the chassis...it got loose and was shorting the fan circuit to ground. Tightened it and all is well. 

Yep, nice one. But the moment it started ticking must have been nervewrecking.

For $125 I would not have expected otherwise

It was working fine on auction preview day.  I suspect the resistor was already loosening and act of carrying it out of the warehouse and the ride home perhaps shook it all the way loose. The whole thing is in great shape, obviously lived in a lab where the test equipment was taken care of. Microchannel plate crt is good working order.

[HackedFridgeMagnet]

Just got a call to fix 5 broken PCs after test and tagging, this was in front of about 30 people.

Waved my magic wand (voltstick) and saw there was no incoming power. The cords looked plugged in but were not fully inserted.
That took one minute and there were a lot of red faces. 

[NiHaoMike]

A B&W TV had a sizzling noise and a slightly ragged picture.  With the rear cover off and in a dimly lit room observed a small blue arc into space.  On closer inspection found to be a poor joint in the EHT department with a long solder whisker on the joint.  A quick application of physics and a nail file rounding off the joint and all well again. Yes I did power it down first.

I wonder if it has been previously repaired with lead free solder, since monochrome TVs long predate RoHS and leaded solder should be immune to developing whiskers.

[helius]

It may have more to do with the joint quality. A cold joint that spikes up has a greater tendency to arc. Using a firestick with no flux is guaranteed to make those types of joints, even with 63/37.

[pcmad]

Just got a call to fix 5 broken PCs after test and tagging, this was in front of about 30 people.

Waved my magic wand (voltstick) and saw there was no incoming power. The cords looked plugged in but were not fully inserted.
That took one ute and there were a lot of red faces. 

i work in it and so many times i had poeple vontact me  say pc not on my frist question have you made sure it pluged in

[george.b]

A B&W TV had a sizzling noise and a slightly ragged picture.  With the rear cover off and in a dimly lit room observed a small blue arc into space.  On closer inspection found to be a poor joint in the EHT department with a long solder whisker on the joint.  A quick application of physics and a nail file rounding off the joint and all well again. Yes I did power it down first.

I had a HP 700/96 serial terminal that was making an audible HV noise. Nothing noticeable on the image, though. I took it apart, washed the board with soapy water, let it dry for a few days, and that fixed the noise issue.

[Messtechniker]

Because a Windows 8 update was permanently stuck at 95% this Lenovo Z50 Notebook was replaced and about to be tossed. Managed to get my hands on it just in time.
The problem: BIOS was set to UEFI instead of legacy.  Simply changed that and Bingo!  It now has a SSD and a new life with Windows 10. After going though the usual Windows 10 motions of course to shut it up a bit.

[Ruediger]

My simplest "repair" was an oscilloscope (built in 1975) that was used in a university project. When I joined the project they said it had been broken for 2 years and I can have or scrap it. After cleaning and setting it from 110 to 230V I could use it without any problems.
 
Another simple repair was a broken solder joint in a 30 year old audio amplifier .