Chap blew up critical equipment on his first day – but it wasn't his volt The world is still turning, which sadly means another Monday has come around and many readers must resume the tedious business of exchanging their labor for currency – a tiresome necessity that The Register marks by each week offering up a new instalment of Who, Me? in which readers reveal errors they almost escaped. This week …
I once heard of someone who asked for a PC upgrade, was declined, and decided that changing the voltage selector from 240V to 110V for a while might help to "justify" the case.
Sure enough, there was a "crack", the thing went dead, the switch was returned to the 240V position and a call placed to the support team - who, after a bit of testing, diagnosed that the fuse next to voltage selector had failed, with "normal" service being restored soon after.
I had a router that was fine for 6 months then started randomly crashing / disconnecting. Of course it would take hours for it to happen and I could just see support people deciding it was fine, or some other problem.
So charged up a capacitor from the mains and applied it the the USB port and got a satisfying crack. Now I had a dead router which was much easier to get replaced. Dishonest I suppose, but the router was already faulty, I just made it definitive.
A user decided to set a BIOS password on their (company) laptop, which, of course, they had forgotten by the time they handed it in for a new one.
As it was still in warranty, the solution was to run the terminals of a 9V battery across the mainboard a couple of times until it wouldn't boot, then ring up the support line.
Thanks for sending out the replacement mainboard so quickly Dell ;)
We had similar issues back in the day with Seagate MFM drives. This was back when a 40Mb drive was considered big.
I ran the service department for a computer store. We would sell new systems with these Seagate drives in them, that would fail in about 3-6 months in the field, resulting in data loss of the customer. We would RMA these drives, and Seagate would just low-level format them, and send them back. They would do the same thing again in 3-6 months.
So at one point, I took a standard power cord, chopped off the end, and soldered on one of the old four-pin Molex connectors that were used for drive power before SATA became a thing. I kept this cable under lock and key, for obvious reasons. The procedure was to take the drive out, plug in the Molex connector, clear the area (parts would sometimes fly off of the board), and plug the other end into an outlet. We sure didn't get those drives back reformatted. We were just getting someone else's re-formatted RMA, I suppose.
I won't buy Seagate to this day...
The computer store I worked at during the 1980s sold a lot systems with ST-225, ST-238R, ST-251, and ST-251R drives in them, but got few returns. However, we had a rigorous setup/testing procedure:
1. Fetch a new drive from the unheated warehouse into the heated work room. 2. Connect to the computer. 3. Power up the computer. 4. Run the computer, doing nothing, for 45 minutes so the drive would warm up to its normal operating temperature. 5. Low-level format the drive via the controller card's BIOS, guessing at the best sector interleave and track skew values. 6. Use CORETEST to determine the transfer rate. 7. Re-LLF the drive with our next guess at interleave and skew values. 8. Re-test with CORETEST to see whether the effective transfer speed went up or down, and choose new values of interleave and skew accordingly. Go to step 7 until we determined the best transfer times, and associated interleave and skew values. 9. If needed, re-LLF the drive using the best sector and interleave values. 10. Go into the disk controller's BIOS and enter the manufacturer's defect list. 11. Test the entire drive for bad sectors using some program whose name I don't recall. 12. Enter the bad sectors found by the testing program into the drive's defect list (via the disk controller's BIOS). 13. High-level format the drive via MS-DOS (checking for bad sectors). 14. Install full MS-DOS and the store's standard software packages.
You missed a step. If the drive is really cold, depending on the local climate/weather, leave the drive in the heated workshop for an hour or so to acclimate to the local temperature and allow any condensation to evaporate off that may have accumulated on a cold metal brick brought into a warmer location. Only then apply power to the device.
When I used to fix computers for a certain fruity vendor, I brought in my Tesla coil from home to invisibly kill any parts that had an intermittent failure, to ensure it was permanent, ensuring we never got the faulty part back after they "tested" it. No visible evidence, and did the trick.
Ah yes, the "send it in with a detailed fault description, get it back as NFF".
Maaany years ago, we bought an A3 printer - this was when there were (IIRC) only 3 models on the market that we found, and the price tag was something like £13k in 1990s money. It developed a fault in the serial port we used - one of the hardware handshake lines wasn't working.
Sent it in with a detailed description of the fault, get it back a couple of weeks later as "NFF" - and the serial port reconfigured to software (Xon/Xoff) handshaking. The (expletive redacted) idiots had simply reconfigured it to the settings on their test PC, ignored the fault description, and of course found no fault as they had configured it to not use the faulty mode. We weren't amused !
At the risk of showing my real age, that was a minor part of a plot line from Blake's 7. There was a fault in a large circuit board, and the ships automatic repair systems hadn't got round to fixing it - not high enough priority. So one of the characters connected it to the "mains" and it visibly shorted out all over. After a few seconds it started rejuvenating - the massive failure had elevated the repair in the priority list.
IEC leads are a worldwide standard, yet they carry at least two dangerously incompatible voltages. Maybe the world should have adopted different connectors for the two different voltages.
Incidentally, there are already two slightly different plugs and sockets for high and low current devices. You can't plug a printer lead into a kettle as it wouldn't take the current.
I can't help myself, I'm going to have to be the "well, actually" guy. Sorry!
Those differing connectors is actually a temperature thing not a current thing. The kettle connector has to be different (and has a little notch to enforce this) because the kettle gets hot and the connector could rise above 70 C.
i didn't realise this but there is also a "very hot" version if the temperature might go over 120 C.
But, yes, I do agree that the whole "could be 120V, could be 240V, who knows?" thing is strange...
Although, on the up side, an actual kettle lead will most certainly do as an emergency replacement in a pinch for a PC or printer. Obviously not the other way around though because of the notch. And assuming in the successful case that the piddly little short kettle lead is long enough for the application.
On the other hand, you may upset the local tea drinkers, so only attempt at your own risk!
You can't plug a printer lead into a kettle
We had a kettle at work that *didn't* have the extra notch in the power lead, and yes, someone replaced the original with a computer lead.
I don't know how long it lasted but eventually the lead decided it had had enough and started emitting smoke and flames. Fortunately I was in the kitchen at the time and knew the standard procedure in such cases* - turn the thing off at the wall! No drama in the end, it fizzled out and a new, hot condition, lead was easily procured.
*I did hear the tale of a generator fire, after several extinguishers had been tried and the fire was still going someone had the bright idea to stop the generator!
I shocked (figuratively) some of my data center coworkers by specifying 208V for a server project we were doing. The Dell power supplies took it with no complaints.
It said 90 - 264 VAC and they weren't kidding. My boss had also specified four fully loaded, fully redundant Dell blade enclosures. So I needed 6 outlets per enclosure, times four enclosures. The electrical engineer's eyes got wide and he explained that I would end up having something like a 1/3 of the entire data center's electrical capacity. We wanted to grab it while we still could. So under the raised floor went 6x208V 50A 3-phase outlets and associated 0U-space full-height PDUs, four per rack, times two racks, split between not only multiple breakers, but multiple breaker boxes as well. Then they decided to chuck the blade enclosure idea, so we didn't need all of the outlets anyway, but they are almost certainly still there. This was a time when core counts were rising precipitously, and SSDs were just starting to greatly increase database performance. We went with a whole stack of Dell two-processor 1U servers, and an external drive enclosure. Interestingly I burned the servers in by mining Bitcoins at a time when Bitcoins were practically worthless and easy to mine. I deleted perhaps 10,000 of them because I didn't think they would ever be worth saving. Boy how I wish I had seen that coming!
I did that without breaking anything, back when VGA was a New Thing. Unlike the DE9 which preceded it, the 3-row pin configuration of the HD-15 VGA connector is perfectly symmetrical. I was able to mate it the wrong way around. The outer shell of the male connector was flexible enough that it didn't present an obstacle; it just re-formed the D in the opposite direction to conform to the socket I pushed it onto. When I phoned support to report a DOA monitor, they knew to tell me to flip it over the right way. So, in my defense, I wasn't the first to have made the same error.
That's why those baby toys with the shaped blocks and holes as so important.
You can watch everyone else's kid trying the block in different holes as they learn
Then you can watch your kid furiously hammering the square block into the round hole - and know you have bred a future engineer
I agree that we should. It won't happen though.
I was yesterday looking at the cost for wire alone for a new workshop building I intend to start construction on next spring. The cost of the wire alone is more than the price of the lumber to build the building. I'm looking at $3000-$4000 in just wire. If it weren't for our stupid 110V grid, the wire cost would be much lower.
The price of wire is absolutely nuts right now! Not that long ago I could buy a 250 foot roll of 12-2 for $28, now it's $165!!
Can I suggest you connect a whole bunch of the sockets in a ring rather than running individual lines ?
That way you have twice the current capacity and use much less copper
Or you could save up your KitKat wrappers and use those as an alternative to Cu for house wiring.
> ...new workshop ....$3000-$4000 in just wire. ....Not that long ago I could buy a 250 foot roll of 12-2 for $28, now it's $165!!
> Can I suggest you connect a whole bunch of the sockets in a ring rather than running individual lines? That way you have twice the current capacity and use much less copper
He's talking a MILE of wire!! (5,300 dead king's foots). This is no bicycle-fixing garden shed. This is more than my whole house! Modest, but an outlet every 10' or less (Code effectively suggests every 12').
Ring-mains are advantageous only for certain assumptions of loading and load-locations, and will normally force fused plugs. (You think this is normal but nobody outside the UK/BS world has fused plugs generally.) Historically they were one guy's idea, and in the crush of rebuilding post-war Britain he got his concept adopted.
There is no NEC requirement for home-runs on all outlets. General outlets can often run a dozen outlets per 20A circuit. I've had 44 (mostly quarter-Amp warts), though local inspectors frown.
We have 240V center-tapped. His heater and dryer can be run 240V. He can, within limits, run multiple 120V loads on a 3-wire 240/120 ("12-3") line (this is just unusual enough to now require ganged breakers).
He can run #6 or #2, 50A or 100A, throughout the building, and breaker boxes to divvy-up to 20A circuits.
At several $K he's in a gap. For $20K demand he could bring 440V into the building and put 440V:240V transformers near each corner. My old school was wired that way.
No, this is not going to be a "garden shed". We are talking a bunch of welding equipment, plasma cutters, CNC machines, etc. We don't have 3-phase available, so I will need to run phase converters for some of the machines.
Ironically, a lot of the building will be 220V outlets. Here in the US, 220V outlets are usually home-run.
The big cost is the wire from the main panel out to the new building. It's about a 200' run because I have to trench around other structures, and the wire is about $7.00 per foot these days.
Also, heat/AC for the building will be via mini-splits. So I have to account for that load also.
In the early days at college there was a planned power outage so we got a generator to run the studio. We then pulled the main breaker and made an extension cord with male plugs on both ends. one was plugged into the generator and the other into a convenient wall socket. Everything worked except the zip cord between the two plugs was quite warm to the touch. We had to be careful not to bunch up the zip cord to keep the temperature down. The generator was fueled with gasoline which we kept in glass jugs which we filled at the local gas station.
I'm glad OSHA wasn't around then.
Extra points: count the number of safety principles that were violated.
>North America & Japan must upgrade to 230V.
Japan yes, they can even keep their traditional power diversity by changing which pin is earth in different parts of the country.
But can Americans really be trusted with 230v ?
Have you seen how easily they hurt themselves with relatively safe toys like SUVs and AR15s
The joke is more and more North American homes have at least some 230v outlets because they have discovered that HVACs, water heaters and ovens work more efficiently at 230v. And yet they still stick with 120v for everything else even when 230v is the superior and more energy efficient voltage of the two.
(the 230v is actually two phase tho. Most North American homes receive two phase power totaling 230v two phase. But Electroboom has proven that it is possible to get the raw 230v power to work with European devices by jury-rigging an adapter that connects the live wire to one of the live phases and the neutral wire to the other live phase).
I actually built up some new customers who had problems with their new computers that weren't bought at my location. Guy brought in his computer saying it just wouldn't start up past the blinking cursor.
He had taken it back several times to the store he bought it at and they couldn't be any help since they were basically a department store who sold boxed computer sets as a sideline.
He set the computer down on my tech bench and i connected it up to my system. Turned it on, blinking cursor came up, turned off. Looked around the back, told him I can fix it.
Put both hands on the front and back, and in my best faith healer voice said "A-HEALLL". Turned computer back on, up came the POST screen and then the set up screen.
The guy was speechless. Asked how much he owed and I told him nothing. All I did was change the power switch from 220 to 115 when I was holding onto the computer.
Turns out, he was a local pastor and told his congregation he had met the best person to work on computers. Got a lot of customers from that.
Oh dear.....
The connector is rated for a maximum continuous current and a maximum voltage.
The cable should be rated for the fuse that is fitted, the temperature of the environment and the conditions of installation.
The fuse is rated to the device it is protecting.
Changing the fuse doesn't uprate the cable, but the cable might be over-rated.
Using the wrong cable is naughty and can have disastrous consequences.
There are regulations for this sort of thing. Boring, not easy to grasp but if followed, lead to safe connections.
I'm not one to laud Portable-Appliance Testing but you find a lot of stunning incompetence.
Not quite correct - yes, there are regulations, but no, the fuse is not rated to the appliance, it is rated for the cable - according to the regulations (I'm thinking in particular of BS 7671 in the UK, but most international regs use the same principles as ours do, for obvious reasons). Sometimes an electrical designer will specify a lower fuse for a circuit, but the cable (including adjustments for installation conditions) is the limiting factor, not the load.
This must be about 15-20 years ago, Compaq (remember them) produced a line of laptops with docking stations the size of full PCs (think 50cm square footprint), these the laptop was locked into, with an eject button on the case. The mechanism wasn't that reliable and there was a manual release lever under the back cover (which could be removed with the power on as the eject still needed mains). A user rang up and said they had a stuck laptop.
No problem - just pull the access cover off the back and flick the white lever over to release the locks, user did this and then when they flicked the lever there was a loud bang. On the back of the chassis was a 110/240V selector and the eject lever.
Don't need to say any more....
p.s. this was the same user who couldn't get a dial tone on a modem from his hotel room when he rang the office to complain and someone asked him how many phone lines where in the hotel room...
I was in a hotel in Japan, and could not get the "local dial in" to work. I dialed to the UK ( expensive) and reported it. Next day I got an email saying the number does work, I tried it - it didnt. This pingponged for a week, when I finally asked the technician what number he was using. It was a different number to mine. He tried the documented number- it didnt work because it had been misprinted.
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My late father retrained as a TV and radio repair technician when it was still CRT and valves.
The voltage on the frame flyback transformer could be up to 50kV and a current usually under 10A.
He was taught to work right handed and keep his left hand in your pocket, so any shock went up the right arm and down the right side of the body, bypassing the heart.
> the frame flyback transformer could be up to 50kV and a current usually under 10A.
That's a half a MegaWatt!!
No, the available current is closer to 10 _milliAmps_, and fading quickly when loaded. Not entirely benign but rarely fatal.
Part of the reason for getting HV DC off the horizontal ('frame') sweep is to use a small capacitor (the CRT's self-capacity) which will collapse quickly under the load of a body.
I've been bit by CRT power. When you realize what you did and are still alive it feels wonderful.
I've also been bit by half of 30KV AC limited to 30mA, a neon sign transformer. You sit down really hard and wait to see if you are gonna go or can stay. I stayed and stopped fooling with high voltage.
The various effects is why I always enforce a tea break on anybody who gets zapped. The enforced inactivity gives time to monitor for adverse effects and time for the shock (physical, psycological) to wear off, and the amount of time for a cuppa is a convenient rule of thumb.
And, yes, you do get bored out of your mind being forced to sit there drinking a cup of tea when you instinctively want to get back to work.
Didn't BOFH use varying levels of 'zzzt' to indicate voltage? Bzzt = warning shot, kzzt = temporary incapacitation and KZZZZT when you really mean it? Accordingly I would respectfully submit the following as Reg SI units for mains voltage;
zT = US 110v
bzT = Euro/World 230V
kzT = 3-phase
KzT = anything above 430v usually resulting in extreme crispiness.
《I suppose we should be grateful that the Americans use volts rather than an archaic system of measurement.》
I can offer to any L.Pondians who don't wish to sully themselves with the cheese eating etc SI units:
foot-pound per imperial standard charge - which presume one might define as the charge on two 1ft×1ft parallel square plates in vacuo separated by 1in which exerts 1lb force :)
If non north americans are curious about their 120V/240V system I found this video https://m.youtube.com/watch?v=jMmUoZh3Hq4 enlightening and in AU rather scary (when compared with AS/NZS 3000:2018 Amd 2:2021.)
> I suppose we should be grateful that the Americans use volts rather than an archaic system of measurement.
Be very, very thankful that they didn't decide to take the potential difference from one Voltaic cell (copper/brine/zinc) and just call *that* one Volt instead (it is about 0.76V, btw). In keeping with their habit of using units that _sound_ like proper Imperial Units but aren't quite...
In my very first job as a temp night fill worker at a department store at the grand old age of 15. I was asked to tidy up the Christmas section, in preparation for refilling. So I diligently started putting away things. Whilst cleaning up the aisle with boxes of Christmas cards (the 10 cards and envelopes in a box type), I noticed there was a huge pile stacked on top of the aisle. Finding one box of Christmas cards, that wouldnt fit in the actual shelves, I placed that one box on to the huge stack on top, at which point the top shelf for the entire aisle collapsed, sending thousands of packs of cards crashing to the ground, with an almighty ruckus that basically brought the couple dozen other shelf fillers in the store running for a look. I almost turned tail and fled!
I expected to be fired on the spot, but instead I was politely asked to tidy it all up (and try and put all the cards back into the appropriate boxes), and the stacker who had put all of these thousands of packs on top got a bollocking. My direct manager quietly congratulated me on saving the Store from potentially being sued by a customer, because if all of those boxes had come down on customers there would have been hell to pay...
Here in the States, odds are the engineers would have found some way to blame it all on the new hire assuming the boss even bothered to investigate that far. The corporate world here is all about playing hot potato when it comes to assigning blame and it's depressingly common for people to get fired from jobs for things that really weren't their fault... at least not exclusively.
Come to Japan where depending on where you live in the country you'll be supplied with power of a different frequency, Eastern Japan has one frequency and Western Japan has another, both are nominally 110 volts, plugs are the same for both areas. Whilst 90% of equipment doesn't really care and will work regardless the other 10% will have all kinds of issues from intermittent faults to releasing the magic smoke.
And sods law requires that the one item you really need to work is the one that'll crap it's guts out.
South Korea has (or at least had in the mid '90s) outlets there were 240v 60hz as well as one that were 110v 60hz.
This lead to an issue with some kit that had been sent out to animations houses as it had an analogue CCTV camera that used the frequency of the voltage for some sort of timing signal.
It took nearly a week of investigations before a replacement power supply came in for the digitiser that was marked for local use, then a dip switch change on the camera got them working for at least 2 different places that over there that purchased the system.
I got a week in Seoul (but only about a day to look around as it took that long to work out the issue).
I remember powering up a VFD on the shop floor when I saw a red LED light up. Hmmm...that had never happened before so I briefly leaned my head over to investigate. Not seeing the problem right away I turned to disconnect the power. Then I heard a huge bang and saw a cloud of smoke... right where my head had been seconds earlier.
Turned out that someone had re-stocked a 220V VFD in a box labeled 440V and... I hadn't bothered to look at the label on the VFD.
So... one of the 3 (big) capacitors blew when powered with 440.
Learned my lesson... now I check everything twice... before powering up.
The first time I plugged in a seven-segment display on a breadboard to test it I accidentally left out the common-cathode resistor. I powered on my bench power supply and had the time to think "hey, this one is yellow, I ordered an orang..." before it popped and didn't have very much of a colour at all after that...
There was a Gateway computers model that if you plugged the keyboard into the mouse socket and the mouse into the mouse socket. The onboard keyboard chip was permanently damaged. Who know having identical sockets for both would lead to such an accident.
Years ago, I recall hearing of someone deliberately zapping computer hardware that he had only a temporary need for and taking it back to the vendor for a refund.
On a slightly different note, I also recall being told that hooking a small signal germanium diode to the AC mains resulted in some interesting visual effects.
I did something similar with a manky old Oscilloscope years ago. Think it was a Hameg thing. It'd come back from site abroad where it was run on 120V and never returned to 240 back in our labs and when I plugged it in it went pop. I was never allowed to forget this but the bastard I worked for did the same thing about a year later. Obviously I couldn't say a thing but it became one of those elephants. Great fun..not.
Recieving a threatening letter from Virgin media demanding I return a rubbish TV box straight after I terminated my contract with them one that hadn't been replaced during three contract renewals left me truly fuming. I gave the insides a good shock and hammer treatment before returning it to those bastards.
A similar (Manufacturers) error (Mains colour coded cable used for a DC cable) cost me about £500 about 40 years ago. I ran an Acorn dealership and a customer brought us a BBC Micro for repair. The reported fault was a few dodgy keys on the keyboard. (The key switches are individually soldered in). My engineer though reported the computer as dead along with the Torch Z80 coprocessor that was inside. Investigations showed every chip we tested was dead. The customer was adamant that it was all working fine when he gave it to wife to drop into us and we must have blown it up. We replaced the motherboard & Z80 card (Nearly £1000 worth) and the customer reluctantly paid half the cost. About a month later his wife came popped in for a printer ribbon and told us the full story. On her way to bring us the computer she'd popped into a friends who's husband offered to fix the computer, he spotted that the power input lead was non standard so fitted a UK mains plug and tried the computer which showed no signs of life. Hence it was brought into us. The non standard power plug was part of a Torch Z80 co-processor & floppy drive disc pack. The PSU Acorn fitted to very early BBCs was linear and didn't output enough to support the Z80 Co-Pro so Torch supplied a PSU in their disk pack which had a three pin DC output. The DC plug looked like a three pin miniature round pin UK mains plug! It supplied the +5V and -5V that the BBCs motherboard used, that was bad enough but Torch used mains colour coded cable! Thus 240V AC was applied to the BBCs 5V rail!
The friends husband was partially to blame but I think Torch's choice of mains cable for a DC lead was the main culprit. The wife did say her husband hadn't spoken to her for several days after she mentioned about the friends husbands repair attempt. I should then have gone back and asked for full payment but I chickened out, we had after all supplied the Torch Z80 upgrade.
Unfortunately there are still no standards for DC cables. DC 2.1 & 2.5mm connectors are common but they are used for many voltages! Multiple voltage DC plugs are very rarely the same, even sometimes from the same manufacturer. Later USB C specs allow for a single voltage up to 48V but that requires intelligent devices to negotiate it, so only a solution for currently a very small proportion of devices.
In the late 60's when I was a slightly precocious teenage schoolboy interested in electronics, I convinced my father that I could squeeze a bit more life out of our old black and white TV, that was gradually fading away.
Opening it up I located the mains transformer which, like most in those days, had various taps on it to adjust for slightly different AC mains voltages around the country. I moved the the wire to the next tap, which increased the voltage in by about 10 volts. I switched it on and my father marvelled at the increased brightness of the screen. Maximum brownie points.
Three months later there was a bit of a bang and a burning smell.
Oh well, we needed a new one anyway...
Years ago, when I worked on weather satellite instruments, I was installing a ground test system, made in the US, in the satellite contractor's test control room in Germany. Our system, which was based on a Sun Ultra 5 (or possibly an Ultra 1; it's been a while), was intended to read and interpret instrument data. I carefully checked the display monitor - yup, it was 110/240 V, with auto-switching. Plugged it into the native 220V outlet and cabled it to its system unit - yup, also marked 110/240V. Plugged that into the 220V outlet, too. Pressed the power button: CRACK. Wisp of smoke. Exclamations of dismay. Turns out the system unit, unlike its monitor, was NOT auto-switching!
Fortunately, that particular Ultra chassis used a standard PC-compatible power supply. A quick trip to the local Mega Store later, and we swapped in the replacement supply. Even MORE fortunately, the damage was limited to the power supply itself - which we then buried deep in a cabinet and never spoke of again. Well, I didn't, though there was some light-hearted fun at my expense, which I do suppose I earned. I blame jet lag.
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