* Posts by Strebortrebor

22 publicly visible posts • joined 21 Apr 2018

Elevating cost-cutting to a whole new level with million-dollar bar bills

Strebortrebor

Re: Elevator interface

Differential drivers and receivers such as RS-422 and RS-485 have greater noise immunity than single-ended interfaces such as RS-232. But they won't do diddly for you if there are severe ground loops, or (heaven forbid) a lightning strike. In the '80s I was an engineer at a supplier of wagering systems to horse and dog tracks. The RS-422 line driver and receiver chips were specced at 25 volts common-mode voltage, max. The computer room was typically in the basement of the building. If lightning struck (say) an upper floor of the grandstand, it would let the magic smoke out of serial driver and receiver chips in the terminals and communication processors. The first time it happened, the chip soldered-in at the factory would be replaced in the field by a socket to ease future repairs.

An even more hostile electrical environment was the communication between the infield display board and the computer room. Typically the infield had an artificial lake, so the ground conductivity was very high -- a lightning magnet. A lightning strike to the infield, or to the grandstand, could cause different "ground" voltages between one end of a cable and the other.

Each succeeding generation of display hardware used lower voltage / higher impedance logic than previous ones, so was less and less reliable in hostile weather. 48-volt telephone relays could stand a fair bit of abuse, but the transistors in the computer room that drove them would fail first. Shift registers made of SCRs with 18-volt logic, not as good. TTL logic with RS-422-style line drivers and receivers would fail if there was a storm cloud anywhere in sight. When the Z80 came along and we wanted to respin the display systems, the naysayers in the company said that there was no way we would get a computer to survive in the infield. But fiber optics had become an option. Even though it was pricey, you didn't need many cores. Our stuff Just.Kept.Working in storms that would have taken the older hardware down for days. Fiber saved our bacon; it won't propagate a lightning strike.

That awful moment when what you thought was a number 1 turned out to be a number 2

Strebortrebor

Re: Trying to teach...

I went through this in the '80s, when I worked for a subsidiary of a Fortune 500 company. I created a spreadsheet (Supercalc on CP/M) to do my expense reports and print them out on a Decwriter. Every word and every field was present, in the same relative positions on the page.

The beancounters said that they couldn't accept it in this form, because it was not on the official stationery. I still used the spreadsheet to enter and cross-foot the data, transcribing the output onto the official 3-part NCR form at the end.

Strebortrebor

Re: You solved the problem, goodbye

When I got my first mobile phone, I was offered a short list of available numbers from which to choose. I chose the one that ends in 2048, because it's 2**11. This shortened the string of new digits to memorise. (2716 would have worked the same for me).

I've pointed this out this property to other geeky people to whom I've given my number. It usually doesn't register with them.

Beware the Friday afternoon 'Could you just..?' from the muppet who wants to come between you and your beer

Strebortrebor

My son drove 3 hours (round-trip) recently to sort out a "hard down" situation at a shop. The female end of the line cord had fallen out of the IEC22 connector on the back of their switch. To be fair, when the lights stop blinking on a 2960, it has often been due to a failed internal power supply unit.

A user's magnetic charm makes for a special call-out for our hapless hero

Strebortrebor

Re: Hmmmm

If said magnet was strong enough to deflect the electron beam *entirely off the screen*, that would explain the reported behavior. It's not stated whether the monitor was on a stand, and the magnet placed under the stand, or if it was near the front face of the screen. The closer the magnet was to the CRT's neck, the greater the deflection would be. The degausser's field might have been strong enough to pull enough of the beam onto the screen to create a bit of a distorted image while the degausser was active.

Strebortrebor

degaussed my laprop drive whilst running

It *can* happen here. A couple of years back I was using my laptop to check out a reported cabling issue to a POS terminal (aka cash register) in a department store. I carried the standard fox-and-hound (tone generator and sniffer) and cable mapper to check the continuity on all pairs. In addition, I would use a couple of laptops* to check out the cable in question. I first toned and traced the cable to the wiring closet, connected one laptop in place of the register, and took the other to the wiring closet. When I returned to the register to begin the test, I found that the laptop had blue-screened. Turns out that, space being limited, I had set it down on the cash wrap with the HDD over the magnet that the cashier uses to remove anti-theft tags from the clothing. That drive was toast. the machine was fine with another drive installed.

*It has a Broadcom NIC. Broadcom has a Windows app that can access their NICs' built-in diagnostic capabilities. Among other things, it will tell you the length of each pair, detect split pairs, and tell you the connection speed and duplex. Doesn't do nearly as thorough a cable analysis as a proper tester, but in conjunction with the cable mapper it will often give you a clue as to the location and nature of a fault.

Is that a stiffy disk in your drive... or something else entirely?

Strebortrebor
Facepalm

I'm guilty of that myself. When VGA first came out I connected my first VGA monitor (monochrome) without paying too much attention. It didn't work.

If I recall correctly, they were about to RMA the monitor (cable was permanently attached) before someone asked me to doublecheck the connector orientation.

The pin pattern of the HD15 connector is perfectly symmetrical, so no pins were harmed. It had taken only a little additional force to reshape the metal shell of the male connector into its complementary D shape.

Defense against the Darknet, or how to accessorize to defeat video surveillance

Strebortrebor

Re: Defense against the Darknet

My experience, too. Formerly employed by an Italian manufacturer, was over there for training a couple of times. The official language of the company was English. The German guy, the French guy, the Italian guy would be having a hallway conversation, and this Yank would have a hard time following it due to differences in pronunciation, vocabulary, and grammar.

But then again I've encountered similar difficulty with regional accents in North America -- for example, a late-night encounter with a security guard in Kentucky asking about my rental car: "You in that Fo-wid?" After a couple of repetitions I finally realized that he meant Ford. I hadn't considered the possibility of stretching a word with a single vowel into 2 syllables. In Noo Yawk, where I grew up, fo-wid was the antonym of back-wid.

Take your pick: 0/1/* ... but beware – your click could tank an entire edition of a century-old newspaper

Strebortrebor

Re: Talking of paper...

Used to work at a major North American totalisator company. The (duplex) transaction processing system had 900 line/min Dataproducts printers. They printed intermediate reports every minute, which were not needed unless something broke. Only the final-cycle wagering totals that printed after each race started, and the payout calculations performed after each race's result was determined, were kept; the rest of the printers' greenbar paper output went into 55-gallon trash cans. The operators generally left the printers' acoustic covers off, as they got fewer paper jams that way. Many operators seemed to be half deaf as a result.

I was working on CP/M systems that managed public information displays. I got tired of waiting for source listings on the 30-character-per-second Decwriter serial terminals that were available to me, so I designed and built a card to drive a Dataproducts printer when it was not required for its intended use. It probably took longer to swap the cable than to print one of my listings.

Dataproducts lost our business after they switched their ribbons from towel-style to a cartridge with rollers that attempted to stuff the ribbon in at the end after use. They kept jamming, and the repeated hammering would tear holes in the ribbon in short order. Centronics had recently bought the CDC printer line. While they used the same band character element technology that DP had adopted, they had kept the towel ribbon and that induced us to switch. I'm sure that that salesman ended up quite happy that he cold-called us that day.

Those impact printers probably stayed in service another 10 or 15 years. No doubt it's all laser now.

Blue Monday: Efforts to inspire teamwork with swears back-fires for n00b team manager

Strebortrebor

The name is Bissell

Hugh Jim Bissell.

Credit: The Capital Steps

'Numpty new boy' lets the boss take fall for mailbox obliteration

Strebortrebor
Coat

Re: 100% honesty 90% of the time

Eddies in the space-time continuum.

Mine's the one on the sofa.

If I could turn back time, I'd tell you to keep that old Radarange at home

Strebortrebor

It's likely that the emergency generator had harmonic content that was tripping the cheap clock's zero-crossing detector multiple times per cycle. Or perhaps the generator's output was not as "stiff" (low impedance) as the mains source, allowing harmonics generated by some other load (switching power supply, perhaps?) to propagate when the generator was sourcing power.

My wife's digital alarm clock runs crazy fast when the washer runs. It started when we replaced the old top-loader with a new front-loader. The old one had a mechanical timer and an induction motor. The new one has electronic controls and a direct-drive motor for the drum -- not sure whether it's DC or variable-frequency AC. But whatever it is, the drive electronics must be putting spikes on the power line, causing the clock to run crazy. Our solution was to ignore the clock and use the alarm function of our mobile phones.

When I was in college it was impossible to sleep in on the days they would test the dorm's emergency generator. The exhaust pipe ran up through interior partitions to exit through the roof, and it was so loud that I doubt that it had a muffler. It made an awful blatting noise if you were outside, too.

Haunted disk-drive? This story will give you the chills...

Strebortrebor

Early, full-height 8 inch floppy drives had synchronous spindle motors. We added CP/M systems at field sites that had 10KVA UPSes to support a redundant minicomputer system. Some of the backup disks from field sites were unreadable at the home office. Turns out that these 1970s-vintage UPSes had free-running oscillators and were not crystal-controlled or phase-locked to the mains. The frequency could be off by a couple of hertz, changing the spindle speed proportionately.

We set up an audio oscillator, a 100-watt public-address amplifier, and a transformer to power one of the system's 2 drives, tweaked the frequency until the drive could read reliably, and PIPed the data to a fresh disk in the other drive, which remained powered by the utility.

The later, half-height drives ran on DC and did not have the issue.

Take my advice: The only safe ID is a fake ID

Strebortrebor

A friend claims to have gone to high school with a lad named Richard Puller. One wonders what, or if, his parents were thinking.

Powerful forces, bodily fluids – it's all in a day's work

Strebortrebor

Re: Monitor

I do field service work. A lot of calls read something like "repair/replace the cabling to X". It usually isn't the cable. When it is, it's often the jack, particularly in the deli department or the meat department prep room -- anywhere that's moist or gets washed down. The (supposedly) gold-flashed contacts in the network jack turn green, or the punchdown contacts do. Replace the offending jack, and the problem is solved for a few years.

Some of the companies that hire my services treat me like a monkey with a screwdriver, not trusting my diagnostic skills. Being directed by levels 1, 2, AND 3 of contracted tech support from "Bob" in Bangalore (or wherever) to replace the cable from the modem to the router, and try it again, and again, when it is clear to me that the router's WAN port was fried by the electrical discharge that caused the ISP to replace their modem the previous day, is an exercise in frustration. The restaurant manager said that he'd lost printers and a dishwasher to the same storm. I had the fault diagnosed within 20 minutes of arrival, but it took 4-1/2 hours to persuade their Level 3 that the magic smoke had been let out of the WAN interface, and they needed to send a replacement router. I console myself with the fact that I am paid hourly for these gigs.

I carry a $50 cable mapper that will detect some of the gross faults. High-end cable certifiers are pricey and hard to justify. But I have a laptop with a Broadcom network interface, and a copy of Broadcom Advanced Control Suite (BACS). This software uses the NIC's inherent diagnostic capability to perform cable analysis, I assume through time-domain reflectometry. It will tell you the length of each pair in meters (the measured lengths vary due to different number of twists per foot from one pair to the next, to reduce crosstalk). It also detects crossed pairs (such as when you misread the colors and exchange the white-of-blue for the white-of-green, for example). It seems to be accurate to within a meter or so.

It's not calibrated, certainly not traceable to NIST standards, but it will give me enough indication that the fault is at the near or the far end of the cable (or, in one case, 50 feet from one end) that I bring it to all the gigs. It is quite persuasive to be able to say "My laptops connected to each other at 1Gb/s over that cable, and cable analysis didn't show any faults".

I've made adapters to be able to test telephone cables terminated in 6-position jacks, and even CCTV coaxial cable, using it. The velocity factor of other cable types may differ from Cat5, throwing the length measurement off. But it's certainly good enough to tell you whether it's the near, or the far, end of the coax that has the badly-crimped connector. If you care to know the actual length, use BACS to analyze a known length of the cable in question, and divide the measured by the actual length to get a correction factor.

So give that old Dell D610 a new life as a cable analyzer, or get a more modern (and portable) device such the Pockethernet, so you can have some more substantial evidence to point to and get those outsourced cabling guys to do their job right the first time.

Attempt to clean up tech area has shocking effect on kit

Strebortrebor
Coat

Re: It's not always the cleaners

I've recently done some site surveys for which I signed papers in which I agreed to wear safety shoes, high-vis, hard hat, and safety glasses, among other things. . . to do a site survey in which I was taking photographs and notes in the network closets of a big-box retail store.

The high-vis did seem to be an effective deterrent to customers buttonholing me to ask product questions, which they otherwise tend to do when they see someone wearing a badge.

Mine's the high-vis one.

Sysadmin misses out on paycheck after student test runs amok

Strebortrebor

Re: Naming Schemes

You missed Intercourse (Pennsylvania), which is not far from Paradise, Blue Ball, and Bird-In-Hand.

Then again, there's Boring (Maryland).

Strebortrebor
Facepalm

Re: Nice but dim

Just last weekend I was sent over an hour away to a shop that had lost network connectivity to one of its cash register servers. The machine was up, but there was no link light. Got out the cable tester; it showed open circuit on all pairs. I poked around and discovered a patch cord plug that wasn't fully seated in its jack. Shoved it that extra millimeter home, the latch caught with a snap, and I was a genius.

I was told that it had been installed 2 weeks previously, and had been working fine. Just took that long to creep out far enough to lose connectivity.

Had to buy my own cuppa, but hey -- emergency overtime!

A flash of inspiration sees techie get dirty to fix hospital's woes

Strebortrebor
Coat

Well... Inflammable is the original word, from the Latin, I think, meaning "capable of becoming inflamed, a.k.a. being set afire". The "in" part is not a negative in this context. So non-inflammable is only a single negative. But the poorly-educated didn't understand this, so the back formation "flammable" was created (by the lawyers, I suspect). Perhaps if the original had been spelled "enflammable" the confusion would not have existed in the first place. I blame the Académie Anglaise for not properly instructing (by analogy, structing?) us in the first place.

Mine's the Nomex one.

Trainee techie ran away and hid after screwing up a job, literally

Strebortrebor
Facepalm

I did something similar at my daughter's apartment recently. Hung a shelf on the outside wall of the bathroom. Used the toggling plastic wall anchors and screws provided with it. Didn't notice that the screws were long enough to catch the pocket door, until someone went to close the door to use the facility. Was able to cut off the tip of the screw for clearance, once the plastic toggle had been drawn up. I still owe Mr. Landlord a spackle-and-paint repair of the door.

Admin needed server fast, skipped factory config … then bricked it

Strebortrebor
Facepalm

I once inserted a 2716 backward. Got an awesome white glow through the window. Powered down quickly. Blistered my fingertip. Just for yucks, I reinserted it the right way 'round after it had cooled. Much to my surprise, the d**ned thing worked.

Tech bribes: What's the WORST one you've ever been offered?

Strebortrebor
WTF?

Rusty pens

We were looking to install fiber optic links from one building to another to get away from stuff getting all blowed up when there was a lightning strike. The AT&T sales dude who called on us apologized for the pens that he was about to give us. They were starting to rust, inside their cheesy packaging, Death Star logo and all. We took them off his hands to help him get rid of them. They didn't write so well, either.

We didn't buy his fiber optic connectors, for other reasons.