Repairing $55,000 of Vintage Core Memory

If you find yourself in the vicinity of Mountain View, California you really should stop by the Computer History Museum. Even if you aren’t into the retrocomputer scene, there’s so much cool hardware ranging from a replica of the Babbage engine to nearly modern PCs. There’s even a room dedicated to classic video games. There are two fully working old computers at the museum that have their own special rooms: a PDP-1 (complete with vector scope to run Space War) and an IBM 1401.

The IBM 1401 looks like big iron, but in its day it was a low-end machine (costing an innovative business about $2500 a month). The base unit had 4000 words of magnetic core memory, but if you had a hankering for more memory, you could add the 350 pound dishwasher-sized IBM 1406 (for only $1575 a month or you could buy for $55100). How much memory did you get for $18900 a year? An extra 12000 words!

The problem is, the museum’s 1406 had developed a problem. Some addresses ending in 2, 4 or 6 failed and they were all in the same 4K block. [Ken Shirriff] was asked to go in and try to find the problem. We don’t want to give away the story, but [Ken] wrote up his experience (with lots of pictures).

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Hacking when it Counts: Much Space Station Hacking Saved Skylab

Thanks to the seminal work of Howard and Hanks et al, the world is intimately familiar with the story behind perhaps the most epic hack of all time, the saving of the crippled Apollo 13 mission. But Apollo 13 is far from the only story of heroic space hacks. From the repairs to fix the blinded Hubble Space Telescope to the dodgy cooling system and other fixes on the International Space Station, both manned and unmanned spaceflight can be looked at as a series of hacks and repairs.

Long before the ISS, though, America’s first manned space station, Skylab, very nearly never came to fruition. Damaged during launch and crippled both electrically and thermally, the entire program was almost scrapped before the first crew ever arrived. This is the story of how Skylab came to be, how a team came together to fix a series of problems, and how Skylab went on to success despite having the deck stacked against her from the start.

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Macintosh Hard Drive Repair

The Macintosh II was a popular computer in the era before Apple dominated the coffee shop user market, but for those of us still using our Mac II’s you may find that your SCSI hard drive isn’t performing the way that it should. Since this computer is somewhat of a relic and information on them is scarce, [TheKhakinator] posted his own hard drive repair procedure for these classic computers.

The root of the problem is that the Quantum SCSI hard drives that came with these computers use a rubber-style bump stop for the head, which becomes “gloopy” after some time. These computers are in the range of 28 years old, so “some time” is relative. The fix involves removing the magnets in the hard drive, which in [TheKhakinator]’s case was difficult because of an uncooperative screw, and removing the rubber bump stops. In this video, they were replaced with PVC, but [TheKhakinator] is open to suggestions if anyone knows of a better material choice.

This video is very informative and, if you’ve never seen the inside of a hard drive, is a pretty good instructional video about the internals. If you own one of these machines and are having the same problems, hopefully you can get your System 6 computer up and running now! Once you do, be sure to head over to the retro page and let us know how you did!

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Neato Botvac LiDAR Repair Includes Juicy Pics and a Tool Hack

It seems second nature to us and it’s one of the ways we hackers are different from the larger population… sometimes we absolutely insist on buying something that is already broken. Which is where we join [Anton] as he reverse engineers, debugs, and repairs a broken Neato Botvac’s LiDAR system all in the name of having clean floors at a fraction of the cost.

Now keep your head on a swivel ’cause along the way [Anton] has the all-too familiar point in his repair where he puts the original project on hold while he makes a specialized tool he needs to finish the job. It’s hard to tell which is more impressive: turning a laptop webcam into a camera capable of clearly viewing bond wires and (wait for it!) where they are attached on the Silicon, or that he (yeah, we were making a comparison…member?) went straight back to solving the original problem. [Anton] did split this project into two separate blog posts, the first one is linked above and it’s not until the second post that he fixes the original problem. Perhaps there was a bit of scope creep, which was the reason for the separate blog entries? At any rate, [Anton] does a great job documenting the process along with what he calls some ‘juicy pictures’ and you can see a few of them after the break.

It’s been a while since we’ve seen a Neato hack (there’s pun in there somewhere, commenters below us will surely wipe the floor with it). LiDar on the other hand has been covered more recently in a Police LiDAR Tear Down and another post relating more directly to [Anton’s] repair.

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No user Serviceable Parts Inside? The rise of the Fix-It Culture

pix-tv-repair-shop
[Source: 1950s Television]
My first job out of high school was in a TV shop. I was hired mainly for muscle; this was the early 1980s and we sold a lot of console TVs that always seemed to need to be delivered to the third floor of a walk up. But I also got to do repair work on TVs and stereos, and I loved it. Old TVs from the 60s and 70s would come in, with their pre-PCB construction and hand-wired chassis full of terminal strips and point to point wiring that must have been an absolute nightmare to manufacture. We’d replace dodgy caps, swap out tubes, clean the mechanical tuners, and sometimes put a new picture tube in  – always the diagnosis that customers dreaded the most, like being told they’d need a heart transplant. We kept those old sets alive, and our customers felt like they were protecting their investment in their magnificent Admiral or Magnavox console with the genuine – and very, very heavy – walnut cabinet.

I managed to learn a lot from my time as a TV repairman, and I got the bug for keeping things working well past the point which a reasonable person would recognize as the time to go shopping for a new one. Fixing stuff is where I really shine, and my house is full of epic (in my mind, at least) repairs that have saved the family tens of thousands of dollars over the years. Dishwasher making a funny noise? I’ll just pull it out to take a look. You say there’s a little shimmy in the front end when you brake? Pull the car into the garage and we’ll yank the wheels off. There’s basically nothing I won’t at least try to fix, and more often than not, I succeed.

I assumed that my fix-it bug made me part of a dying breed of cheapskates and skinflints, but it appears that I was wrong. The fix-it movement seems to be pretty healthy right now, fueled in part by the explosion in information that’s available to anyone with basic internet skills.

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Saving an Alarm System Remote and $100

[Simon] has been using his home alarm system for over six years now. The system originally came with a small RF remote control, but after years of use and abuse it was finally falling apart. After searching for replacement parts online, he found that his alarm system is the “old” model and remotes are no longer available for purchase. The new system had similar RF remotes, but supposedly they were not compatible. He decided to dig in and fix his remote himself.

He cracked open the remote’s case and found an 8-pin chip labeled HCS300. This chip handles all of the remote’s functions, including reading the buttons, flashing the LED, and providing encoded output to the 433MHz transmitter. The HCS300 also uses KeeLoq technology to protect the data transmission with a rolling code. [Simon] did some research online and found the thew new alarm system’s remotes also use the same KeeLoq technology. On a hunch, he went ahead and ordered two of the newer model remotes.

He tried pairing them up with his receiver but of course it couldn’t be that simple. After opening up the new remote he found that it also used the HCS300 chip. That was a good sign. The manufacturer states that each remote is programmed with a secret 64-bit manufacturer’s code. This acts as the encryption key, so [Simon] would have to somehow crack the key on his original chip and re-program the new chip with the old key. Or he could take the simpler path and swap chips.

A hot air gun made short work of the de-soldering and soon enough the chips were in place. Unfortunately, the chips have different pinouts, so [Simon] had to cut a few traces and fix them with jumper wire. With the case back together and the buttons in place, he gave it a test. It worked. Who needs to upgrade their entire alarm system when you can just hack the remote?

Find and Repair a 230kV 800Amp Oil-Filled Power Cable Feels Like Mission Impossible

How do you fix a shorted cable ? Not just any cable. An underground, 3-phase, 230kV, 800 amp per phase, 10 mile long one, carrying power from a power station to a distribution centre. It costs $13,000 per hour in downtime, counting 1989 money, and takes 8 months to fix. That’s almost $75 million. The Los Angeles Department of Water and Power did this fix about 26 years ago on the cable going from the Scattergood Steam Plant in El Segundo to a distribution center near Bundy and S.M. Blvd. [Jamie Zawinski] posted details on his blog in 2002. [Jamie] a.k.a [jwz] may be familiar to many as one of the founders of Netscape and Mozilla.

To begin with, you need Liquid Nitrogen. Lots of it. As in truckloads. The cable is 16 inch diameter co-axial, filled with 100,000 gallons of oil dielectric pressurised to 200 psi. You can’t drain out all the oil for lots of very good reasons – time and cost being on top of the list. That’s where the LN2 comes in. They dig holes on both sides (20-30 feet each way) of the fault, wrap the pipe with giant blankets filled with all kind of tubes and wires, feed LN2 through the tubes, and *freeze* the oil. With the frozen oil acting as a plug, the faulty section is cut open, drained, the bad stuff removed, replaced, welded back together, topped off, and the plugs are thawed. To make sure the frozen plugs don’t blow out, the oil pressure is reduced to 80 psi during the repair process. They can’t lower it any further, again due to several compelling reasons. The cable was laid in 1972 and was designed to have a MTBF of 60 years.

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