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.
[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?
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.
With tools, especially cordless tools, you’re going to pay now or pay later. On one hand, you can spend a bunch of money up front and get a quality tool that will last a long time. The other option is purchasing a cheap cordless tool that won’t last long, having to replace it later and thus spending more money. With cheap cordless tools it is common for the battery to fail before the physical tool making that tool completely unusable. Sure, another battery could be purchased but sometimes they cost just as much as the tool and battery combo originally did. So what’s a cordless tool user to do?
[EngergySaver] had a set of DeWalt cordless tools with a bunch of working batteries. He also had a cheap drill where the battery had died. His bundle of tools included two flashlights, one of which the case physically broke in half, probably from a clumsy drop. Instead of tossing the broken flashlight pieces in the garbage, [EngergySaver] kept them around for a while. Then one day he had the idea of combining the base of the broken DeWalt flashlight with the top of the old battery-less drill. He had the parts so why not?
The battery pack was 18 volt and the cheap drill expected 16.8 volts. [EngergySaver] figured the voltages were close enough and decided not to worry about the difference during his hack. He started by disassembling both the drill and flashlight down to the bare plastic housings. He marked an appropriate place to splice the handles and made some cuts. After the wiring was spliced together and the tool casings reassembled, a piece of sheet metal was cut and bent around the handle at the joint between flashlight and drill. Hose clamps hold the sheet metal tight around the handles, keeping the new hybrid tool together. And although we’re not crazy about the sheet metal and hose clamp method, it seems to be working just fine. With a little work and ingenuity [EngergySaver] resurrected an old tool for our favorite price; $0.
We’re suckers for repair videos and this Dewalt worksite radio repair (YouTube Link) from Hackaday alum [Todd Harrison] is no exception. Like a detective story, we’re always trying to guess who did it.
In his first video [Todd] traced the issue down to a faulty 6 volt regulator which was pushing out 8 volts. He fixed that by hacking a LM317 into the circuit to replace the original non-adjustable part. That helped but after a few days the radio failed again. So here he traced out the voltages to find the second culprit. Along the way, we get to see some of the nicer features of his Fluke 87 and 289 meters. As well as puzzling over the some of the design decisions in the radios construction, before identifying the final issue.
We won’t spoil the surprise, but find out how Todd solves this riddle, wrapped in a mystery, inside an enigma in the video below!
It’s always nice to see hackers pick up stuff headed for the landfill and put it back in action with a quick repair and upgrade. [Septillion] found a wireless remote controlled AC outlet in the junk bin and decided to do just that. A nice spin-off of such hacks is that we end up learning a lot about how things work.
His initial tests showed that the AC outlet and its remote could be revived, so he set about exploring its guts. These remote AC outlets consist of an encoder chip on the remote and a corresponding decoder chip on the outlet, working at 433MHz. Since the various brands in use have a slightly different logic, it needed some rework to make them compatible. The transmit remote was a quick fix – changing the DIP switch selected address bits from being pulled low to high and swapping the On and Off buttons to make it compatible with the other outlets.
Working on the AC outlet requires far more care and safety. The 230V AC is dropped down using a series capacitor, so the circuit is “hot” to touch. Working on it when it is powered up requires extreme caution. A quick fix would have been to make the changes to the address bits and the On/Off buttons to reflect the changes already made in the remote transmitter. Instead, he breadboarded a small circuit around the PIC12F629 microcontroller to take care of the data and address control. Besides, he wanted to be able to manually switch the AC outlet. The relay control from the decoder was routed via the microcontroller. This allowed either the decoder or the local manual switch from controlling the relay. Adding the PIC also allowed him to program in a few additional modes of operation, including one which doubled the number of outlets he could switch with one remote.
[MattisLind] spent one and a half years to complete restoration of a Digital Equipment Corporation (DEC) PDP-11/04 including peripherals like a TU60 tape drive and a LA30P Decwriter printing terminal. The computer is now able to run CAPS-11 which is a very simple operating system and also CAPS-11/BASIC. Just like the project itself, his blog post is quite long filled with interesting details. For a tl;dr version, check the video after the break.
This system originally belonged to Ericsson and [MattisLind] received it from Ericsson computer club, EDKX. He was lucky to have access to online resources which made the task easier. But it still wasn’t easy considering the number of hardware faults he had to tackle and the software challenges too. The first task was obviously looking at the Power supply. He changed the big electrolytic capacitors, and the power supply seemed to work well with his dummy load, but failed when hooked up to the backplane of the computer. Some more digging around, and a replaced thyristor later, he had it fixed. The thyristor was part of a crowbar circuit to protect the system from over-voltages should one of the main switching transistors fail.
With the power supply fixed, the CPU still wouldn’t boot. Some sleuthing around, and he pin pointed the bus receiver chip that had failed. His order of the device via a Chinese ebay seller was on the slow boat, so he just de-soldered a device from another board which improved things a bit, but it was still stuck in a loop. A replacement communications board and the system now passed diagnostics check, but failed memory testing. This turned out to be caused be a faulty DIP switch. He next tackled all the software challenges in getting the CPU board up to speed.