Looking in the back of the Tektronix 577

Repairing A Tektronix 577 Curve Tracer

Over on his YouTube channel our hacker [Jerry Walker] repairs a Tektronix 577 curve tracer.

A curve tracer is a piece of equipment which plots I-V (current vs voltage) curves, among other things. This old bit of Tektronix kit is rocking a CRT, which dates it. According to TekWiki the Tektronix 577 was introduced in 1972.

In this repair video [Jerry] goes to use his Tektronix 577 only to discover that it is nonfunctional. He begins his investigation by popping off the back cover and checking out the voltages across the voltage rails. His investigations suggest a short circuit. He pushes on that which means he has to remove the side panel to follow a lead into the guts of the machine.

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Battery Repair By Reverse Engineering

Ryobi is not exactly the Cadillac of cordless tools, but one still has certain expectations when buying a product. For most of us “don’t randomly stop working” is on the list. Ryobi 18-volt battery packs don’t always meet that expectation, but fortunately for the rest of us [Badar Jahangir Kayani] took matters into his own hands and reverse-engineered the pack to find all the common faults– and how to fix them.

[Badar]’s work was specifically on the Ryobi PBP005 18-volt battery packs. He’s reproduced the schematic for them and given a fairly comprehensive troubleshooting guide on his blog. The most common issue (65%) with the large number of batteries he tested had nothing to do with the cells or the circuit, but was the result of some sort of firmware lock.

It isn’t totally clear what caused the firmware to lock the batteries in these cases. We agree with [Badar] that it is probably some kind of glitch in a safety routine. Regardless, if you have one of these batteries that won’t charge and exhibits the characteristic flash pattern (flashing once, then again four times when pushing the battery test button), [Badar] has the fix for you. He actually has the written up the fix for a few flash patterns, but the firmware lockout is the one that needed the most work.

[Badar] took the time to find the J-tag pins hidden on the board, and flash the firmware from the NXP micro-controller that runs the show. Having done that, some snooping and comparison between bricked and working batteries found a single byte difference at a specific hex address. Writing the byte to zero, and refreshing the firmware results in batteries as good as new. At least as good as they were before the firmware lock-down kicked in, anyway.

He also discusses how to deal with unbalanced packs, dead diodes, and more. Thanks to the magic of buying a lot of dead packs on e-Bay, [Badar] was able to tally up the various failure modes; the firmware lockout discussed above was by far the majority of them, at 65%. [Badar]’s work is both comprehensive and impressive, and his blog is worth checking out even if you don’t use the green brand’s batteries. We’ve also embedded his video below if you’d rather watch than read and/or want to help out [Badar] get pennies from YouTube monetization. We really do have to give kudos for providing such a good write up along with the video.

This isn’t the first attempt we’ve seen at tearing into Ryobi batteries. When they’re working, the cheap packs are an excellent source of power for everything from CPap machines to electric bicycles.

Thanks to [Badar] for the tip.

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Silent Speak And Spell Gets Its Voice Back

While talking computers are old hat today, in 1978, a talking toy like the Speak and Spell was the height of novel tech. [Kevin] found a vintage one, but it didn’t work. It looked like someone had plugged in the wrong power adapter, leading to, undoubtedly, one or more unhappy children. There was some damage that suggests someone had already tried to repair it, but without success.

In addition to effecting the repair, [Kevin] took lots of pictures, so if you ever wanted to peek inside one of these, this is your chance. The case had no screws, just clips, although apparently some of the newer models did have some screws.

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Teufel Introduces An Open Source Bluetooth Speaker

There are a ton of Bluetooth speakers on the market. Just about none of them have any user-serviceable components or replacement parts available. When they break, they’re dead and gone, and you buy a new one. [Jonathan Mueller-Boruttau] wrote in to tell us about the latest speaker from Teufel Audio, which aims to break this cycle. It’s a commercial product, but the design files have also been open sourced — giving the community the tools to work with and maintain the hardware themselves.

The project is explained by [Jonathan] and [Erik] of Teufel, who were part of the team behind the development of the MYND speaker. The basic idea was to enable end-user maintenance, because the longer something is functioning and usable, the lower its effective environmental footprint is. “That was why it was very important for us that the MYND be very easy to repair,” Erik explains. “Even users without specialist knowledge can replace the battery no problem.” Thus, when a battery dies, the speaker can live on—versus a regular speaker, where the case, speakers, and electronics would all be thrown in the garbage because of a single dead battery. The case was designed to be easy to open with minimal use of adhesives, while electronic components used inside are all readily available commercial parts.

Indeed, you can even make your own MYND if you’re so inclined. Firmware and hardware design files are available on GitHub under the Creative Commons Attribution-ShareAlike 4.0 International (CC BY-SA 4.0) license for those looking to repair their speakers, or replicate them from the ground up. The company developed its own speaker drivers, but there’s nothing stopping you from using off-the-shelf replacements if so desired.

It’s a strategy we expect few other manufacturers to emulate. Overall, as hackers, it’s easy to appreciate a company making a device that’s easy to repair, rather than one that’s designed to frustrate all attempts made. As our own Jenny List proclaimed in 2021—”You own it, you should be able to fix it!” Sage words, then as now!

Arduino Saves Heat Pump

For home HVAC systems, heat pumps seem to be the way of the future. When compared to electric heating they can be three to four times more efficient, and they don’t directly burn fossil fuels. They also have a leg up over standard air conditioning systems since they can provide both cooling and heating, and they can even be used on water heating systems. Their versatility seems unmatched, but it does come at a slight cost of complexity as [Janne] learned while trying to bring one back to life.

The heat pump here is a Samsung with some physical damage, as well as missing the indoor half of the system. Once the damage to the unit was repaired and refilled with refrigerant, [Janne] used an Optidrive E3 inverter controlled by an Arduino Mega to get the system functional since the original setup wouldn’t run the compressor without the indoor unit attached. The Arduino manages everything else on the system as well including all of the temperature sensors and fan motor control.

With everything up and running [Janne] connected the system to a swimming pool, which was able to heat the pool in about three hours using 60 kWh of energy. The system is surprisingly efficient especially compared to more traditional means of heating water, and repairing an old or damaged unit rather than buying a new one likely saves a significant amount of money as well. Heat pump projects are getting more common around here as well, and if you have one in your home take a look at this project which adds better climate control capabilities. to a wall mount unit.

Tektronix TDS8000 banner

Repairing An Old Tektronix TDS8000 Scope

Over on his YouTube channel our hacker [CircuitValley] repairs an old TDS8000 scope.

The TDS8000 was manufactured by Tektronix circa 2001 and was also marketed as the CSA8000 Communications Signal Analyzer as well as the TDS8000 Digital Sampling Oscilloscope. Tektronix is no longer manufacturing and selling these scopes but the documentation is still available from their website, including the User Manual (268 page PDF), the Service Manual (198 page PDF), and some basic specs (in HTML).

You can do a lot of things with a TDS8000 scope but particularly its use case was Time-Domain Reflectometry (TDR). A TDR scope is the time-domain equivalent of a Vector Network Analyzer (VNA) which operates in the frequency-domain.

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A Bicycle Is Abandonware Now? Clever Hack Rescues Dead Light

A bicycle is perhaps one of the most repairable pieces of equipment one can own — no matter what’s wrong with it, and wherever you are on the planet, you’ll be able to find somebody to fix your bike without too much trouble. Unfortunately as electric bikes become more popular, predatory manufacturers are doing everything they can to turn a bike into a closed machine, only serviceable by them.

That’s bad enough, but it’s even worse if the company happens to go under. As an example, [Fransisco] has a bike built by a company that has since gone bankrupt. He doesn’t name them, but it looks like a VanMoof to us. The bike features a light built into the front of the top tube of the frame, which if you can believe it, can only be operated by the company’s (now nonfunctional) cloud-based app.

The hack is relatively straightforward. The panel for the VanMoof electronics is removed and the works underneath are slid up the tube, leaving the connector to the front light. An off the shelf USB-C Li-Po charger and a small cell take the place of the original parts under a new 3D printed panel with a switch to run the light via a suitable resistor. If it wasn’t for the startling green color of the filament he used, you might not even know it wasn’t original.

We would advise anyone who will listen, that hardware which relies on an app and a cloud service should be avoided at all costs. We know most Hackaday readers will be on the same page as us on this one, but perhaps it’s time for a cycling manifesto to match our automotive one.

Thanks [cheetah_henry] for the tip.