Vintage Meter Repair? It’s Easier With X-Rays

March 6, 2022 by Donald Papp 18 Comments

Here’s an interesting and detailed teardown and repair of a Keithley 2001 7.5 Digit multimeter that is positively dripping with detail. It’s also not every day that we get to see someone using x-ray imaging to evaluate the extent of PCB damage caused by failed electrolytic capacitors.

Dark area is evidence of damage in the multi-layer PCB.

Sadly, this particular model is especially subject to that exact vintage electronics issue: electrolytic capacitor failure and leakage. These failures can lead to destroyed traces, and this particular unit had a number of them (in addition to a few destroyed diodes, just for good measure.) That’s where the x-ray machine comes in handy, because some of the damage is hidden inside the multi-layer PCBs.

[Shahriar], perhaps best known as [The Signal Path], narrates the entire process of fixing up the high-quality benchtop multimeter in a video, embedded below (or you can skip directly to the x-ray machine being broken out.) [Shahriar] was able to repair the device, thanks in part to it being in relatively good shape, and having the right tools available. Older electronics are not always so cooperative; the older a device is, the more likely one is to run into physical and logical standards that no longer exist.

Continue reading “Vintage Meter Repair? It’s Easier With X-Rays” →

Multimeters Go Big Screen

December 7, 2021 by Al Williams 54 Comments

We’ve noticed lately that some cheap meters have gone to having big colorful screens. The screens aren’t dot matrix, but still have lots of graphics that could be useful or could be distracting eye candy, depending. The really cheap ones seem more like a gimmick, but [OM0ET] took a look at one that looked like a fair midrange instrument with some useful display features, the GVDA GD128.

A lot of the display shows the current function of the meter. No need for an expensive multiposition switch or rows of interlocking pushbuttons. Many of these new meters also have non-contact voltage sensors, which is handy. Otherwise, it looks like a pretty conventional cheap meter. Continue reading “Multimeters Go Big Screen” →

Handheld Multimeter Converted For Bench Top Use

May 31, 2021 by Chris Lott 14 Comments

A few years ago [Mechatrommer] got one of the low-cost Aneng Q1 multimeters and has converted it into a bench top meter. He first tried and failed to do an LCD modification and set it aside. It remained in a storage box until he needed another meter to repair his rubidium frequency standard. Finding that off-the-shelf bench multimeters were literally off-the-shelf — they were too deep for his bench — he decided to take matters into his own hands.

He dug out the dismantled an Aneng Q1 and undertook a more drastic modification than before, slicing the multimeter into three pieces and mounting each piece in a new enclosure. The power-draining back-lit display of the Q1, problematic in a battery-powered handheld meter, isn’t an issue in a bench top design. [Mechatrommer] replaced the battery pack with a mains powered supply. Next he reconnected all the signals which had been interrupted by the bandsaw, and now the meter lives again.

The resulting meter is pleasing enough (ignore the sideways input jacks) and looks like a typical piece of home-brew test gear. The enclosure has a lot of empty space, which he uses to stow test leads and sandwiches (we saw a similar storage compartment in [Dave Jones]’s recent teardown of a portable Fluke 37 multimeter). Kudos to [Mechatrommer] for coming up with this unusual conversion project.

We’ve written about the differences between these low-cost and more professional multimeters before if you want to learn more.

Thanks to [Adrian] for the tip.

Ode To An AVO 8 Multimeter

October 27, 2020 by Jenny List 41 Comments

I’m moving, and in the process of packing all of my belongings into storage boxes to disappear into a darkened room for the next year. Perhaps I could become one of those digital nomads I hear so much about and post my Hackaday stories from a sun-kissed beach while goldfish shoals nibble at my toes. But here in a slightly damp British autumn, box after box of a lifetime’s immersion in tech needs sorting and directing. Why on earth did I hang on to three Philips N1500 VCR system video cassette recorders from the early 1970s! (Don’t worry, those have found a good home.)

Say Hello To An Old Friend Of Mine

As I was packing up my bench, I happened upon a multimeter. I have quite a few multimeters and this isn’t the first time I’ve written about these indispensable instruments, but this one’s a little special.

It’s a treasure from my youth, that most venerable of British test equipment: the AVO 8. This was the ubiquitous multimeter to be found in all manner of electrical and electronic workshops across most of the 20th century, and remains to this day one of the highest quality examples of its type.

It’s a relatively huge Bakelite box about 190mm x 170mm x 100mm in size, and it is instantly recognisable by its dual rotary selector switches and the window for viewing the needle, which forms a characteristic circular arc kidney shape.

The earliest ancestors of my meter appeared in the 1920s, and the first model 8 in the early 1950s. Mine is a Mk III that a penciled date on the inside of its meter movement tells me was made in November 1965 and which I bought reconditioned from Stewart of Reading in about 1991, but manufacture continued until the last Mk VIII rolled off the production line in 2008. It’s to my shame that my AVO is a bit dusty and that maybe I haven’t used it much of late, but as I picked it up all the memories of using it to fix dead TV sets and set up optimistic experiments in radio came flooding back. If there’s one instrument that connects me to the youthful would-be electronic engineer that I once was, then here it is. Continue reading “Ode To An AVO 8 Multimeter” →

In Praise Of The DT830, The Phenomenal Instrument You Probably Don’t Recognise For What It Is

September 24, 2020 by Jenny List 132 Comments

If we had to make a guess at the single piece of electronic bench equipment owned by the highest proportion of Hackaday readers, it would not be a budget oscilloscope from Rigol, nor would it be a popular portable soldering iron like the TS100. Instead we’re guessing that it’s a multimeter, and not even the most accomplished one.

The DT830 is a genericised Chinese-manufactured 3.5 digit digital multimeter that can be had for an astonishingly low price. Less than a decent hamburger gets you an instantly recognisable plastic case with a chunky rotary range selector switch, and maybe a socket for some kind of transistor or component tester. Make sure that there is a 9 volt battery installed, plug in the pair of test leads, and you’re in business for almost any day-to-day electrical or electronic measurement. They’ve been available in one form or another for decades and have been the subject of innumerable give-aways and loss-leader offers, so it’s a reasonsble guess that you’ll have one somewhere. I have three as far as I know, they make great on-the-go instruments and have proved themselves surprisingly reliable for what they are. Continue reading “In Praise Of The DT830, The Phenomenal Instrument You Probably Don’t Recognise For What It Is” →

E-Textile Tools Get The Multimeter Hookup

September 19, 2020 by Kristina Panos No comments

[Irene Posch] has done some incredible work with knitted, crocheted, and fabric circuits — check out the crocheted ALUs and embroidered computer for starters. Now, it seems [Irene] is building up a how-to catalog of e-textile tools that can be easily connected to a multimeter.

So far, this toolbox includes a seam ripper and a crochet hook. The concept is similar for both — print out a handle and connect the tool to a banana jack that can then be connected to a multimeter. The crochet hook is simple: just print out the handle, jam the hook in one end, and stick a mini banana jack in the other end. They’re designed to butt up against each other and make a connection without wires.

Building the ripper takes a bit more effort. There’s another printed handle involved, but you must first free the seam ripper from its stock plastic handle and solder a wire to it. Then twist the other end of the wire around a banana jack and and put that in the other end of the handle.

It’s great to see a little bit insight into the troubleshooting tools of e-textiles, especially because they are all-around fiddly. It all starts with a circuit, so why not do your prototyping with a thread-friendly breadboard?

Play A Game Of Multimeter

September 5, 2020 by Jenny List 4 Comments

There are many different single board computers that are general purpose, but there’s another breed targeted at specific applications. One such is the Clockworkpi, a handheld Game Boy-style games console, which may be aimed at gamers but has just as much ability to do all the usual SBC stuff. It’s something [UncannyFlanigan] has demonstrated, by turning the Clockworkpi into a multimeter. And it’s not just a simple digital multimeter either, it’s one that sports graphing as well as instantaneous readings.

At its heart is an Arduino board that supplies the analogue to digital conversion, with opto-couplers for isolation between the two boards. A simple three-way switch selects voltage, current, and resistance ranges, and the ClockworkPi interface is written in Python. We can see that this could easily be extended using the power of the Arduino to deliver more functionality, for which all the code is handily available in a GitHub repository. It’s not a perfect multimeter yet because it lacks adequate input protection, but it shows a lot of promise.

If you’re intrigued by this project then maybe you’ll be pleased to know that it’s not the first home made multimeter we’ve featured.