multimeter

83 Articles

Multimeter Gets Socket Upgrade To Use Nicer Probes

December 20, 2024 by 9 Comments

[Piffpaffpoltrie] had a problem. They found the InLine VA40R to be a perfectly usable multimeter, except for a couple of flaws. Most glaring among these were the tiny sockets for the test probes. These proved incompatible with the probes they preferred to use, so naturally, something had to be done. 

The desire was to see the multimeter work with [Piffpaffpoltrie]’s connector of choice: the 4 mm Multi Contact banana plug from Stäubli. Swiss-made, gold-plated, and highly reliable, nothing else would do. The original sockets on the multimeter were simply too small to properly accept these, so to make them work, they were machined down, drilled, tapped, and then fitted with a short M3 screw which was then soldered in place. This short length of thread then allowed the new sockets to bolt right into the PCB in place of the original sockets.

Ultimately, many would just buy a new multimeter. This hack is a fiddly and time-consuming one, but it’s kind of neat to see someone go to such lengths to customize their tools to their own satisfaction.

We don’t see a lot of multimeter hacks, because these tools usually get all the necessary features from the manufacturer. Still, the handful we’ve featured have proven most interesting. If you’re tinkering away at customizing your own test gear, don’t hesitate to drop us a line!

Fluke Meter Fails With A Simple Problem

December 4, 2024 by 19 Comments

[TheHWcave] found a Fluke 27 multimeter that looked like it had had quite a rough life. At first, the display flashed an overload indicator until he gave it a good smack—or, as he likes to call it, percussive maintenance. Even then, it would not give good readings, so it was time to open it up.

The display did work, so the obvious theory was something wrong with the analog board. Removing the shields showed what looked like a normal enough PCB. Or at least, the components looked fine. But on the solder side of the board, there was some corrosion on two contacts, so some careful cleaning and resoldering fixed the meter to be as good as new on at least some scales.

Tracing the pins, the corrosion put a resistor between two pins of an op-amp. The only remaining problem was the milliamp scale, but that was a simple blown fuse in the line. Since it was working, it was worth some time to clean up the ugly exterior, which is only cosmetic but still worth a little effort. He left the plastic case cracked and beaten, but he put a lot of effort into clearing up the display window.

You might wonder why you’d fix a meter when you can get one so cheap. However, these name-brand meters are high-quality and new, quite expensive. Even older ones can be worth the effort. While you usually don’t need an X-ray machine to fix something like this, it can’t hurt.

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It’s A Soldering Iron! It’s A Multimeter! Relax! It’s Both!

November 15, 2024 by 22 Comments

Imagine this. A young person comes to you wanting to get started in the electronic hobby. They ask what five things should they buy to get started. Make your list. We’ll wait. We bet we can guess at least two of your items: a multimeter, and a soldering iron. [LearnElectroncsRepair] recently showed us a review of the Zotek Zoyi ZT-N2 which is a soldering iron and a multimeter in one unit. You can watch the video review below.

Honestly, when we heard about this, we didn’t think much of the combination. It doesn’t seem like having your probe get red hot is a feature. However, the probe tip replaces the soldering iron tip, so you are either soldering or measuring, but not both at the same time.

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Close up of a DA14 nixie multimeter

The Nixie Tube Multimeter That Almost Made A Comeback

November 1, 2024 by 3 Comments

In a world of digital monotony, the Avo DA14 digital multimeter, with its vintage nixie tube charm, is a refreshing gem. Recently refurbished by [Thomas Scherrer], this multimeter video review is a blend of nostalgia and tech savvy. The DA14 not only has style, but substance — delivering resistance, current, and voltage measurements that make you wonder why more multimeters didn’t stick with this stylish glow.

As [Thomas] starts by powering up the DA14, we were instantly captivated as the Nixie tubes illuminate in their retro orange. With each twist of the dial, he demonstrates just how intuitive the multimeter is to operate, walking us viewers through each function while giving some extra love to its calibration process—a neat front-panel potentiometer that requires just a touch of finesse to get perfect readings.

But, as with all good tinkering tales, things go downhill when issues with analog inputs and the display pop up. A teardown reveals a beautifully complex inner assembly of transformers, rectifiers, and circuit boards, giving the DA14 its impressive yet fragile structure. When the critical defective display chip is found, hopes for a full repair dim. His story ends without a revival, but if you want to see a similar attempt that did get resurrected – albeit without those nixie digits – take a look at this LCD transplant we covered previously.

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Insides of a multimeter, improved with a custom backlight switch.

Backlight Switch For A Better Multimeter

August 26, 2024 by 28 Comments

Frustrated by his Aldi multimeter’s backlight turning off after just 15 seconds, [Steg Steg] took matters into his own hands. His solution? He added a manual toggle switch to control the backlight, allowing it to stay on as long as needed. He began by disassembling the multimeter—removing the outer bumper and a few screws—to access the backlight, labeled “BL.” He identified the voltage regulator outputting 2.8 V, desoldered the red wire, and extended it to install the switch.

On his first try, he successfully drilled a spot for the SPST switch. To fit the switch into the multimeter’s rubber bumper, he used a circular punch, although his second hole wasn’t as clean as the first. Despite this minor setback, the modification worked perfectly, giving him complete control over his multimeter’s backlight without the original 15-second timeout.

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Fixing A Busted Fluke While Fighting A Wonky Schematic

August 9, 2024 by 16 Comments

Fluke meters have been around for a long, long time. Heck, we’ve got a Fluke 73 that we bought back in 1985 that’s still a daily driver. But just because they’ve been making them forever doesn’t mean they last forever, and getting a secondhand meter back in the game can be a challenge. That’s what [TheHWCave] learned with his revival of a wonky eBay Fluke 25, an effort that holds lessons for anyone in the used Fluke market.

Initial inspection of the meter showed encouragingly few signs of abuse, somewhat remarkable for something built for the military in the early 1980s. A working display allowed a few simple diagnostics revealing that the ammeter functions seemed to work, but not the voltmeter and ohmmeter functions. [TheHWCave]’s teardown revealed a solidly constructed unit with no obvious signs of damage or blown fuses. Thankfully, a service schematic was available online, albeit one with a frustrating lack of detail, confusing test point nomenclature, and contradictory component values.

Despite these hurdles, [TheHWCave] was able to locate the culprit: a bad fusible power resistor. Finding a direct replacement wasn’t easy given the vagaries of the schematic and the age of the instrument, but he managed to track down a close substitute cheap enough to buy in bulk. He searched through 40 units to find the one closest to the listed specs, which got the meter going again. Fixing the bent pin also gave the meter back its continuity beeper, always a mixed blessing.

If you’re in the market for a meter but can’t afford the Fluke name, picking up a busted meter and fixing it up like this might be one way to go. But are they really worth the premium? Well, kinda yes.

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In Praise Of Old Meters

January 12, 2024 by 54 Comments

We are spoiled with multimeters today. Even the cheapest meter you will get these days is almost surely digital with a tremendous input impedance. But a few decades ago, meters were almost always analog affairs. To make a precise measurement, you needed a mirror under the meter to ensure you read the needle correctly. Moreover, a common meter wouldn’t have that high of an input impedance. If you spent more, you could get a VTVM and, later, one that used FETs to provide high input impedance. [Peter AA2VG] just picked up a vintage Micronta FET volt-ohm meter to join some of the other new and old meters in his shack. You can check it out in the video below.

[Peter] already has a Simpson and a more modern Fluke meter. The Simpson, however, doesn’t have a tube or FET amplifier. The Fluke is nice, but there is something about the needle on an analog meter. If you aren’t old enough to remember, the Micronta brand was a Radio Shack label.

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