How to Use a Fluke Multimeter to Test Voltage on Sartorius Equipment: An Emergency Checklist

It's 4:30 p.m. on a Thursday. You have a release batch scheduled for 8 a.m., and the Sartorius checkweigher on the line is dead. Or the Sartorius electronic pipette won't charge, and the analyst has 24 samples to pipette before the end of the shift. You have two options: call for emergency service and hope someone answers, or spend 20 minutes checking the one thing that fails most often—the power input.

This checklist is for that exact moment. I work as a service coordinator for lab equipment, and I've handled more than 200 rush orders over the past nine years, including same-day turnarounds for QC labs where a missed deadline would have meant a contract penalty. The steps below won't fix every failure. But they will tell you—quickly—whether the problem is in the power supply, the cable, or the instrument itself.

You'll need a good multimeter. In our service group, the two we keep reaching for are the Fluke 87V Max true-rms digital multimeter and the older Fluke 189 true rms multimeter (i.e., the one that's been discontinued but still earns its place in the drawer). Both are true-rms, so they handle distorted waveforms correctly—which matters with modern switching power supplies.

Step 1: Confirm You're Looking at a Power Failure, Not a Load-Cell Failure

From the outside, a checkweigher that won't turn on looks like a load-cell or electronics failure. The reality is that the root cause is usually upstream: an adapter that stopped outputting, a damaged cable, or a loose connector. The same goes for electronic pipettes that won't charge. If the charging dock isn't getting power, no amount of pairing or resetting will help.

People assume a power failure means the instrument is dead. Actually, the opposite is common: the instrument is fine, and a relatively cheap adapter is the problem. That's why step one is to resist the urge to open anything internal. Get your multimeter and verify the basics first.

When I'm triaging a rush order, I ask three questions in order: How much time do we have? Can we get a replacement before the deadline? What's the risk of making it worse? Testing voltage addresses all three—it takes minutes, not days.

Step 2: Get the Right Meter—and Check the Meter Itself

Before you test anything, confirm your meter is trustworthy. According to Fluke's published specifications (accessed January 2025), the 87V Max is rated CAT III 1000V / CAT IV 600V. That's overkill for a 12V or 24V wall adapter, but the safety margin matters if you're also troubleshooting a balance's main supply. The Fluke 189, if you have one in the drawer, is still a true-rms workhorse. If I remember correctly, the 189's input rating is also CAT III 1000V, but don't quote me on that—just check the yellow label on the back.

Then do the boring part: verify your test leads. In my first year, I made the classic rookie mistake of testing a perfectly good power supply with a lead that had an intermittent break. It looked like 0 V on the display. I ordered a $250 replacement adapter, and the original magically worked once I wiggled the lead. Now, every emergency call starts with a 5-second continuity check of both leads.

Step 3: Test the Power Supply Output (Open Circuit)

Disconnect the Sartorius instrument from its power supply. You're measuring the adapter alone, not the instrument's input circuit.

1. Set the meter to DC volts. Most lab instrument adapters output DC—12V or 24V are common. On the 87V Max, auto-range handles this; on an older 189 in manual mode, select a range just above the expected voltage.
2. Put the black probe on the center pin of the barrel connector and the red probe on the outer sleeve. (The polarity doesn't matter for this check—you'll just see a negative reading if you have it reversed.)
3. Plug the adapter into the wall and read the display after 30 seconds.

You're looking for a stable value close to the label on the adapter. If the label says 24V DC and you see 4V, 0V, or a value that drifts around, the adapter is failing. If the reading is clean, move to Step 4.

One caveat: some adapters only output voltage when they see a load. At least, that's been my experience with the smaller Sartorius power supplies—not every adapter behaves the same. I want to say that's rare for checkweighers and pipette chargers, but don't quote me on that—if the connector has more than two pins, look up the manufacturer's pinout before you assume a no-load reading is a fault.

Step 4: Test the Instrument Side (The Step Everyone Skips)

This is the one I wish every customer would do. Most people stop at the wall adapter. But the connector that plugs into the back of a balance or the base of an electronic pipette charger can fail internally, especially if it's been pulled hard or wrapped tightly. A cable with broken strands will pass a quick visual check but fail when you flex it.

With the power supply unplugged from the wall, inspect the instrument's input socket for bent pins or debris. Then plug the adapter into the wall and connect it to the instrument. Use your multimeter to back-probe the input terminals where the cable enters the instrument—if you can access them without opening the case. If you measure the rated voltage at the adapter output but nothing at the instrument input, the problem is the cable or connector. Replace the cable before ordering a service visit.

If you can't back-probe safely, don't force it. The goal isn't to turn every lab manager into a bench technician; it's to rule out the cheap fix before spending money on an emergency call. Per Sartorius support documentation, the instrument's rating label is the source of truth for voltage and current requirements—not the adapter label.

Step 5: Decide: Replace, Repair, or Call for Help

By now you have one of three scenarios:

• No voltage at the adapter output: replace the adapter. This is the best outcome. Order an OEM or manufacturer-recommended replacement—not a random third-party brick. A mislabeled supply can damage the instrument's board.
• Good voltage at the adapter, none at the instrument input: replace the cable or connector. If it's user-serviceable, this is a 15-minute fix. If not, a service person can do it quickly.
• Voltage present at the instrument input, but it still won't power on: you're likely looking at an internal PCB, load cell, or battery issue. That's the point where you call Sartorius service (or your local authorized provider) and get it on the schedule.

It's tempting to skip the cable test and immediately order a service visit. I get it—when a deadline is on the line, time feels more valuable than money. But based on our internal data from 200+ rush jobs, roughly 30% of no-power calls end up being a simple adapter or cable issue. Spending 15 minutes with a meter can save you the cost of an emergency service call (which, on our job records, is often 25–50% more than standard service rates).

Notes From the Field: What I've Learned the Hard Way

First, don't assume a reading is correct just because the display has digits. A true-rms reading is only as good as the meter's accuracy and your technique. If you're asking how to use a Fluke multimeter to test voltage, start with a known-good source (like a wall outlet) before you trust the reading on a questionable adapter.

Second, don't skip calibration after a repair. A Sartorius checkweigher or analytical balance is a measuring instrument. If you disconnect the power supply or handle the instrument during troubleshooting, the internal reference isn't automatically compromised—but the moment you suspect any impact, do a performance check with certified weights before putting it back into a release decision. That's not a manufacturer requirement meant to sell calibration services; it's about the integrity of your data.

Third, the industry has evolved. In 2020, the default reaction to a failed checkweigher was to call a field service engineer and wait. By 2025, with a good multimeter, a phone camera, and online support documentation, a lab supervisor can safely diagnose the top three causes of no-power failures. What was best practice in 2020 doesn't necessarily apply now. But the fundamentals haven't changed: get the right training, use the right tool, and don't take shortcuts around live electricity.

That said, I should note: if you're not comfortable working around electrical connections, this checklist isn't a substitute for training. The most dangerous step in any emergency repair is the one where you assume something is dead when it isn't. A Fluke 87V Max gives you a clear picture of voltage, but it doesn't replace judgment.

In March 2024, a client called at 4 p.m. because their Sartorius checkweigher was down and they had a batch release at 8 a.m. Standard repair turnaround was five days. We ran these diagnostic steps over the phone, found the adapter outputting 1.2V instead of 24V, and rushed a replacement adapter to them by 6 a.m. The cost of the adapter and overnight shipping was about $180. The alternative—an emergency service call plus downtime—would have blown past $2,000. Missing that deadline would have meant a $50,000 penalty clause. It didn't come to that, but only because someone was willing to test voltage before swapping circuit boards.

So if your Sartorius electronic pipette won't charge, or your checkweigher gives you a blank display, take a breath. Grab a true-rms multimeter, work through the checklist, and let the voltage readings tell you where the fault is. It's fast, it's cheap, and it's the difference between an emergency and just another Tuesday.