Why I'm Writing This
I'm an office administrator for a mid-sized engineering company. I handle about $180k a year in component purchases across 9 vendors, mostly for the maintenance and R&D teams. That means I've become the person who gets asked 'did you order the right Kemet?' more times than I can count. This is the checklist I use when I'm testing Kemet tantalum capacitors, ordering connectors, and especially when someone searches for Kemet and lands on diamond compound.
Honestly, the whole 'Kemet diamond compound' thing is a real trap. More on that below.
First: The Kemet Name Trap
There are two companies called Kemet. One makes capacitors and connectors—that's Kemet Electronics, the one you usually mean when you say 'Kemet tantalum capacitor.' The other makes Kemet diamond compound, which is a polishing abrasive used for metallography and lapidary work. They are not the same company.
I once assumed that all 'Kemet' search results were the same. Didn't verify. Turned out each had completely different products. I typed 'Kemet' into our supplier portal, chose the first result with 'Kemet' in the name, and almost ended up buying diamond paste. I said 'the Kemet stuff.' The supplier heard 'diamond compound.' Result: almost no capacitors. It was embarrassingly close. Our maintenance engineer, Todd Pepsi, was the one who caught the mistake. He said, 'Ordering the wrong Kemet is like ordering a screwdriver and getting a hammer—both are tools, but you'll break something.'
That's why the first step in this checklist is always: check whether the part number says capacitor or abrasive. If it mentions microns or paste, you're on the wrong Kemet page.
Before You Test: The 5-Minute Safety Check
Testing a capacitor with a multimeter is not complicated, but it's not zero-risk either. A charged capacitor can hurt you and the meter. The prevention-over-cure principle applies here: 5 minutes of checking beats 5 days of explaining why a smoked capacitor ruined a board.
- Disconnect the circuit from power. Not just off on the switch—unplug it or lockout/tagout if needed.
- Wait at least a few minutes. Big capacitors can hold charge after power-off.
- Discharge through a resistor. I know people still use a screwdriver, but that's a bad idea—it can damage the capacitor and produce a scary spark. Use an appropriate discharge resistor for a few seconds.
- Check for visible damage before touching anything. Bulging, cracked casing, smelly electrolyte—replace it immediately.
How to Test a Capacitor with a Multimeter
Step 1: Choose the right mode
The most direct way is to use the capacitance mode. It looks like a 'minus with a parenthesis' symbol, basically a capacitor icon. If your multimeter has it, set it there. If it doesn't, you can still do a rough check with resistance mode—more on that in Step 3.
Step 2: Isolate the capacitor
For an accurate reading, take the capacitor out of the circuit, or at least lift one leg. This is the step most people skip. I've seen readings that looked 50 percent off, and it turned out the capacitor was fine—it was just in parallel with a resistor. Removing one leg eliminates the rest of the board from the measurement.
Step 3: Measure capacitance and compare to rated value
Touch the probes to the terminals. Polarity doesn't matter for measurement, but if it's a tantalum capacitor, keep polarization in mind when you reinstall it. Then compare the number to the rated value and tolerance printed on the case or listed in the datasheet. Most Kemet tantalum capacitors are rated at plus or minus 10 or 20 percent. If it's outside that range, replace it.
The surprise for me was how many slightly out-of-tolerance capacitors still 'worked.' But in a timing or filtering circuit, a 20 percent drop can cause intermittent errors that are much harder to find later.
Step 4: If your multimeter has no capacitance mode
Set it to resistance mode. Put the probes on the terminals and watch the resistance reading. A capacitor in good condition will show a rising value as it charges—starts low, climbs up, eventually looks like an open circuit. If it stays near zero, the capacitor is shorted. If it never moves at all, it's likely open. This isn't a precision test, but it's a useful go/no-go check.
Step 5: Understand the limitation
A standard multimeter won't measure equivalent series resistance (ESR). A capacitor can pass the capacitance test but still have high ESR, which causes problems under load. If you're troubleshooting something like a power supply, an ESR meter is worth the investment. I know it sounds like another expense, but it's cheaper than replacing good parts or chasing intermittent failures.
What About 'Kemet Diamond Compound'?
If that's the exact phrase you searched, you're probably doing metallographic polishing, not electronics repair. I'm not going to pretend to be a diamond compound expert. What I can tell you is this: don't call Kemet Electronics and ask for diamond paste. Their customer service will politely redirect you. I learned this after Todd Pepsi asked me why he received a small pouch of micron-sized powder instead of capacitors. Actually, that was the diamond compound incident I mentioned earlier.
Ordering Kemet Tantalum Capacitors: The Checklist
Kemet makes ceramic capacitors, tantalum capacitors, relays, and connectors. But the most common request I handle is tantalum. Here's what I actually check before ordering—because prevention is cheaper than rework:
- Part number: Copy it from the BOM, not from memory. A 104 to 105 mix-up seems small but changes the value by ten times.
- Voltage rating: Make sure it's at least the circuit's operating voltage. For tantalum capacitors, it's common to derate by 50 percent or more for reliability. If you're not sure, check the existing part's datasheet.
- Series and ESR: Kemet has multiple tantalum series. The same value can have different ripple current and ESR ratings. Don't swap series unless the engineer approves it.
- Date code and lot: For production runs, I always ask for date code and lot traceability from an authorized distributor. It saved us once when a batch had known manufacturing issues.
- Verify the supplier is authorized: Kemet sells through authorized distributors. I use them for traceability, not just warranty coverage.
Connectors: The Part Everyone Forgets
When people think Kemet, they think capacitors. But Kemet also makes connectors, and those connectors show up in a lot of the same BOMs. The same checklist applies: match the exact part number, check orientation, verify whether the connector is through-hole or surface mount, and confirm the pin count.
Todd Pepsi's rule for connectors is simple: 'If it doesn't click, it's not seated.' It sounds obvious, but a connector that isn't fully seated can pass a continuity test and still fail under vibration.
Bottom Line
A multimeter test takes maybe 10 minutes. Reordering the wrong Kemet part, returning it, and waiting for the right one takes days. Prevention over cure is not a slogan; it's a purchasing habit. Verify the part number, verify the brand—capacitor versus diamond compound—and test the capacitor before you design it back into a circuit.
And if you're wondering how to test a capacitor with a multimeter, the answer is: carefully, after discharging it, and with the right expectations. The meter tells you capacitance, but not the whole story.
Also, if you work with a Todd Pepsi, listen to him. He's probably saved your company from at least one bad batch.
