I traded in my first one (different brand) as this unit was recommended as more reliable and accurate. I’m impressed. It caught a bad capacitor that my previous unit had said was okay.One tip, if a component test fails, check ALL connections and retest. It’s easy to not have things seared properly.

This is a useful little device for the money. It's probably not going to replace your high end ESR meter or other diagnostic equipment, but I've found that it makes identifying things like dead transistors and diodes easy, as well as identifying transistor types, capacitor capacitance, and other things that I've typically done with my digital multimeter (but are more difficult to do that way).I've checked it against my two multimeters and the three devices always agree when it's a pass/fail question, and largely agree on things like capacitance. I will say that this device, even after calibration, always seems to measure capacitance about 5% lower than my multimeters. That's not to say the DMMs are definitely correct, though; it is still possible that this device is closer to correct, but my math tells me there's a 66% chance the DMMs are correct and a 33% chance this component tester is. Anyway, it's not a big deal; 5% is within the tolerance of any *new* capacitor. It does make replacement of "marginal" old capacitors a little trickier to judge, though, since that 5% difference could put a capacitor on one side of its tolerance or the other. I'd probably be a little more conservative (ie. replace drifting capacitors earlier or more often) if solely relying on this tester to judge capacitance.One of the main reasons I wanted this tester was for ESR, and I'm not sure I trust those readings at all. One of the main reasons is that the post-calibration ESR readings I'm getting are wildly different from the pre-calibration readings, but post-calibration it actually seems less believable. Like, it's telling me that all sorts of 40 year old small capacitors have ESR's of like 0.03, even when their capacitance has drifted way out of spec. Many old larger capacitors it reads an ESR for of 0.00! I do notice that when it does its calibration, it performs a resistance test on the leads; I have a feeling it's somehow subtracting this result from its ESR measurement, which may be throwing things off depending on what formula it's actually using.Unfortunately I don't have another ESR tester to check against this device (hence why I bought it) so maybe I do just have caps in all my machines with uncommonly low ESR. I doubt it, though.I do think you can still use it to judge relative ESR and consequently the health of one older cap vs. another, or just the resistance of a newer cap vs. another. Sometimes it'll read like 0.8 for a cap and then 0.3 for an otherwise identical cap; I'm guessing that the first cap probably does have an ESR about 2.5 times the second, but who knows what it actually is. But the second cap is probably in better shape, so it's still useful info even if the actual number is incorrect.I do totally get what some people say about the flimsy leads this thing comes with, however if you're a little bit careful with them they should last long enough. I've done probably 100 measurements with them so far and while I did yank one in the wrong direction once and bent the pin, it was easy enough to bend back. Otherwise, the leads are still all fine. I'm sure you can buy replacements for cheap if you need to.Overall, definitely not a professional level diagnostic device, but for a hobbyist, it'll help you out and make certain things easier. And if nothing else, it can act as a check on other devices you might have (and vice versa). Often I will get readings on my DMMs that seem kind of implausible, so for less than twenty bucks, it's not a bad idea to just have something else to verify those results, even if they're just close.

Tested with several transistors, capacitors, diodes and resistors. Every time the tester responded perfectly with very slight variations within 5-10% from the datasheet values.

PROS: The tester itself is nice. Quickly tests transistors, resistors, capacitors, etc. Results with resistors and capacitors seem good, though I don't have a different reference. Identifies base, collector, emitter reliably.CONS: The test leads do fall apart after a while. One pin broke off. It's been 6 months of light use, but maybe that is expected. Whatever. (Just realized that I can plug TO-92 transistors directly into the unit - no wires required.)WORSE: The transistor Vf results are very inconsistent. Tested one transistor.With the test leads. Vf=1.2V.Plug directly into unit (no test leads) Vf=0.987V.Switch battery (still no test leads): Vf=0.782V.Can't really rely on this measurement.

I figure the device itself could be (likely is) good, but the test contacts are so unreliable that getting a good read is a matter of chance. Not what you want in a component tester. Going to return this and hope a different manufacturer has better QA processes.For starters, not related to the contacts, it mis-reports the battery voltage. When measuring the battery voltage independently while the device was operating, the DMM shows 8.6V (with the battery showing 9.4 unloaded). The tester says the battery is OK at 7.5V. That aside, the battery compartment is just a little too small which makes it hard to open or close, and uses the dreaded 9V clip-on-a-wire which is always good for some cursing when it gets time to replace the battery.The ZIF socket is separate and gets inserted into the 4x8 header on the front. The fit is not what I would call confidence inspiring.I took a few known working components and inserted them. An LED got correctly identified the first time. I moved it to different contacts with the same numbers and now it shows as a capacitor. Moved it to different contact numbers and it comes up as "no or bad". A 2N7000 MOSFET was sometimes identified as 2 diodes, a few times correctly, sometimes as "no or bad".