The DT9205A multimeter offers you several amplitudes of measurement with which to test electrical components for voltage, resistance or continuity. You can measure several different magnitudes of these quantities by adjusting the dial on the surface of the multimeter. The two most common uses for a multimeter are to test voltage and resistance.
The DT830D is a digital multimeter made in China. It is capable of measuring voltage, current, resistance, transistor, diode, and has a signal generator function. However, you should be aware that it cannot measure capacitor values. There are many branded versions of this meter all with the same model number. I managed to find UNI-T, DOSS, Fuke, Haoyue, Nora, and Sunwa versions that were all identical to the one shown in this article and based on the same 830 series chip. This meter has the ICL7106 Chip on Board (COB) package and the accuracy figures are very much the same as those of the DT830B.
This meter does not come with a service manual, or instructions of any kind, and instead, the accuracy figures are on the back of the box. If you need more information regarding accuracy then please refer to the DT830B article. If you need a service manual, then I have a section on the ICL7106, which should be very useful because it has a multimeter circuit.
Please note that the model specification, and price, may change over time. The contents offering (such as box, manual, probes) may also differ between sellers; therefore it is advisable to search for the best offer currently available on auction sites.
Review
I decided to get this meter for three reasons; it has a very bright attractive colour, it has a signal generator function, and it was only £2.50 including postage! I tested the voltage measurements up to 20 V and found them to be accurate. The resistance measurements up to 2 MΩ were also good enough for hobby use, and the signal generator function also worked fine. For the semiconductor tests, the transistor test function was adequate, and the diode test accurately measured the forward voltage drop!
The LCD is nice and clear and the segments are thick enough to be legible. The contrast appears to be much better than the earlier meters. This particular one also has an HV symbol, and a negative symbol.
This meter had the CE mark; however, if I remember correctly, this is a self-certification logo and does not constitute any type of independent formal testing.
Bad Points: You should be aware of some minor cosmetic issues. The probe plugs did not fit properly or sit straight. The front sticker for the switch was poorly stuck with an uneven finish.
LCD Contrast - Excellent
As you can see, the LCD contrast is wonderful! If you have a digital multimeter that was over five years old, then the good news is that they have made huge advances in LCD technology. There are very few LCD manufacturers, and therefore some of the high-end meters will also have the same display.
Fuse: Un-Fused Shunts
For the current measurement, the instructions on the back cover indicate that there is a fuse protection. However, if you look inside, there is no fuse! A fuse is a very important safety component that should be included in all meters. Even some of the cheapest budget-end designs have them. Un-fused shunts mean that your meter has no way to protect itself from over-current situations. In such an eventuality, the PCB trace will burn, or the main chip damaged, and therefore your meter will not last very long.
Since there is no fuse protection, the maximum current ratings may not be accurate either. On the meter, there is a marking indicating '200 mA max'. It made me wonder whether this was the rating of the PCB trace. This meter could get damaged if the setting is on 200 mA, and you pass 1 ampere through it by mistake. You will therefore have to be very careful when you are measuring current, or best not to use it at all for current measurement.
Probe Wire Resistance
The probe wires show a resistance of 0.5 Ω and the quality appears to be the same as the earlier designs in the DT830 series. If you decide to use this meter, you will need better probes, otherwise do not use the 10 A option to measure current.
Even though mine came sealed and brand new, the probes were making intermittent connections. I contacted the sellers and they were happy to provide replacement probes.
1000 V Arc Test
Although this meter has 200 V, 750 V, and 1000 V settings, I would not use this meter for any kind of high voltages in this range.
For me to use it for higher voltages, I would require serious assurances, including arc test reports, and some heavyweight British safety certification logos before I would even consider it. The European CE mark on its own is meaningless to me.
The Sniff Test
I recently had an email from my friend Avid -- a German Wikipedian -- who said that when he smelt the plastic he was seeing the women...
He was convinced that the Chinese were mixing chemicals into the plastic to make him see them... He even showed me photographs of his extensive meter collection that he used for sniffing purposes...
I sniffed this one and I am sorry to report, Avid, that I did not see any women... :-)
Conclusion
Based on the excellent DT830B chip, this meter has the same accuracy figures, and provides adequate readings. The plug and socket system on the DT830B seemed slightly better than on this. However, this information comes from a sample of ONE, which I bought. If they have made better batches, then you might get something completely different, hopefully better. The factory is always making improvements to their production line, and chances are that they may have improved the design. In this case, it would be worth buying!
For non-critical and hobby use up to 20 V and 200 mA, this might be fine - but as Scotty always says -- 'I cannot guarantee it though!' On the plus side, it has a nice cheerful bright colour, and for £2.50 including postage, it is a bargain! I would not be too surprised if this meter ended up selling in pound stores, in which case I would probably take five.
This article continues, and in the following sections, you can see the inside circuit, case, selector switch, and more.
This Article Continues...
DT830D Digital MultimeterDT830D Circuit Board
DT830D Digital Multimeter Repair and Fuse
DT830D How to Use Instructions
DT830D Box and Packaging
DT830D Design Review
DT830D Manual
DT830D Battery Replacement
Introduction
Every fixer should know their way around a multimeter, which has just north of a zillion uses for testing electronic components and circuits. Follow along to master the three most basic functions of a multimeter.
No parts specified.
- A continuity test tells us whether two things are electrically connected: if something is continuous, an electric current can flow freely from one end to the other.
- If there's no continuity, it means there is a break somewhere in the circuit. This could indicate anything from a blown fuse or bad solder joint to an incorrectly wired circuit.
- Continuity is one of the most useful tests for electronics repair.
- To begin, make sure no current is running through the circuit or component you want to test. Switch it off, unplug it from the wall, and remove any batteries.
- Plug the black probe into the COM port on your multimeter.
- Plug the red probe into the VΩmA port.
- Switch on your multimeter, and set the dial to continuity mode (indicated by an icon that looks like a sound wave).
- Not all multimeters have a dedicated continuity mode. If yours doesn’t, that’s okay! Skip to Step 6 for an alternate way to perform a continuity test.
- The multimeter tests continuity by sending a little current through one probe, and checking whether the other probe receives it.
- If the probes are connected—either by a continuous circuit, or by touching each other directly—the test current flows through. The screen displays a value of zero (or near zero), and the multimeter beeps. Continuity!
- If the test current isn't detected, it means there's no continuity. The screen will display 1 or OL (open loop).
- To complete your continuity test, place one probe at each end of the circuit or component you want to test.
- As before, if your circuit is continuous, the screen displays a value of zero (or near zero), and the multimeter beeps.
- If the screen displays 1 or OL (open loop), there's no continuity—that is, there's no path for electric current to flow from one probe to the other.
- Continuity is non-directional, meaning it doesn't matter which probe goes where. But there are exceptions—for instance, if there's a diode in your circuit. A diode is like a one-way valve for electricity, meaning it will show continuity in one direction, but not in the other.
- If your multimeter doesn't have a dedicated continuity test mode, you can still perform a continuity test.
- Turn the dial to the lowest setting in the resistance mode.
- Resistance is measured in ohms, indicated by the symbol Ω.
- In this mode, the multimeter sends a little current through one probe, and measures what (if anything) is received by the other probe.
- If the probes are connected—either by a continuous circuit, or by touching each other directly—the test current flows through. The screen displays a value of zero (or near zero—in this case, 0.8). Very low resistance is another way of saying that we have continuity.
- If no current is detected, it means there's no continuity. The screen will display 1 or OL (open loop).
- To complete your continuity test, place one probe at each end of the circuit or component you want to test.
- It doesn't matter which probe goes where; continuity is non-directional.
- As before, if your circuit is continuous, the screen displays a value of zero (or near zero).
- If the screen displays 1 or OL (open loop), there's no continuity—that is, there's no path for electric current to flow from one probe to the other.
- Plug the black probe into the COM port on your multimeter.
- Plug the red probe into the VΩmA port.
- Switch on your multimeter, and set the dial to DC voltage mode (indicated by a V with a straight line, or the symbol ⎓).
- Virtually all consumer electronic devices run on DC voltage. AC voltage—the kind that runs through the lines to your house—is considerably more dangerous, and beyond the scope of this guide.
- Most multimeters are not autoranging, meaning you will need to set the correct range for the voltage you expect to measure.
- Each setting on the dial lists the maximum voltage it can measure. So for example, if you expect to measure more than 2 volts but less than 20, use the 20 volt setting.
- If you're not sure, start with the highest setting.
- Place the red probe on the positive terminal, and the black probe on the negative terminal.
- If your range was set too high, you may not get a very accurate reading. Here the multimeter reads 9 volts. That's fine, but we can turn the dial to a lower range to get a better reading.
- If you set the range too low, the multimeter simply reads 1 or OL, indicating that it is overloaded or out of range. This won't hurt the multimeter, but we need to set the dial to a higher range.
- With the range set correctly, we get a reading of 9.42 volts.
- Reversing the probes won't do any harm; it just gives us a negative reading.
- To begin, make sure no current is running through the circuit or component you want to test. Switch it off, unplug it from the wall, and remove any batteries.
- Remember that you'll be testing the resistance of the entire circuit. If you want to test an individual component such as a resistor, test it by itself—not with it soldered in place!
- Plug the black probe into the COM port on your multimeter.
- Plug the red probe into the VΩmA port.
- Switch on your multimeter, and set the dial to resistance mode.
- Resistance is measured in ohms, indicated by the Ω symbol.
- Most multimeters are not autoranging, meaning you will need to set the correct range for the resistance you expect to measure. If you're not sure, start with the highest setting.
- Place one probe at each end of the circuit or component you want to test.
- It doesn't matter which probe goes where; resistance is non-directional.
- If your multimeter reads close to zero, the range is set too high for a good measurement. Turn the dial to a lower setting.
- If you set the range too low, the multimeter simply reads 1 or OL, indicating that it is overloaded or out of range. This won't hurt the multimeter, but we need to set the dial to a higher range.
- The other possibility is that the circuit or component you are testing doesn't have continuity—that is, it has infinite resistance. A non continuous circuit will always read 1 or OL on a resistance test.
- With the multimeter set to a usable range, we get a reading of 1.04k ohms.
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