Review of the DY294 Digital Transistor Tester

Review of the DY294 Digital Transistor Tester-Part 1

1

Last week i was busy with the repair course and holiday and finally today i could review the meter. The DY294 Digital Transistor Tester is using 4 pcs of AA batteries and and this tester can be used to test on many type of components. Select to the range as shown in the photo below and you will know the total voltage of the internal batteries:

Below are the result of certain components that i have tested and i will proceed to provide more information on other components in part 2. Voltage Regulator IC: Just insert the IC to the respective point (point 1, 2 and 3) and press the TEST button and see the result



Insulation Test on Non Polar Cap: There is only one range for you to select to test the non polar cap- 1000v. The 200 volt produce no result when test on non polar cap. Set to 1000v to test on non polar cap that have working voltage of 1kv and above. For a good cap, it will show approximately 1500v and if the non polar cap insulation have problem, it will show a very low voltage from 60 to about 300 volt. This test have similar function like an insulation tester.



If you need to test on non polar cap that have working voltages that is less than 1000v then you may need to add a resistor in parallel so that the insulation of the non polar would not fail when you pump in the 1000volt to the cap. As for the resistor value you have to find it on your own because the manual does not comes with it. In the photo below, i found that the resistor of 560kOhm is suitable to test on a non polar cap that have 250 volt working voltage. If you use a lower ohm value the non polar cap insulation may breakdown. From the same photo you could see that the max voltage only hit 231 volt. If this non polar cap insulation have problem, the value could be less than 100volt.

Testing on Electrolytic Capacitor: For your information, this meter is not design to test on the ESR or the capacitance value of e-caps. It test just the same way for a non polar cap. Just insert the e-cap into the respective section and select 200 VDC as shown in the photo and press the Test button. The LCD display will show the capacitor is charging and it will charge up to 200vdc-make sure that you are testing a cap that have working voltage higher than 200 volt. The disadvantage of this test is you have to wait for the cap to charge up.



The advantage of this meter over insulation tester is that it can be used to test on e-caps that have lower working voltage like 16 volt, 25 volt, 50 volts and etc. Just make sure that when you want to test a lower voltage of capacitor, the charging voltage should not exceed the working voltage. That means if you want to test a 16 volt cap, make sure the charging voltage would not exceed 16 volt. If there is a problem with the cap, there would be no charging or the charging would just stay at one value for example it stays at 8 volt and stop. I found that this tester consume lots of current especially testing on the capacitor. If possible get a 6 vdc (2 amp) power adapter to power up this meter. In the long run, you could save the cost of buying batteries. Another thing is that if the batteries voltage is lower than 5.7 volt, i found that the test result would not be accurate especially testing on the non polar caps. Stay tune for more testing result in Part 2.

Review of the DY294 Digital Transistor Tester-Part 2 Hope you have enjoyed part 1 test result of this DY294 Digital Transistor Tester and below is the part 2 test result: Use as a DC voltage signal source: This meter produce over 240 and 1000 volt and you can use this voltages as a Dc signal source for troubleshooting and etc.



Testing LED: Certain types of LED can’t be test using analog meter like the one use in the Blue ESR meter. However this meter can be used to test on many different types of LED. Just set the meter to few different ranges and you could see the LED will light and the intensity of the light is depends on which range that you have selected.

Testing Varistor: This meter can be used to test on voltage value of a Varistor. In the photo below, the Varistor have a rating of 471 volt and this meter reads 472 volt which is quite accurate. A bad Varistor will not show the exact voltage value.



Testing Neon Lamp: Don’t be surprise that this meter can be used to check on the Neon Lamp. Just connect the Neon Lamp and select 2 Amp range and you could see that the neon lamp will light up.

Testing Ultra Fast Recovery And Schottky Diode Forward voltage drop: The result can be seen from the photos below:





Testing Ultra Fast Recovery and Schottky Diode Reverse Breakdown voltage: The test result can be seen from the below photos:







Testing Zener Diode Forward Voltage Drop: Test result can be seen from the photos below:

Testing Zener Diode Breakdown Voltage: I found that the test result for certain zener diode voltage value was not really exact because zener diode just like other components have tolerance. See the photos below especially testing the 15 volt zener diode. it reads only 14.3 volt:

From these two parts of testing it seems that this meter is a winner as it can test so many types of electronic components. Don’t miss out on part 3 as there will be more information to be revealed soon.

Review of the DY294 Digital Transistor Tester-Part 3 Here is the part 3 of the review of the DY294 Digital Transistor Tester: Testing FET breakdown voltage: Every transistor have a breakdown voltage and this meter can be used to test on the Nchannel and the P-channel Mosfet transistor. The test result were higher than the original value printed on the transistor spec. Please refer to the photos below for more information:











Testing SCR and Triac: I found that the test result for SCR and Triac breakdown voltage were way out as compare to the device’s spec. This happen most probably because there is no gate signal present at the gate pin. Testing Transistor Dc Current Gain hfe: Sometimes a transistor can be tested okay with a normal meter but because of there is changes in the hfe value of the transistor, that particular transistor may not work when under full load. So it is equally important to test the hfe value as compare to just finding out the base, collector and emitter pin of the transistor. Below are the photos of the test result;





For your information, if the Horizontal Output Transistor (HOT) have a built in damper diode then this tester can’t test out the hfe value. It will just show “0.00” result. What About Testing Other Transistor Parameter? Well , the test result are more or less the same as testing the FET breakdown voltage. Just do not expect it to be exactly the same with the transistor specification downloaded from the internet. Comment about this meter?

The disadvantage of this meter is that it does not have a proper probes to hold the components and you have to insert the components into the desire socket and this can cause the internal socket to loosen easily. Second, external 6 volt 2 amp dc power supply may be needed to test on high power transistor. Third, the manual provided especially the connection of the components was quite blur. Since this meter is quite cheap and have the ability to test so many components, you have nothing to loose to own one. Thank You Jestine Yong