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electronic_component_testing_cheatsheet [2022/02/08 12:12]
sausage [Relays]
electronic_component_testing_cheatsheet [2022/03/02 22:38] (current)
sausage [Conclusion]
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 ====== Electronic Component Testing Cheatsheet ====== ====== Electronic Component Testing Cheatsheet ======
  
-When doing a repair job, it's nice to have a handy testing cheatsheet for a range of electronic components. So far I haven'​t found one, so I created my own here which covers everything from very basic fuses and resistors to MOSFETs, even Gas Arrestor Tubes. All using a multimeter and other tools. I've tried to cater for absolute beginners to intermediate hobbyists.+When doing a repair job, it's nice to have a handy testing cheatsheet for a range of electronic components. So far I haven'​t found one, so I created my own here which covers everything from very basic fuses and resistors to MOSFETs. All using a multimeter and other tools. I've tried to cater for absolute beginners to intermediate hobbyists.
  
-My favourite tools are the Anmeg AN8009 ​mutimeter ​and GM 328 component tester. You can find them both on Aliexpress.+My favourite tools are the [[https://​www.aliexpress.com/​wholesale?​SearchText=AN8009 ​| Aneng AN8009 multimeter]] ​and [[https://​www.aliexpress.com/​wholesale?​SearchText=gm328 | GM 328 component tester]]. You can find them both on Aliexpress.
  
 {{:​component-cheatsheet:​anmeg-an8009.jpg?​direct&​200|}}{{:​component-cheatsheet:​gm328.jpg?​direct&​300|}} {{:​component-cheatsheet:​anmeg-an8009.jpg?​direct&​200|}}{{:​component-cheatsheet:​gm328.jpg?​direct&​300|}}
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 An OL reading means ''​open line''​ or ''​broken connection''​. No current will pass, so it's a bad resistor. An OL reading means ''​open line''​ or ''​broken connection''​. No current will pass, so it's a bad resistor.
  
-An almost 0Ω reading is a short. Of course, there are very low value resistors, for example BROWN BLACK SILVER GOLD, totaling ​0.02Ω, so always check the resistor chart to be sure.+An almost 0Ω reading is a short. Of course, there are very low value resistors, for example BROWN BLACK SILVER GOLD, totalling ​0.02Ω, so always check the resistor chart to be sure.
  
 ---- ----
  
-===== Switches ​(TODO) ​=====+===== Switches =====
  
-You can never under-rate the testing of a switch. Switches can breakit'​s ​continutity ​can flucuate. A switch can be normally open (the most common type) or normally closed. ​+You can never under-rate the testing of a switch. Switches can breakit'​s ​continuity ​can fluctuate. A switch can be ''​normally open'' ​(the most common type) or ''​normally closed''​.  
 + 
 +{{ :​component-cheatsheet:​switch-testing.png?​direct&​400 |}}
  
 The continuity tester on your multimeter is the mode to use. The continuity tester on your multimeter is the mode to use.
  
-An interest ​break in a recent dishwasher repair, I had a microswitch that would click when pressed... it sounded like it was activated, but unless you pressed it further, there was no continutity. Needed replacing.+  - If it's a normally open switch, ensure there is only continuity when it is pressed. 
 +  - If it's a normally closed switch, ensure there only continuity when it is not pressed. 
 + 
 +An example of an interesting switch ​break [[vulcan_dishlex_milano_dishwasher_repair|in a recent dishwasher repair]]: with a microswitch that would click when pressed... it sounded like it was activated, but unless you pressed it further, there was no continuity. Needed replacing.
  
 ---- ----
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 For capacitance tests, always best to test off the PCB if possible, though you can be lucky on the board. Use the capacitor test on your multimeter if you have one, and if you get the expected reading in nano-farads or micro-farads,​ then all well and good.  For capacitance tests, always best to test off the PCB if possible, though you can be lucky on the board. Use the capacitor test on your multimeter if you have one, and if you get the expected reading in nano-farads or micro-farads,​ then all well and good. 
  
-For ceramic caps on the board, sometimes I like to test these using a continuity test. Placing the probes at either end, there will be a short beep at the cap charges, and will stop when it reaches capacity. Swap the leads around and it will beep again until it reaches capacity.+For ceramic caps on the board, sometimes I like to test these using a continuity test. Placing the probes at either end, there will be a short beep as the cap charges, and will stop when it reaches capacity. Swap the leads around and it will beep again until it reaches capacity.
  
 If you get an unexpected readings for any cap, remove from the board and try again after discharging it.  If you get an unexpected readings for any cap, remove from the board and try again after discharging it. 
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 You can also test for a short by using the resistance setting. If you get a very low reading around 0.01Ω etc in either direction, you have a shorted out diode. You can also test for a short by using the resistance setting. If you get a very low reading around 0.01Ω etc in either direction, you have a shorted out diode.
  
-Testing LEDs (which are diodes too) is fun with a multimeter because you can see them light up in the correct ​direction.+{{ :​component-cheatsheet:​led-testing.png?​direct |}} 
 + 
 +Testing LEDs (which are diodes too) is fun with a multimeter because you can see them light up with the correct ​orientation.
  
 Sometimes you can get false positives with parallel components, so remove the diode from the board to test if in doubt. Sometimes you can get false positives with parallel components, so remove the diode from the board to test if in doubt.
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 For MOSFETs, you'll need to search for your part to identify which pins are the Gate, Drain and Source pins. For MOSFETs, you'll need to search for your part to identify which pins are the Gate, Drain and Source pins.
  
-Place you finger on all three pins for a moment to de-charge the MOSFET. MOSFETs have a little capacitance in them which is handy for the test. +Remove from the PCB and place your finger on all three pins for a moment to de-charge the MOSFET. MOSFETs have a little capacitance in them which is handy for the test. 
  
 Switch to diode setting. Switch to diode setting.
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 ---- ----
  
-===== Gas Glass Surge Arrestors / Gas Glass Discharge Tubes ===== 
  
-{{:​component-cheatsheet:​gas-surge-testing.png?​direct |}}I include this because they look like a cross between a zener diode and the colour bands of a resistor. Little is written about them, but they can be located in some switch mode power supplies. ​ 
- 
-Switch to continuity mode. 
- 
-Connect the probe at both ends. 
- 
-If you get a continuity beep then the tube is good. Otherwise it is bad. 
- 
----- 
  
 ===== Thermistors =====  ===== Thermistors ===== 
  
 These are resistors that vary their value according to the temperature. The ohms value can go up or down when the temperature increases. These are resistors that vary their value according to the temperature. The ohms value can go up or down when the temperature increases.
 +
 +{{ :​component-cheatsheet:​thermistor-on-ice.png?​direct |}}
  
 Switch to the resistance setting. Switch to the resistance setting.
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 You can do the same by walking outside in the warm sun and observe the reverse effect. You can do the same by walking outside in the warm sun and observe the reverse effect.
- 
----- 
- 
-===== Varistors ===== 
- 
-A varistor is a resistor where the value of the resistance varies depending on how much voltage is applied to it. I have no method or resources for testing these yet. 
- 
-These components are very frustrating to identity because they often are almost identical to some dipped ceramic capacitors. And information for differentiating the marking is few and far between. So here is one site at least that helps teach you how to [[http://​epicbeardquest.blogspot.com/​2015/​03/​is-that-varistor-or-capacitor.html | identify the different markings between a varistor and a capacitor]]. 
  
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   - Measure between ''​Common Ground''​ and the ''​Normally Closed''​ pins with voltage across the voltage pins. There should be no connection.   - Measure between ''​Common Ground''​ and the ''​Normally Closed''​ pins with voltage across the voltage pins. There should be no connection.
  
-A great fresher on many types of relays can be found here: [[What is relay | https://​projectiot123.com/​2020/​03/​28/​what-is-relay]]+A great fresher on many types of relays can be found here: [[https://​projectiot123.com/​2020/​03/​28/​what-is-relay | What is relay]]
  
 ---- ----
  
 ===== Transformers ===== ===== Transformers =====
 +
 +<WRAP center round alert 90%>
 +Transformer voltages can be very dangerous. This section assumes there is no power and the transformer is removed from the circuit.
 +</​WRAP>​
 +
 +
 Transformers are a whole can of worms (actually a can of iron and copper), so I won't go into great detail here. I'll just outline the regular steps you can take for sanity testing a transformer. Transformers are a whole can of worms (actually a can of iron and copper), so I won't go into great detail here. I'll just outline the regular steps you can take for sanity testing a transformer.
  
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   - https://​www.youtube.com/​watch?​v=QqWM3pBirzM   - https://​www.youtube.com/​watch?​v=QqWM3pBirzM
   - https://​www.youtube.com/​watch?​v=D0OQvuux6CE   - https://​www.youtube.com/​watch?​v=D0OQvuux6CE
 +
 +----
 +
 +===== Varistors =====
 +
 +Ok, these suckers are tricky to test. They look like a capacitor, or a thermistor, but are nothing like them. Rather than try and explain how to tell them apart, you are better off using this [[http://​epicbeardquest.blogspot.com/​2015/​03/​is-that-varistor-or-capacitor.html | excellent identification guide]].
 +
 +Varistors do not test like a resistor, so the resistance measurement will show no connection or continuity.
 +
 +{{ :​component-cheatsheet:​varistor-testing.png?​direct |}}
 +
 +You can test them like a capacitor using a multimeter or GM-328. Don't expect a value that looks like something on the packaging. Just know if you get a low (pF) range value, you have some confidence that you have a working part. Again, check the guide above to get an appreciation of the expected values.
 +
 +In my example is a TVR 10561. The 10 is component 10mm wide. The 561 is a 560V tolerant unit. If I mistook the 561 as a 561pF part, it will actually test at around 220pF mark which is roughly half, which lines up with the guide above.
 +
 +----
  
 ===== Conclusion ===== ===== Conclusion =====
  
-This article is likely to expand over time. If this is handy for you, please pass it along to friends ​and let me know. I love to hear from other repairers.+This article is likely to expand over time. If this is handy for you, please pass it along to friends. I love to hear from other repairers, if you spot anything wrong, please let me know. 
 + 
 +A massive thanks to Wayne@WaynesWorld,​ Andrew V and Keystone for proofing this article. Really appreciate it. 
 + 
 + 
 +===== Coming Next ===== 
 +PNP transistors :: Gas Discharge Tubes
electronic_component_testing_cheatsheet.1644322360.txt.gz · Last modified: 2022/02/08 12:12 by sausage