How to test an SCR in TO-92 package

[Electronics123]

I'm trying to test an SCR (it's labeled pcr406). I've tried testing several using the instructions in this video. Everything works the same way, indicating a good SCR, until the last step. I don't get continuity when I touch the red probe to the cathode and the black to the anode. Then I get a short when I move the black probe so it touches both the anode and the gate at the same time. But when I release the gate, keeping the probes on the cathode and anode, the resistance goes up immediately. Am I doing something wrong? Is this a different component than I thought it was?

 

[KlausST]

Hi,

first thing: not every SCR works identically... if they did: why do we have so much different ones?
next thing: not every multimeter works the same ..

Conclusion:
* Read the datasheet about operating conditions of your SCR.
* build a circuit that geneartes these conditions and see if the SCR operates like expected.

Klaus

 

[Electronics123]

first thing: not every SCR works identically... if they did: why do we have so much different ones?
next thing: not every multimeter works the same ..

Conclusion:
* Read the datasheet about operating conditions of your SCR.
* build a circuit that geneartes these conditions and see if the SCR operates like expected.

I don't have a datasheet for it. Just ones for various manufacturers on the web. I'm repairing a device (paper shredder) and bought a bag of replacements from Amazon. Can you recommend a circuit? I'm new at this.

 

[betwixt]

It's made by "Jiangsu ChangJiang Electronics Technology Co. Ltd" and has 400V 0.6A rating. The critical factor in your test is it has a holding current of 5mA, your test meter almost certainly passes less than that through its probes so the SCR goes back to non-conducting mode.

Brian.

 

[KlausST]

Hi

I don't have a datasheet for it. Just ones for various manufacturers on the web.

for proper testing you need to have the specifications. An internet search is essential.
Usually every manufacturer gives information about recommended operation .... and gives test conditions. This is whyt youu need to rely on.

There is no general test circuit for SCRs.
* if they tell to apply 10mA to the gate, then it does not matter where the 10mA come from. 5V vs 50V, limited by a constant current source or by a resistor. 10mA are 10mA.

***

Just in case you find no datasheet ... but you have to use them for repair .. then use the values/circuit of the device to be repaired.

Just applying random values ... and expecting a function ... gives no reliable information.

****

Klaus