Testing an SCR - STA 2080

[micrometer]

I pulled SCR 701 off the protector board for testing. I'm following instructions from Ylli - You can do a basic functional test of the SCR with the diode range of your DMM. The gate to cathode should look like a diode; the anode to gate and the anode to cathode should show open circuit. With the meter connected red lead to anode and black lead to cathode, momentarily connecting the gate to the anode should turn the SCR on. If may or may not stay on after disconnecting the gate lead depending on if the meter supplies enough 'holding current' to the device.

The gate to cathode showed on my DMM as .008 vdc. Should it be more like a .600 vdv as a normal diode voltage drop?

Would my results indicate a bad SCR?

 

[tarior]

Did the SCR turn on as described in the quoted test procedure?

 

[micrometer]

It did give a voltage drop (.450 vdc) and then went to zero.

 

[tarior]

It should read as an open until you touch the anode to the positive lead of your meter, then it should read as a short. Read the procedure again. An analog meter actually works better than a digital for this.

 

[micrometer]

I pulled the SCR and tested it with my DMM set to diode mode.

Gate to Cathode - .009 V
Anode to Cathode - OL
Anode to Gate - OL
+ on Anode/- on Cathode; touch wire from Anode to Gate - .390 V to .009V

What do you think?

 

[tarior]

Sounds like it works.

 

[micrometer]

Sounds like it works.

Thank you, tarior! My first encounter with a SCR.