I have found continuity between the cathode and gate of this high power thyristor module , is this a sign of bad component ??
or is it something normal for this type of SCRs

 

If it is zero ohms in both direction, then this indicates most likely shorted, there is normally a difference in resistance depending on polarity of the meter, there is direct continuity between the centre screw and the trigger terminal 5 as seen on the diagram.
Are you testing on the resistance scale or diode check?
Max.

 

on some of these modules, there is about 21 ohms between the cathode and gate.

 

If it is zero ohms in both direction, then this indicates most likely shorted, there is normally a difference in resistance depending on polarity of the meter, there is direct continuity between the centre screw and the trigger terminal 5 as seen on the diagram.
Are you testing on the resistance scale or diode check?
Max.

I have just took a test with diode mode , and it displays 000 + beeping .

i didn't check with ohmeter . i will and see what this is giving

 

I get 15 ohms either direction with analog meter.

Here is how I test.
Light bulb with 120vac and a 1K trigger.

 

I have just took a test with diode mode , and it displays 000 + beeping .

i didn't check with ohmeter . i will and see what this is giving

Digital meter reads erratic on ohms and diode test.