How to test a Triac

[John (oldandslow)]

Can you test a triac while its still on the board?

How do you test a Triac in or out of the board?

I have two channels that come on the same time 8 and 9

[TheDucks]

I don't suspect a TRIAC. 8 + 9 are on opposite sides of the board. I suspect the channel decoder circuitry.feeding the OPTO's

Just to be clear: These ports turn OFF, Turn ON (full) and are otherwise controllable???  For the test, you are using a small Incandescent load (C7 or larger)?

Usually a bad TRIAC is stuck: On, Half, or OFF (which could also be the OPTO)

[John (oldandslow)]

8 minutes ago, TheDucks said:

I don't suspect a TRIAC. 8 + 9 are on opposite sides of the board. I suspect the channel decoder circuitry.feeding the OPTO's

Just to be clear: These ports turn OFF, Turn ON (full) and are otherwise controllable???  For the test, you are using a small Incandescent load (C7 or larger)?

Usually a bad TRIAC is stuck: On, Half, or OFF (which could also be the OPTO)

Yes, it is controllable. If I put a 40 watt light bulb on both and they still go on and off together then it is NOT a triac if I under stand you right. 

Thank you for replying

John

[TheDucks]

13 minutes ago, John (oldandslow) said:

Yes, it is controllable. If I put a 40 watt light bulb on both and they still go on and off together then it is NOT a triac if I under stand you right. 

Thank you for replying

John

That is my theory. the same command is getting to the wrong destination.  Look at the big flatpack, which seems to be the sole source of commands. (the other chips seem to be power or driver related)

Look for corrosion or smeared solder where the 2 signals run next to each other (then fan out to the OPTOs on opposite sides)

[k6ccc]

100% agree - not a triac problem.

 

[John (oldandslow)]

Thank you all for the feed back. I think I will send it in to be fixed.