BTA416 600C triacs

[shockpoint]

Hi all,

general question here.

Are triacs normally-open devices between MT1 and MT2?

In addition, what's the relationship between MT1 and the gate terminal?

Context - repairing a dyson AM04 heater fan.

The triac in question is BTA 416 - 600C. The resistance between MT1 and Gate is 120Ohms and for a semiconductor this is suspiciously low. BUT, I have limited experience in triacs so this might really be normal behaviour. In support of this suggestion, there is another triac in a separate circuit (not parallel) with this triac, and MT1 and gate reads a similar resistance.

This post here: https://www.eevblog.com/forum/projects/triac-question/ suggests that the 600B variant measures 102ohms across said terminals.

If it's normal behaviour, could someone explain why? In a Mosfet this would suggest a short but why is it part of normal function in a triac?

[amyk]

Are triacs normally-open devices between MT1 and MT2?

Yes.

In addition, what's the relationship between MT1 and the gate terminal?
[...]
The triac in question is BTA 416 - 600C. The resistance between MT1 and Gate is 120Ohms and for a semiconductor this is suspiciously low. BUT, I have limited experience in triacs so this might really be normal behaviour. In support of this suggestion, there is another triac in a separate circuit (not parallel) with this triac, and MT1 and gate reads a similar resistance.
[...]
If it's normal behaviour, could someone explain why? In a Mosfet this would suggest a short but why is it part of normal function in a triac?

https://upload.wikimedia.org/wikipedia/commons/thumb/6/68/Triac_structure.svg/576px-Triac_structure.svg.png

Also worth giving https://en.wikipedia.org/wiki/TRIAC a careful read.

[MathWizard]

Here's an easy to make tester for TRIAC's and SCR's, IDK where I foud this schematic, but it works with AC,  or a DC supply to get the DUT conducting in 1 direction or another. Lately I tested a 600 or 800V heater TRIAC with some 16V in, and it passed some 100mA one way, and 82mA the other. IDK the minimum supply voltage for TRIAC's, but a 9V battery would work too.

It read as 30 ohms, between M1/2. IDK, it's possible I overheated it removing it too, it was hard.