Smoke Triac Replacement

The 2N6071 works just fine.

Thanks Dale, I figured it would, but I also figured I might as well check in case I was missing something!

I have one with the 2N6071 that I have to replace, and I noticed the earlier ones used the T2322B, which is a lower rated part. Nice to be able to stock one part to fix the old ones as well.

Curious that the triac went out, I tested with another older R2LC and the current was less than an amp to the smoke unit, and all was well in the wiring.

Could there be a "cold wire" surge, like an incandescent bulb? I would think that the ratio of cold to hot would be a lot less than the typical 5x of a light bulb.

I would think a resistor would change a bunch less than a bulb. It's starting at 20 ohms cold as measured, hard to believe that would tax a triac that will handle 4A. I realize that's probably with a heatsink, but any surge would be very brief.

Maybe someone tinkering shorted the smoke unit, this is not a new locomotive.

John, I think you also need to consider the Watt rating of the Triac. I have seen this in the bipolar transistors on the DC reverse units. While they can handle 8 amps and 80 volts, they can't handle both. Some components have a lower rating like 36 watts. At 12 to 18 volts the amperage capability is going to be lower than the rated amps. G

I realize that, however in this case I don't think that's a real issue.  Remember, the ratings of the one that I'm replacing are less in every way.   Hopefully, that's still something I remember from 40 years of electrical engineering practice.

John, I was answering how your original one may have expired despite the current load being less than the rated current load.

 

If you look at the data sheets closely, you will see that both are the same wrt the Gate limits.  Maybe the Gate failed over time.

 

How long you been retired...:-)  G

Like I said, the current was less than an amp, and that triac should be able to handle that easily, even without a heatsink.  I also have a bunch of locomotives with the older R2LC, and none of them have eaten the triac.  I'm guessing that the output was shorted and cooked the part.

Is there any chance the smoke element was shorted to the smoke chamber housing at one time? This or any short in the circuit form the R2LC to the smoke unit would cause havock.

I got the locomotive used with the smoke already non-working, so anything's possible.  I took it apart and repacked the smoke unit, also checked the wiring.  Replaced the part and all is well, or at least as well as a Berkshire Jr. smoke ever is.

Gunrunnerjohn I was replacing the resistor in my k-Line b6 I did not get the one side insolated good and My r2lc triac started to smoke. It looks a little Damaged but it still works. Will it last over time Or is the part going to crap out over time due to The overheating? The element still gets hot but was curious about this before loco reasembly! I wish I knew more about small electronics like You and dale m. !

Well, I'd probably get a replacement and keep it handy, if it shows signs of heat it could croak.  OTOH, it may last forever, there's no way of knowing.  You can just run it until there's a problem, there may never be one.

Thanks will get repacent. Where do you buy just the triac as mentioned in this thread?

The triac I mentioned, 2N6071, will work in your board.  I bought them at Digikey

John checked web sight wich 2071 is it the have several listed?

Sorry I ment 2n6071.

I'd use this one, it's the one I'm using: 2N6071AGOS-ND  The other one has a lower gate current, but this one is lower than the original for older boards, the T2322B.