Help Please: How to determine and test for TRIAC failure?

[smwilliamson]

So I have two stoves. One is shredding through auger motors (2 per year) and another which is shredding through convection blowers...a loud squeal is evident within days of installing a new motor. Both machines were not surge protected and problems have been ongoing.

I suspect bad control boards. Though when tested for timing, voltage and actuation, all seems fine. How do I test to see if a TRIAC is sending a signal which is no longer a pure sine wave. Is this what I'm looking for?

 

[pastera]

You need an oscilloscope to see the switched waveform to diagnose.

A little info on TRIAC and SSRelays:
http://www.epanorama.net/circuits/semiconductor_relays.html

PM me is you need to borrow an Oscope or just want to replace the triacs on the control boards

Aaron

 

[nailed_nailer]

Scott,

An O-scope will help you out here.

There are over 4000 listed on EBay this morning. From <$50 to >$4000.
You probably don't need anything with much more than 20Mhz bandwidth for stoves.

There are some nice hand helds out there as well. But the smaller they are the more they cost.

If buying a scope, I'd lean heavy toward Tektronics brand. All other manufacturers are playing catch up to them.
Not saying another brand is not good.....just that Tek is the industry standard.

You will also need a probe kit. 10:1 should be fine. Pomona makes good ones.

---Nailer---

 

[Snowy Rivers]

If the triac has gone south, usually the motors will run either way slow/not at all or run full speed.

Another way to tell if the triac is bad is that the motors will whine or make a harmonic noise.

The noise really does not hurt anything, but is anoying.

The triac on my Whitfield Advantage has gone south and I can't control the room air fan speed.

Got it to about 3/4 to full speed and its there to stay until I change the controls this spring.


These stove controllers are so cheaply made in many cases that I certainly would not count on a Perfect Sine wave form.

Even the ceiling fan controllers that you buy for large fans are not the best triacs. They do work fairly well and will usually last a long time.

The tiny little devices placed on these control boards are just that, Tiny.

best of luck sorting out the issue.

Snowy

 

[exoilburner]

If you are going to use an O'scope remember that the negative side of the O'scope probe wires may be connected to 120vac common. So be careful where you connect the probe negative wire; or don't use it; or be sure it is isolated.

 

[UncleAnthony]

Scott,

An O-scope will help you out here.

There are over 4000 listed on EBay this morning. From <$50 to >$4000.
You probably don't need anything with much more than 20Mhz bandwidth for stoves.

There are some nice hand helds out there as well. But the smaller they are the more they cost.

If buying a scope, I'd lean heavy toward Tektronics brand. All other manufacturers are playing catch up to them.
Not saying another brand is not good.....just that Tek is the industry standard.

You will also need a probe kit. 10:1 should be fine. Pomona makes good ones.

---Nailer---

I agree, Tektronix is the industry standard. If you are going to use it long-term, get a good used one, they
last almost forever. One of my favorite is the 465 or 2465 scope with 10:1 probes, can easily setup to see sine
waves . Make sure you get a users manual also.
I used to calibrate and repair o'scopes (hp,tek,others) , and tek is the best (imo).
Good luck !