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Can it be a triac?


Archer

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Thanks Drew....but I guarantee you that I had less heat by doing all 3 at once than by doing them 1 at a time.....I've done it both ways.

Skip the wick in this case until it is out and all you want to do is clean up the board. I'll remove the one I put in and put a different one in its place....I have nothing to lose.

 

Keep I mind that I have installed 640 of these opto components in 40 controllers over the last 4 yrs. This controller worked fine for at least 3 seasons.

Edited by Archer
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I'd start metering from the triac back by staring and comparing to a channel next to the non-working one. I've had bad solder joints in the past so good light and a magnifying glass could be helpful.

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There are a couple of resistors to check.  I believe there is one between the opto and the triac.. There should also be one on the front side of the opto from whatever logic device is driving it.  The output is a pretty simple configuration.  Logic driving the opto's LED via a current limiting resistor and the output side of the opto driving the triac, usually via a resistor.  That is about it.  There could also be a PCB land that has a fracture that you can't see.  An ohm meter will tell you what you need to know.. I assume by your posts that will not be an issue for you to check. 

 

Craig

 

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I always second guess myself that continuity will come from another direction. Or are you saying I should read the value of the resistor if it is good?

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The PCB lands should have almost zero resistance from one point to another with no components in line... However, lets say there is a 100 ohm resistor between the #3 pin of the opto to the gate of the triac.  If I put one lead on the gate and one on the opto pin I should read that 100 ohms, unless of course there are other branches with components that have measurable resistance.. but in your case, you are looking for opens and not shorts (most likely). 

 

One good thing is that you have  examples on that same board to compare to.   Take the next channel over and measure from the output side of the opto to the triac.  Try all combos and compare to the bad channel.  They should all be close.

If that doesn't yield you the results you need, go to the input side of the opto and follow the land back to the IC that drives it.  Again, compare to an adjacent channel and its respective pin on that logic device. 

This hopefully will find your problem.  If it does not, you could have either a bad IC that drives the opto or you could have put in a triac that is bad.... One more thing now that I think about it.. you should also check the 120vac path as well.  All the way from output dongle to input AC cord.  You could have a neutral wire off or a bad crimp on the L1 side.. could be all kinds of things.. Compare to an adjacent channel.

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go here to get an idea of some simple opto triac drive circuits.  They should give you some idea what you are looking for.  https://www.google.com/search?q=opto+triac+circuit&tbm=isch&tbo=u&source=univ&sa=X&ved=0ahUKEwiFmO_Z7bfQAhVL1GMKHaC-CDgQsAQIMQ&biw=1920&bih=922

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It's still a dark channel. Later this evening I plan on removing the "opto" again and install yet another one.....this will be the third. I may replace the triac again too. I will also go over the board with my magnifying glass. After this, I will assign it a position in the lineup that does not require a full complement of channels on the controller if it remains dark.

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I'll give it a try .....when the sun goes down. Too busy getting things in order for the display during the day .

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I went over the board top and bottom with a magnifying glass, replaced the opto again and its still dark. The resister looks like the day I put it in. 

I also measured across the resister and it read exactly the same as the one above and below.

Edited by Archer
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Try this..carefully short out the two output pins of the opto.  That will simulate the opto turning on.. that should turn on the AC lights for that channel. If the lights on the channel comes on, it is not in the AC portion.   If not...

The next thing you can do is carefully.. short out MT1 and MT2 on the triac. STAY AWAY FROM THE GATE..  If it doesn't come on... there is your answer.. check the 120vac connectors and so on.. maybe even a bad dongle wire..

If you do those two tests and the output works, then it pretty much has to be on the logic side..

 

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Check your pins that the HOT and NEUTRAL wires for that channel are attached to, look at the back side of the PCB if you have toi.  I had two channels go dark like that, but before I started messing with replacing parts, and this was found by accident, I was moving the hot and neutral wires out of the way when I noticed 2 of the neutrals soldered was also moving just a hair. 

Under closer examination, those solder joints had broken loose and the contact was still seated, but wasn't making contact to the trace on the PCB, reflowed the solder on those neutrals and a few hots that looked like they needed to be reflowed and all the channels started working again that were out.   

Had a similar problem with a controller whjere all the channels on one side of the board {1-8} all went out, that was the neutral and the hot off one of the power cords from the controller.  Drove me crazy finding that problem, fuse checked out good, but replaced anyway, reset controller several times, checked components, and all the time was the hot and neutral pins had become dislodged enough that no power was going to those channels.

So check your white{Neutral} and black{Hot} wire terminals and connections, could possibly be there causing issues.

Good Luck!

 

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