cmoore60 Posted December 4, 2009 Share Posted December 4, 2009 Simple suggestion here. I have been following this thread and this just came to mind.The right side of the board controls the 8 channels 9-16 and also the on board electronics. I believe that the first thing electrically on the right side is the transformer. The remainder of the electronics are behind the transformer.What happens if you remove the 2 jumpers for setting the input voltage on the transformer and power the board?My thought process is. If it does not trip the breaker with the jumpers off, then very likely a bad transformer. IF it still trips the breaker, then look towards a shorted to ground triac.Chuck Link to comment Share on other sites More sharing options...
Rafter Bar R Posted December 4, 2009 Share Posted December 4, 2009 I thought that too, but with a 20 amp breaker going, that would "smoke" the traces that go to the transformer off the board. Usually when a transformer goes bad, it goes open, the windings are too fine to handle that kind of current. Link to comment Share on other sites More sharing options...
94-302-vert Posted December 4, 2009 Author Share Posted December 4, 2009 So then we are thinking a triac? How do I test them? Link to comment Share on other sites More sharing options...
cmoore60 Posted December 4, 2009 Share Posted December 4, 2009 I would not rule out anything, unless you can prove otherwise.Chuck Link to comment Share on other sites More sharing options...
Rafter Bar R Posted December 4, 2009 Share Posted December 4, 2009 This is a question that would be best answered by Dan. LOR uses isolated triacs on their boards. What is the likelyhood that the internal "isolation" between the triac's electronics and the metal heatsinking tab has broken down on one or more triacs. This would allow for short into the heatsinks if they are grounded.Sidenote: Triacs and SCR's come in both isolated and nonisolated versions. The nonisolated versions allow for current to be recieved or dumped into the heatsinks which are enegized. The isolated version which LOR uses are safer for this application because no current makes it into the heatsinks. The heatsinks are isolated from any voltages.The only way to find this problem is to remove the heatsinks then power up the board. If the breaker doesn't trip, then I would use a voltmeter rated 120 VAC or above and check each triac. Red lead to the triac and the black to neutral and test each one. Link to comment Share on other sites More sharing options...
Max-Paul Posted December 5, 2009 Share Posted December 5, 2009 Lonewolf,This is why I asked if he had replaced any of the Triacs earlier. I thought that he had said that this board had been working before. But I suppose that this would be one of the failure modes of a Triac.So, removing the board from the heat sind and testing like lonewolf said between the heat sink tab on the Triac and the hot input tab with fuses in place is a possible fault / failure test. Link to comment Share on other sites More sharing options...
94-302-vert Posted December 7, 2009 Author Share Posted December 7, 2009 You know what... I put the entire board back together EXCEPT bolting the tiracs to the heatsinks... for kicks I plugged it in while holding it yesterday (leather gloves) and it powered up OK (right side only no jumpers).HMMM.... maybe now I need to try this with atttaching one triac at a time????Thoughts? Link to comment Share on other sites More sharing options...
-klb- Posted December 7, 2009 Share Posted December 7, 2009 Have you taken an ohm meter from each triac tab to the hot inlet? Might be a place to start... Link to comment Share on other sites More sharing options...
94-302-vert Posted December 7, 2009 Author Share Posted December 7, 2009 -klb- wrote: Have you taken an ohm meter from each triac tab to the hot inlet? Might be a place to start...I don't do circuitry. Which of the 3 leads would I ohm for that?How do I check a triac? Link to comment Share on other sites More sharing options...
-klb- Posted December 7, 2009 Share Posted December 7, 2009 Check resistance between the part that bolts to the heat sink and the narrow lead of the power cord.If you don't read any as other than open circuit, the next step is to power it up again, and measure voltage between neutral (wide blade) and the heat sink mounting tab. They should all have no reading. If you get 115 volts on one of them, you have found your problem.. Link to comment Share on other sites More sharing options...
94-302-vert Posted December 7, 2009 Author Share Posted December 7, 2009 Great explanation. Thank you. Link to comment Share on other sites More sharing options...
Max-Paul Posted December 8, 2009 Share Posted December 8, 2009 The suspense is killing me, Vert. Is one of your Triacs hot on the tab?Max Link to comment Share on other sites More sharing options...
94-302-vert Posted December 8, 2009 Author Share Posted December 8, 2009 Well I didn't plug it in last night as I didn't want to plug it in with the show running (suddenly have a portion of the show go out)... BUT I did OHM from the mouting tabs to hot and all were OC.GRRRR....I just don't get it. The board didn't work for a week, then a week later it plugs in fine... I don't want to trust this board.... Tonight I'll have time after the kids are in bed to fiddle with it... Link to comment Share on other sites More sharing options...
eldoradoboy Posted December 8, 2009 Share Posted December 8, 2009 if this is a new board it seems you have already lost a lot of show time with it... maybe just RMA it to LOR and get a new one?with you being on the east coast I cant imagine shiping it to LOR to take very long?-Christopher Link to comment Share on other sites More sharing options...
94-302-vert Posted December 8, 2009 Author Share Posted December 8, 2009 eldoradoboy wrote: if this is a new board it seems you have already lost a lot of show time with it... maybe just RMA it to LOR and get a new one?with you being on the east coast I cant imagine shiping it to LOR to take very long?-ChristopherThe board is just over a year old. I bought the kit in the sale last summer (2008).At this point I am just goign to run the show without it... Link to comment Share on other sites More sharing options...
Max-Paul Posted December 8, 2009 Share Posted December 8, 2009 Ok, well you are making progress. Well so it seems to me. You just eliminated an internal short within the Triacs to the heat sink tab of the triac. So lets see if I remember what has happened. With the heat sink attached to the board, but with the triacs not attached to the heat sink, no short. Yet the latest test does not indicate that there is any short within the Triac. So, what is going on? Do you have the heat sink mounted to the board only at this time? If so, is the heat sink O.C. to the hot lead/terminal? If so, start putting the Triacs back on the heat sink. Stop and do an ohm test again between the H.S. and Hot lead. If it is still O.C. then add the next Triac. Continue till you have a short.Its got to be the heat sink or triacs that are causing the short.Also check all of the leads to the triacs. Make sure that the leads below the board are clipped back and do not extend past the board's edge. Make sure that the leads above the board are not bent in such a manner that they would extend past the edge of the board.Just a thought, I took all four of my boards once they were completed. And cleaned them real well with Alchoal then took some clear paint and sprayed them. But first I masked off the quick disconnect terminals, fuses, chips in a socket, and the body of the triacs. Back side so that it could conduct heat to the heat sink. Then I sprayed both top and bottom. This is to help reduce the chance of shorts. I know, not much help right now. But think about it this summer. Link to comment Share on other sites More sharing options...
-klb- Posted December 8, 2009 Share Posted December 8, 2009 I think there is still some validity in checking the triac mounting tabs with power applied. After all, there may be a flaw where the gate is shorted to the power applied side of the junction, and the other side is shorted to the tab. So an unpowered test would likely miss the short, as there would be no power to trigger the gate. Likely a rare case, but after all, we seem to be deep in the realm of rare failures here. Link to comment Share on other sites More sharing options...
Max-Paul Posted December 9, 2009 Share Posted December 9, 2009 Also along those same lines klb. The failure might have a small gap, were 9vdc is not enough to jump that gap, but 120vac will jump the gap and complete the circuit. So, yes, I agree a powered test looking for a voltage to be where it is not suppose to be would be a test I would have done instead of the ohm test. But then too, I work with live circuits daily.klb, I assume you are familiar with the technical term "FM" and I aint talking about radios. Well that is what we are having a case of, FM! Link to comment Share on other sites More sharing options...
94-302-vert Posted December 10, 2009 Author Share Posted December 10, 2009 One triac read 60 vac at the mounting tab. I am going to not attach it and try the board out. Hopefully this weekend..Thanks for the help guys. Link to comment Share on other sites More sharing options...
Max-Paul Posted December 10, 2009 Share Posted December 10, 2009 Thanks Vert for the feedback. Yes we would still like to hear what happens when you reinstall the heat sink, but do not mount the one Triac.Well klb sounds like you get the point on this one. Good call.. Link to comment Share on other sites More sharing options...
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