DiyLightAnimation
Hardware => Lynx Express => Topic started by: urthegman on April 17, 2012,
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Hello all, After putting one of my Expresses in its case and attaching a power cord, channel four would light up during the sequential channel test but then flicker when all of the channels flashed. Upon visual inspection, one of the socket pins was not showing through the solder on the bottom. I tried an easy solution of inserting a pin through that spot to see if I could construct some sort of contact point to that leg of the opto. This did not work. I also swapped the chip out with a working one and that didn't work either. So I removed the socket and discovered my suspicion to be true, one of the pins was bent under the socket. Here is my dilemma, when re-inserting the socket I noticed the metallic top ring of one of the pass throughs was missing. (my camera is not working otherwise I would have included a picture) Is there anything I can do to ensure contact with the trace when I put the socket back in? Thanks for any help you can give, George
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maybe from this link http://www.diylightanimation.com/wiki/images/a/a0/LEv5-1.jpg photo tell tell us what IC # and pin # then maybe someone tell you :D
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If the missing pad is on pins 3 or 5, don't worry; those pins are not used. If it is pin 2, be careful inserting the socket so that the solder-side pad is not damaged, and solder it on the bottom. If the bottom side trace on pin 2 is damaged, solder a jumper wire between pin 2 and the green LED next to the opto, replacing the trace.
If the damage is to pads 1, 4, or 6 on the top, the easiest way to deal with that is to carefully scrape off the solder mask on the trace where it connected to the pad, bend the socket's pin so it sticks straight out the side of the socket, and solder it to the scraped-off section of trace.
/mike
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Sorry, It is the one for channel four and of course it is the one on top of the board right next to the trace that leads to the triac. In the picture it is the on the bottom of the fourth opto all the way to the right.
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If the missing pad is on pins 3 or 5, don't worry; those pins are not used. If it is pin 2, be careful inserting the socket so that the solder-side pad is not damaged, and solder it on the bottom. If the bottom side trace on pin 2 is damaged, solder a jumper wire between pin 2 and the green LED next to the opto, replacing the trace.
If the damage is to pads 1, 4, or 6 on the top, the easiest way to deal with that is to carefully scrape off the solder mask on the trace where it connected to the pad, bend the socket's pin so it sticks straight out the side of the socket, and solder it to the scraped-off section of trace.
/mike
I'm not sure how the pin counts go, based on the picture is this schematic correct? 5 3 1
6 4 2
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3 2 1
4 5 6
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Thank you everyone, glad I was patient with this,that is what I love about this place, since it is pin 6, I NEVER would have thought of carefully scraping off the solder mask and soldering the pin to the trace on my own!!! I thought I would be running to Radio Shack for some kind of tape that might bridge the connection somehow, this solution saves me a trip and is much easier! I'll let you know how it works out.
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Ok, I got the socket back in and after scraping enough of the solder mask off to create contact I was able to solder pin 6 on the socket to the trace leading to the triac. I put the opto chip in the right way plugged the Express in and after initially lighting up channel 4 once again started flickering sporadically. >:( I touched up the solder points for the opto and triacs as well as the one for channel 4 on the pic and tried it again with the same result (flickering sporadically). I attached a power cord with some lights coming out of channel 4, plugged it in again and the lights flickered but not as frequently as the channel 4 led on the board. I swapped the opto chip but still had the sporadic flickering. Question, if the led was in backwards on the board, would it flicker? Also could it be a bad triac? Should I try the controller with a pic from another controller?
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If the led was in backwards, it would stay off.
If you have another pic, I'd try swapping it just because that is easy...
Triacs can do funny and strange things. However, if the led is flickering, the triac is probably ok.
The trace runs like this. +3.3v -> opto -> led -> pic.
It looks like channel 4 goes to pin 6 on the pic, so you should check there and make sure that solder joint is ok and that the pin is not bent under on the pic.
The opto provides isolation between the low voltage and high voltage parts of the circuit. If the led is flickering, the probability of something from the high voltage side leaking back through the opto and causing it is really low.
RM
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Sounds like a high resistance connection on the low voltage side. (Pic, Led, Opto) any added resistance to lead to problems here where it is hard for the opto tp trigger reliably so you can get flickering.
RJ
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I tried a different pic and the solder joint on pin 6 looked good but I retouched it anyway and changed the led also with no luck. I am going to order a new socket and replace the one I have in there now and hopefully that will work.
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You can get a 8 pin socket from Radio Shack, Just snip off the 2 extra pins.
http://www.radioshack.com/product/index.jsp?productId=2062604&filterName=Type&filterValue=IC+sockets (http://www.radioshack.com/product/index.jsp?productId=2062604&filterName=Type&filterValue=IC+sockets)
Good luck
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You can get a 8 pin socket from Radio Shack, Just snip off the 2 extra pins.
http://www.radioshack.com/product/index.jsp?productId=2062604&filterName=Type&filterValue=IC+sockets (http://www.radioshack.com/product/index.jsp?productId=2062604&filterName=Type&filterValue=IC+sockets)
Good luck
Never would have thought of that! And I have a spare eight pin socket! Thanks!
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Can you post some pics of your board?
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I will be getting a new camera tonight and should be able to post one then.
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Here are the pictures, I will try and take better ones in the daytime? <fp.
First one is where I soldered pin 6 to the front of the board.
The second one is the back of the board.
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does anybody know how much current passes along that trace? could you solder a wire from the pin in the socket to the appropiate lead on the triac? or whever that traces runs?
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That pin is at 110V potential. Be carefull!
This part of the chip operates the triac "output side", and will not affect the led side of the chip.
Take a good look at pins 123 the led and the pic chip again, something else is going on. Retouch the solder joints, look for another broken trace. If you have a multimeter, use it to trace out the led side of the opto back to the microchip.
Good luck
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I can't really tell from the picture, but you solder joints look a little dull - that's an indication that your iron may not be hot enough.
I like to work with a really hot iron and just don't keep it in one place very long... The solder, lead, and pads on the board need to get hot enough so that the solder flows through the board. While all of the holes are supposed to be copper plated going through the board, sometimes you get one that has a poor connection. If the solder flows through, it will also make the solder joint connection to the trace on the other side.
Your problem is on the low voltage side. Once that is working, we can determine if there is a problem on the high voltage side.
Pic, led, opto, solder joints and traces between those components.
I'm leaning toward pic pin 6 or the led not having a good connection to the trace on the top side of he board.
Good luck!
RM
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I suspect that while removing the opto sockit, one of the traces going to pin 1 or pin 2 got broke. I would remove the sockit again and replace it.
1. Remove sockit.
2. Clean off all solder with a sucker, or desoldering wick.
3. Then using some fine sandpaper, remove the solder mask to expose clean shinny copper traces, All 4 top and bottom".
4. Then before inserting the new socket, bend out pins 1, 4, 6.
5. Insert socket and bend out pins 2, 3.
6. Now solder pins 2, 3, 5 on bottom of board, ensuring good solder flow.
7. Flip the board and solder pins 1, 4, 6 on top of board, ensuring good solder flow.
My cheepo camera will not give me a helpfull picture. But, I think you get the idea.
1. Channel 4 starts out at the 3.3v supply, hooked up to pin 1 of all the optos.
2. From pin 2 of the opto to the + side of the green led.
3. From the - side of the green led to pin 5 of the pic chip, and pin 5 of the ICSP.
If this all checks out good I would consider the led suspect, Not often, but it does happen.
Hope this helps
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Thanks, I couldn't ask for directions that are more clear than that!!! I already swapped out the led so we know it's not that. I will be working on this this afternoon. Question, if a solder joint is dull instead of shiny, I know it means the soldering iron is not hot enough, but does it mean that the joint will not conduct electricity/work or if there is trouble with that item that the dull joint could possibly be the problem?
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A dull solder joint usually means it has not been heated enough to flow solder. Overheating the solder joint, or reheating the solder joint can also cause a dull look. Both results will be a weak joint that can fail, or become intermittent. Usually applying a little flux to it, and reflowing it can save it.
Lead free solder also causes a dull look.
Good luck
I did have a bigger writeup but lost it to that blame mouse back button.