DiyLightAnimation
Hardware => Lynx Express => Topic started by: lineman on September 07, 2010,
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Need some help trouble shootin, I don't have any 3 volt or 5 volt leds lit up on LEv5 also the transformer gets extremly hot , here are some pic,s
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That sure sounds like a short - don't leave it plugged in for more than a few seconds at a time to avoid burning things out. The capacitors look like they are in the right way. I can't see enough of the bridge rectifier (the round critter above the big capacitor), but I'd check to make sure it's in correctly. Also verify that the two regulators (with the silver heatsinks) are facing the right way and are the right ones. Do any of the other parts (especially the bridge rectifier and regulators) get hot?
/mike
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The bridge rect. is in correct + on the + check to see if it was gittin hot and it started to get warm along with the trans so I poweed off
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As Mike says, it *looks* like the components are in right (though we can't see the rectifier or the regulators).
Look for shorts in your soldering - bridging two pins.
The glare from the lighting (flash?) makes it very difficult to see enough detail on the solder joints to tell if there's a bridge - though I do see a couple of possible ones. It also looks like there might be a couple of joints that weren't soldered (though that shouldn't cause the problem you're seeing - and it could just be my imagination anyway).
I'd suggest you go back & touch-up any joints that might be questionable.
--Dave
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Did you check the regulators? If the LEDs are in correctly and not lighting, that implies that the problem (short, wrong or reversed component) is somewhere between the transformer and regulators (electrically). There's not much there; just the bridge, big filter cap, and regulators. The regulator pinouts are different, so maybe they are swapped?
/mike
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Did you check the regulators? If the LEDs are in correctly and not lighting, that implies that the problem (short, wrong or reversed component) is somewhere between the transformer and regulators (electrically). There's not much there; just the bridge, big filter cap, and regulators. The regulator pinouts are different, so maybe they are swapped?
/mike
I am pretty sure the 7805 and ld1117 are correct but to verify how can I do this with out desoldering the heat sink so I can read them More PICS
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It is hard to remove the heat sink.
When building by LE's I took a pencil and on the heat sink tab marked them 3.3 & 5, then inserted the appropriate regulator in the heat sink.
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If the LEDs are in correctly and not lighting, that implies that the problem (short, wrong or reversed component) is somewhere between the transformer and regulators (electrically). There's not much there; just the bridge, big filter cap, and regulators.
Mike,
Sorry, but that's not correct. Everything "down-stream" of the regulators is also in the circuit & must be checked. Note that the LEDs connect from the regulator outputs to ground - they don't "feed" the rest of the circuitry (they're effectively in parallel with the rest of the down-stream components). Any shorts "down-stream" of the regulators will draw enough current to "kill" the transformer output (preventing the LEDs from lighting).
Lineman,
Again, check your solder joints first. After touching them up, making sure there aren't any solder bridges, then you might need to check the regulators. The only way I know to do that is to de-solder the heat sinks & remove them. In my opinion, that's a last resort.
--Dave
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I know this has nothing to do with it but; is it really important to solder the heat sink to the board? It appears they would have the same effectiveness even if they were not.
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I know this has nothing to do with it but; is it really important to solder the heat sink to the board? It appears they would have the same effectiveness even if they were not.
Electrically, no - but mechanically, yes. If / when the LE gets bounced around, the mass of the heat sinks could cause the regulators to bend over, possibly breaking a lead or shorting something out. So, it's a good idea to solder them down.
--Dave
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Ok I have resoldered everything still no go did a little testing not long though hope I didn't burn up anything anyhoo First Bridge rec. HOT between legs is 1.5 volts, on the trans also hot from neutral on power cord to pin 1 nothin pin2 120 volts pin 3 nothin pin4 120 volts PINS 5,6,7,8 about 8 volts hope this helps I guess next step desolder 3.3 reg and 5v reg but I will wait for yalls suggestion THANKS FOR THE HELP
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Pictures look good. I think it is likely the regs are swapped. Start with desoldering just one heat sink. You do not need to remove the regulator to get the heatsink off. It will take lots of heat because it is a heat sink so it will get rid of the heat.
RJ
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Pictures look good. I think it is likely the regs are swapped
The regs are where there suppose to be I took a pair needle nose and pulled up on the front lip of the heatsink and verified they were correct then bent the metal tap back down hope this was ok not any good at desoldering anyhoo whats should I do next I did notice the LD1117 on the PCB did not match the reg it say LD33cv I believe in a post RJ said thats because they did not have room for the whole # but it is where the LD1117 goes. Thanks for Helping ME
PS I looked at the legs when I had the tap up no solder bridges there
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Greetings,,,
The 5 volt reg was actually the 5 volt and not a triac?
Keith
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Greetings,,,
The 5 volt reg was actually the 5 volt and not a triac?
Keith
It says L7805abv it was packaged with the LD1117 that is the 5 volt right
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Hi Lineman,
Sounds like your regulators are right. 78c05 is the 5 volt one; and the one marked LD33cv is the 3.3v one (LD1117V33C) - you'll see in the LE manual, step 4 that these are the correct markings.
So from here, I'd suggest doing the following:
1. remove the RS-485 devices (2) and the optocoupler from the sockets. Try powering it now.
2. After removing power, check to see if any of the other components got warm / hot. In particular, check the capacitors.
3. While you're at it, check to see if one of the voltage regulators is getting warm. If so, which one?
Based on what you find from the above, the next step might be to use your ohm meter to see what's shorted.
Hope this helps.
--Dave
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Hi Lineman,
Sounds like your regulators are right. 78c05 is the 5 volt one; and the one marked LD33cv is the 3.3v one (LD1117V33C) - you'll see in the LE manual, step 4 that these are the correct markings.
So from here, I'd suggest doing the following:
1. remove the RS-485 devices (2) and the optocoupler from the sockets. Try powering it now.
2. After removing power, check to see if any of the other components got warm / hot. In particular, check the capacitors.
3. While you're at it, check to see if one of the voltage regulators is getting warm. If so, which one?
Based on what you find from the above, the next step might be to use your ohm meter to see what's shorted.
Hope this helps.
--Dave
Removed the 2 485 chips and the H11aa chip this is tho opto right and the only thing that get hot is the round black bridge rectifier top left above 2700 uf and the trans. reg cool and the 2 100 uf cool to the touch
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If it is not a solder bridge I am leaning to a bad diode in the bridge. Would be a first time I have seen this but not impossible I guess. You will need to desolder it and take it off. Then put your ohm meter on the pcb pad for + and the diagonal one for the ground. See if you have a short. If not then a new bridge would be called for. If you find a short there it is time to start looking for a solder bridge again.
I would look again for a solder bridge. 99% of the time it is not a bad part. Most of the parts used on this design is pretty tough.
RJ
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Just a side comment.
Many years ago working as the lead technician in a electronic production department. I ran across a unit that would not work correctly and no amount of testing would find the problem.
Determined as I was in my youth, it took me a couple of hours to find the problem and not by using a meter or oscilloscope.
It took a good magnifying glass and a very close inspection of the PCB. What I found was in the process of making the PCB circuit board, there must have been a scratch in the PCB or photo process and it left a VERY tiny bridge between 2 circuits.
Looking at it with just your eye you could not see it, only the magnifying glass and a good light would show it.
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Would be a first time I have seen this but not impossible I guess. You will need to desolder it and take it off. Then put your ohm meter on the pcb pad for + and the diagonal one for the ground. See if you have a short. OK I HAVE DESOLDERED THE RECT. OR SHOULD I SAY DESTROYED IT BUT NO HARM TO PCB, TOOK A OHM READING FROM THE + AND THE DIAGONAL AND GET A READING OF 20.00 THIS NORMAL I ASSUME BECAUSE A SHORT WOULD ZERO OUT RIGHT IF ALL IS GOOD THEN SHOULD I ORDER ANOTHER RECT. AND TRY IT OR IS THERE ANY OTHER TESTING I NEED TO DO BEFORE SOLDERING IN NEW RECT. IT IS A PAIN TO GET OUT I HAVE A SPARE IT CAME WITH THE OTHER LE KIT
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If you are saying 20 ohms then it seems way to low. This would calculate out to over .6 amps which the whole board does not draw that much current.
RJ
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If you are saying 20 ohms then it seems way to low. This would calculate out to over .6 amps which the whole board does not draw that much current.
RJ
Yes the ohms stop at actually 20.56 I will try another meter to verify also can I just put the Rect in and not solder just for a short test like plug in and unplug
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If it is not a solder bridge I am leaning to a bad diode in the bridge. Would be a first time I have seen this but not impossible
RJ now you have seen one I put the new bridge RECT in and get 3 volt and 5 volt LEDs thanks for everyones help well its to mouser to order a RECT for the other LE .
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I put the new bridge RECT in and get 3 volt and 5 volt LEDs
Wow. Wild. I never would have imagined...
Sure glad you got it figured out!
--Dave
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I am just glad you found the problem and got it working.
RJ