I built a 12 LED array for a small tank. It consists of 6 Blue and 6 whit LEDS driven by two separate Luxdrive buckpucks - the externally dimmable variety.
During the last week, the white string has started to flicker if not driven at the maximum. I thought it might be the pot, so I replaced that. It did not help. I draw the conclusion that it must be the driver (I cannot find any bad connections). Thoughts?
If the driver is bad, this will be the second defective driver for this build - as I had another that did not drive the LED's to proper brightness. I am beginning to worry about using the Luxdrive buckpucks. After all, if you have to replace $15 drivers on a regular basis - it is not terribly cost effective.
can you measure some points with your multimeter? Id like to know numbers across a few things..
first, check for shorts between any LEDs and the heat sink.
Im thinking Id like to know the voltage that is coming in to the buckpuck, voltage and current out of the buckpuck, voltage before and after the pot for dimming control.
I can get voltages. The LED's are mounted with the Bergquist pads that Evil caused to exist, I don't know that a short at the heatsink is likely, but I will look. The light is at the office, so it will have to wait until I can get there.
It always seems to run OK when the pot is set for max current to the circuit. I only have trouble when I try to dim - and it just started, it worked OK for 2-3 weeks.
They are 700mA buckpucks; externally dimmable. I got the multimeter to the office but time did not allow for testing. The buckpucks are not yet enclosed nor is the heat sink. I used an IR thermometer on the heatsink and got readings around 72-74 with an occasional 77 degree hotspot.
I move the power to a regular outlet from a timed outlet and forgot to move it back - the lights were on for about a day and a half before I discovered the mistake. I did not notice them flickering yesterday. I don't know how that could have affected them. It is only one "string" that is problematic. I don't understand why it started after a couple of weeks.
That is strange. The 1000mA Buckpucks have had the highest failure rate, and it's typically been related to heat, which is why I asked. To rule out the LEDs as the issue (most likely not the problem), swap the LEDs and drivers, and see if the LEDs that were flickering work normally on the other driver. If all is good, the driver is toast.
About a week ago, it was so bad that I totally dimmed the white LED's for the remainder of the day and until I returned in the morning. There has been no flicker that I can think of since - even when I adjust the whites to mid level brightness (which is when this will happen). You would think that if it was heat it would not happen first thing in the morning after the unit has been off overnight.
I cannot find a bad solder joint. I could re-solder all of the connections.
I got some measurements, but they don't look to be interesting.
20 V across the series string; 4v varying to 0v at the pot connection; my notes don't seem to make sense on the other reading, I guess I better re-test... the PS is a dual output 24V ps.
If it's only doing it at certain points in the dimming range, then it sounds more and more like a driver issue. Possibly a bad capacitor or inductor that fails at a certain frequency.
Driver problem?
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