180soundtech
- Aug 30, 2013
- 3
- Joined
- Aug 30, 2013
- Messages
- 3
first off, i'm a not a complete idiot when it comes to this stuff, but i'm pretty close; there are some pretty astonishing holes in my knowledge on electronics, so sorry in advance. not sure if i've got everything right, so stop me when i don't make sense.
so, i'm trying to repair a bunch of led stage lights for my church. there are about 90 5mm through-hole leds in a light, all on one board (something like 40 red, 25 green and 25 blue). four wires come from the control board to the led board; +12 volts, red green and blue. mosfets on the control board connect each of the three colors to ground with, i guess pulse width modulation to dim each color.
the red circuit is a number of 4-led-strings-in-series in parallel. each series string has a 201 ohm resistor between the last led and the mosfet, which connects to ground. in a few lights, ive got a string of 4 red leds that are out, and i've probed around, testing each led individually with 5 volts and a 330 ohm resister. i can get three of them to illuminate, but not the fourth. i can even quickly short the led's two pins and get the other three to turn on which i guess means that one has gone bad.
so my questions are this: can i simply short over the one bad led and get the other three to work long term? i imagine that the lowered resistance on that string would cause something to go bad eventually, so do i need to replace the bad led? also, leds don't really burn out ... so any ideas why the led is bad? will another led go bad again because of some bigger problem?
p.s. i'm asking because i'm having this problem in several of my lights, not just one
so, i'm trying to repair a bunch of led stage lights for my church. there are about 90 5mm through-hole leds in a light, all on one board (something like 40 red, 25 green and 25 blue). four wires come from the control board to the led board; +12 volts, red green and blue. mosfets on the control board connect each of the three colors to ground with, i guess pulse width modulation to dim each color.
the red circuit is a number of 4-led-strings-in-series in parallel. each series string has a 201 ohm resistor between the last led and the mosfet, which connects to ground. in a few lights, ive got a string of 4 red leds that are out, and i've probed around, testing each led individually with 5 volts and a 330 ohm resister. i can get three of them to illuminate, but not the fourth. i can even quickly short the led's two pins and get the other three to turn on which i guess means that one has gone bad.
so my questions are this: can i simply short over the one bad led and get the other three to work long term? i imagine that the lowered resistance on that string would cause something to go bad eventually, so do i need to replace the bad led? also, leds don't really burn out ... so any ideas why the led is bad? will another led go bad again because of some bigger problem?
p.s. i'm asking because i'm having this problem in several of my lights, not just one