Hello all, hoping as usual you all can provide some wise technical advice.
I have a SAD* light which uses three fluorescent bulbs. The bulbs are oddballs, 2G10 type. The light seemed dimmer than usual (it used to be quite bright) and when I opened it up, one of the three bulbs was burnt out. Rather than replace it with another fluorescent, I figured I'd switch over to LED. The 2G10 bulbs are rare, and I couldn't get one locally, but did find them online.
(* The SAD light is used to treat Seasonal Affective Disorder, which is essentially poor mood due to lack of sunlight, unfortunately quite common here during our long dark northern winter.)
Received them today, installed them, and fired up the lamp with the cover off (seven screws to remove the translucent cover, so wanted to make sure I had the bulbs seated correctly). The three new bulbs looked great. So I put the cover back on, and none of the three bulbs would light. Wha ...???
Took the cover off again and tried substituting in the two good fluorescent bulbs. They worked fine, but I could not get more than a flicker out of and of the LED bulbs. There was a mild but definite smell of hot electronics. I wondered if I'd smoked something in either the lamp or the new LED bulbs. Took the plastic covers off of one of the bulbs and tried to probe the internal wiring to see if the bulb was getting voltage. Strangely enough, touching any one of six of the eight contact points (there are four "tubes", each with a + and a -) with one probe only caused the LEDs to illuminate. I tried this again with the DMM turned right off, and it still worked.
I figured I was adding some capacitance to the circuit.
Then I exposed the guts of the lamp. There are three circuit boards, one for each bulb, each including a transformer, several power transistors, and inductor, and a bunch of capacitors. I figure this circuitry is all in aid of running the fluorescent bulbs. Furthermore, the tantalum caps look to be darkened - they don't look healthy. I'm wondering whether the LED bulbs (rated at 15 W each) somehow damaged the circuitry (designed for fluorescents, rated at 36 W each). [P = IV. I = P/V. I = 15 W/120 V = 0.125 A. I = 36 W/120 V = 0.3 A. On this basis, it's not like the LED bulbs would draw too much current. Perhaps not enough?]
Given that the LED bulbs are rated for an input of 100 - 277 VAC, I am tempted to bypass the fluorescent circuit boards, wiring the 120 VAC inputs directly to the receptacles for the LED bulbs. (I would keep the ON/OFF switch in the circuit of course.)
There's a simple diagram on each of the LED bulb assemblies, showing an input of 100 - 277 VAC across the L and N terminals.
Does anyone see a downside to this? At this point I could put the two working fluorescent bulbs back in, and run the lamp until they give out, and eat the cost of the new LED bulbs. But at some point they'll give out as well. It might be possible to get new fluorescent bulbs though. But once I start modifying the lamp, it will be hard to go back. Perhaps I should rig up a way to run 120 VAC directly to the prongs on one LED bulb only, to see if it works.
Thanks in advance. I can take photos if this is hard to visualize.
I have a SAD* light which uses three fluorescent bulbs. The bulbs are oddballs, 2G10 type. The light seemed dimmer than usual (it used to be quite bright) and when I opened it up, one of the three bulbs was burnt out. Rather than replace it with another fluorescent, I figured I'd switch over to LED. The 2G10 bulbs are rare, and I couldn't get one locally, but did find them online.
(* The SAD light is used to treat Seasonal Affective Disorder, which is essentially poor mood due to lack of sunlight, unfortunately quite common here during our long dark northern winter.)
Received them today, installed them, and fired up the lamp with the cover off (seven screws to remove the translucent cover, so wanted to make sure I had the bulbs seated correctly). The three new bulbs looked great. So I put the cover back on, and none of the three bulbs would light. Wha ...???
Took the cover off again and tried substituting in the two good fluorescent bulbs. They worked fine, but I could not get more than a flicker out of and of the LED bulbs. There was a mild but definite smell of hot electronics. I wondered if I'd smoked something in either the lamp or the new LED bulbs. Took the plastic covers off of one of the bulbs and tried to probe the internal wiring to see if the bulb was getting voltage. Strangely enough, touching any one of six of the eight contact points (there are four "tubes", each with a + and a -) with one probe only caused the LEDs to illuminate. I tried this again with the DMM turned right off, and it still worked.
I figured I was adding some capacitance to the circuit.
Then I exposed the guts of the lamp. There are three circuit boards, one for each bulb, each including a transformer, several power transistors, and inductor, and a bunch of capacitors. I figure this circuitry is all in aid of running the fluorescent bulbs. Furthermore, the tantalum caps look to be darkened - they don't look healthy. I'm wondering whether the LED bulbs (rated at 15 W each) somehow damaged the circuitry (designed for fluorescents, rated at 36 W each). [P = IV. I = P/V. I = 15 W/120 V = 0.125 A. I = 36 W/120 V = 0.3 A. On this basis, it's not like the LED bulbs would draw too much current. Perhaps not enough?]
Given that the LED bulbs are rated for an input of 100 - 277 VAC, I am tempted to bypass the fluorescent circuit boards, wiring the 120 VAC inputs directly to the receptacles for the LED bulbs. (I would keep the ON/OFF switch in the circuit of course.)
There's a simple diagram on each of the LED bulb assemblies, showing an input of 100 - 277 VAC across the L and N terminals.
Does anyone see a downside to this? At this point I could put the two working fluorescent bulbs back in, and run the lamp until they give out, and eat the cost of the new LED bulbs. But at some point they'll give out as well. It might be possible to get new fluorescent bulbs though. But once I start modifying the lamp, it will be hard to go back. Perhaps I should rig up a way to run 120 VAC directly to the prongs on one LED bulb only, to see if it works.
Thanks in advance. I can take photos if this is hard to visualize.
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