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Workshop LED candle bulb repair

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sideband
(@sideband)
Posts: 4222
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Around 7 years ago, I changed the old CFL's in the living room and dining room to LED's . The light fittings themselves are three-way uplighters and originally were designed to take three 40W tungsten candle bulbs. From the start, I'd used 7W CFL's and when these became difficult to find, I changed them for 3W LED types that had the same light output. These were bought from Sainsburys and have been faultless....until this week when one decided to fail. Actually it was intermittent as gentle flicking would bring it back on for an indeterminate time. Today it once again failed so I decided to take a look at it. 

To cut a long story short, it was nothing more than a classic dry joint. So unscrewed the lamp from the fitting and very easily removed the 'candle' diffuser part leaving me with the LED cluster mounted in the base. Two small Phillips type screws held the assembly in the base and once these were removed it was relatively easy to prise the the assembly from the base. This consisted of the LED cluster, the heatsink and the PCB. As soon as I looked at the PCB, the fault was obvious. Nothing more than a dry joint on the series dropper capacitor.

This was easily sorted (I re-soldered both ends of the capacitor) and reassembled the bulb. Since during disassembly, the LED cluster became separated from the heatsink, I also applied fresh heatsink compound after cleaning off all the old (which was drying out anyway). Once screwed back together, the new compound was nicely distributed between the LED cluster and the heatsink. Refit the 'candle' diffuser, screw the lamp back into the fitting and we are back in business as good as new! 

I wonder just how many of these LED lamps are discarded because of this and simple similar faults?

js1024 759 0772 (2)
js1024 759 0771
js1024 759 0770
js1024 759 0768
js1024 759 0773

The first shows the LED cluster after removal of the 'candle' diffuser (which just unclips), Second shows basic assembly after removal of two small screws, third shows the assembly, the LED cluster, heatsink and PCB. Fourth shows a close-up of the PCB and the dry joint (just to the left of D3), fifth shows the bulb back in action after repair and reassembly.

 

 

 

 

 
Posted : 11/03/2023 7:16 pm
WayneD, Lloyd and PYE625 reacted
sideband
(@sideband)
Posts: 4222
Famed Member Moderator
Topic starter
 

9 months later, same problem, different bulb! Exactly the same procedure as above with the same result!

js1024 759 0918

 Dry joint plainly obvious. 

 
Posted : 02/12/2023 4:22 pm
Lloyd reacted
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