LED lamp failure analysis – GU10 230VAC 7W

This article is about an inexpensive GU10 230V 7W LED lamp.

Like so much inexpensive Chinese lamp product, it has not markings on the exterior or the lamp (eg voltage, current, power), but the product was sold as 7W and the box had that printed on it.

The lamp failed after less than 100h service, switching on and off intermittently symptomatic of a heat related problem.

Above is the dismantled lamp. Interestingly the LED driver PCB has “Q-3-5*1W” etched into the board, so presumably it is actually a driver for 5 series 1W white LEDs. So much for the claimed 7W, LED product performance claims are often a fraud, more so when the Chinese are involved.

The disconnected LED board was run at 0.3A in free air, and quickly enough began rapidly switching on and off. The problem was on one of the LED chips and almost certainly heat related.

It is not worth repairing these (initial cost was 10 for $25 including shipping from Melbourne), but I was interested in trying to rework the board. The ‘board' is actually a sheet aluminium substrate of about 1mm thickness with insulation layers and copper tracks applied.

Above is the LED board once the LEDs have been removed and board cleaned of flux residue.

A set of 5 1W LEDs were fitted and again tested at 0.3A for hours with no failure. The initial problem was LED failure, cheap Chinese junk. Now the trick is that after positioning the replacement LEDs on solder paste on the board, press the formed plastic lens down to make sure that they are position so they it will properly seat when the LEDs are soldered.

One wonders how much embedded energy there in the discarded product which goes into land fill. In 100 hours, the $2.30 lamp used about $0.20 of electricity, saving perhaps $0.10 over the CFL lamp that it replaced.