Spontaneous LED bulb teardown — Filamented LED light bulb

I finally was in the mood to tear down one of these filamented LED bulbs.

IMGP11570

IMGP11575

IMGP11572

IMGP11603

There is something in there!

IMGP11582

IMGP11595

IMGP11596

Non-isolated, don’t touch!

IMGP11597

Someone didn’t want to solder!

IMGP11598

Not enough space, shrinking tube will fix it

IMGP11599

0.47R Resistor as fuse

IMGP11601

Capacitive dropper (high voltage)

IMGP11602

Non-isolated driver board: capacitive dropper + bridge rectifier

Filamented-LED-bulb-driver

The LED strips are wired in series in pairs

IMGP11606

IMGP11604

At first I couldn’t make out any individual LED chips, but from a previous investigation I knew that there had to be some.

IMGP11024

Closer inspection revealed bonding wires, at least at the start / end of the strip. Sadly I didn’t manage to excavate individual LED chips.

IMGP11612

There is a hint of a wire

IMGP11613

I didn’t have major issues with the “power supply” with these LED bulbs. No, compared to the dreadful IKEA LED bulbs (not all of them, but many), the power supply worked, but the LEDs themselves were / are not so good.

A few failure modes:

Bad spot welding

IMGP11588

Delamination

IMGP11611

There appear to be at least two types of these LED-strips out there.

The ones I’ve encountered are based on a piece glass + chip-LEDs + phosphorous coating. They are obviously not very fond of bending and too much mechanical stress.

As you can see in the 2nd video (by mikeselectricstuff), there are strips that appear to be based on a more flexible piece of thin metal, some bending is allowed.

Finally, a little info about the power supply

This entry was posted in Electronics. and tagged , , , , . Bookmark the permalink.