Blown CFL Teardown (Autopsy?)

A relative gave me this CFL, which had started spewing fire one day. Naturally I was curious as to what caused this.

Before we get started – the smell! This thing has the typical “fried electronics” smell, but magnified by 1000. It stunk up my whole garage after being inside for just a day!

Now for the good stuff. Here are some photos of what I found, with a few comments along the way.

The culprit:

The Culprit

 

Looking more closely, we can see a resistor/axial component in the burnt hole:

Resistor Poking Out?

 

After popping the top off, we can see the PCB. It appears that some of the solder joints near the charred section have actually reflowed (or there are a lot of poor solder joints). I suspect this is an indicator of just how hot it got inside here (solder melts near 260°C):

 

We can even see carbon built up on the lid:

Under the Hood

 

After removing the top, and making some precision cuts…

Precision Cutting

 

We’re in! Wow, what a mess:

Yeah, She's Toast

 

Looks like the failure occurred right around the neutral wire connection to the PCB. The main electrolytic is bulging is likely  the cause of the noxious smell. Looks like the film cap blew up as well:

IMG_0874

 

In the bottom-right of the previous picture, you may have noticed what looks like a coil of wire. It looks like (part of) a toroidal inductor/transformer, but the top half the core is missing!

IMG_0878

 

Interestingly, the high-voltage section appears to be fine:

High Voltage Section

 

Inside the base – this is definitely the Neutral wire

Wire Connection To Base

 

Do you have any ideas or comments about this failure? If so, please leave a comment below!

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