Humming then dead FB212

[dweezil]

Hi All,
my FB212 (monitor audio sub) has just packed up. It was humming for a few months then got a bit louder and died.
Worth a look inside for a novice with soldering iron and basic meter?
Any pointers appreciated.

 

[yairf]

Here are some hints that apply to KEF PSW subs, but I guess they are nearly the same:

1. Look for Lytic caps (probably 22uF/25V) near the heat sinks of 7815/7915 regs - these caps must be dead.
2. Look for a single cap that activates the relay (possibly 47uF/63V).
3. Check the small transistors near the drivers - take them out and check them individually.

Yair

 

[dweezil]

Thanks for that, gives me somewhere to start!