Hi there,

I have an e-bike battery charger with a blown capacitor. I replaced the capacitor and after 1/2 hr charging it blew again. Need help trouble-shooting.

Thanks,

Andrew

 

 

Could be anything, really. Start by measuring voltages at various points around the circuit.

 

What should I look for?
Here is me putting in another capacitor.

 

Could it be the square looking thing sitting next to the capacitor over-heating? There is an aluminium heat sink tied to it - you can't see it in the photos as I've removed it to get a look at the capacitor. I put some new thermal paste on it and tried improving the connection to the heat sink. I've also gone ahead and ordered a new charger from China for $12 (sorry Trump).

 

I've also gone ahead and ordered a new charger from China for $12...

It's tough to justify much diagnostic work when a new one is so cheap. If you had a schematic it might be worth a look, but without a schematic I think you made the right choice.

 

Looks like the capacitor is the main smoothing cap for D10 ( twin diode package), so the feedback circuit for the opto-couper isn't working, and the smpsu is giving out full voltage. Measure the voltage across the capacitor.