原创 Device is not powered on? Replacing the capacitors may help!

Hi! Long time no see! Life has been busy over the past few months...
Students' lives are busy... should be busy... especially for engineering students...

I got an out-of-order ethernet switch, the symptom is that the switch cannot be powered on - no LED lit up, no response at all...
 

Fig. The switch was Level-one's FSW-2421

From previous experiences of many LCD monitors, the capacitors in the power module are getting swollen easily after using for a few years. The capacitances of those capacitor will decrease significanly. Replacing the swollen capacitors may help the monitor to work again...

But for this switch, the capacitors looked good. None of them was swollen.
Anyway, I decided to test all the capacitors in the power module... to just have a try...
 

Fig. Inside the switch (Left: Power module, Right: Main module)

Fig. Using soldering iron to desolder the capacitors
 

Fig. The old capacitors looked good
(from left: 25V470uF, 16V1000uF, 16V1000uF and 10V470uF)
 

Fig. The capacitances of the capacitors
(from left: 25V470uF, 16V1000uF, 16V1000uF and 10V470uF)

Aha! The 10V470uF capacitor had problem! (The capacitance had decreased greatly in percentage!)

After replacing the capacitor, it was working again!!

Fig. The switch could startup normall

P.S. Intended for more durable (to have longer lifetime again), all the 4 capacitors were replaced. Actually there was one another 400V big capacitor, but was not considered...