Dell Inspiron 1720 Repair

Today a Dell Inspiron 1720 came in with the following symptoms

• Completely Dead.

No life, no light, no fan, nothing. Zip. Nada.

Instead of ordering a new mainboard, I felt like a challenge so I started troubleshooting. The first thing I noticed was that every time the AC adapter was plugged in, the LED would go out straight away. This cheered me up, as it indicated a short on mainboard somewhere, and this type of problem is fairly simple to repair.

I removed the mainboard & connected it to the bench power supply. Yep, definitely a short as the power supply LCD registered maximum amps. Voltage drops down, amps go up.

It took me 5 minutes to find the short. It was on the underside of the board and it could be located through visual inspection. The area is marked in red.


Here is a closeup, you can see the damage to capacitor PC123


The capacitor is 10uF & is part of a power circuit called a VRM - Voltage Regulator Module. Its a multiphase DC-DC buck converter which steps down the main line voltage (19.5V) down to a level required by other circuits. This one I think is for the CPU (1.075V).

I stripped a 10uF capacitor off a scrap board.


I removed the remnants of the old capacitor & plugged in the bench power supply. Current draw was now perfectly normal. I soldered the new capacitor in.

And fired it up.


Problem solved!!!