Vizio vp322 - excessive current on 5v circuit

[Persist2]

Hello everyone,

I am attempting to repair a Vizio vp322 plasma tv for a friend. (My first foray into TV repair occurred recently when I used YouTube videos to replace capacitors on another friend's LCD TV, and I successfully repaired it.)

Anyway, my friend's plasma TV has been broken down for months. According to his memory, it had the clicking sound for some time, and then it went totally dead.

I replaced two bulging caps on the power board - all the others looked OK. However, the tv was still dead. There was no standby light and no observable response to pressing the tv's power on button.

Then I tested the 5v, 12v, and 16.5v circuits. All showed correct voltages on my multimeter.

Then I discovered a 3A hardwired Littlefuse on the main board was blown. Labeled F3, it was located where the 5v line from the power board enters the main board. I rigged a blade fuse holder with a 3A fuse. The fuse blew when I connected the tv's power cable.

So I decided to check the amps coming from the power board's 5v circuit. It is putting out around 8 amps, so, obviously, this is why that 3A Littlefuse had blown on the main board.

So my question is: In what way could an initial capacitor problem lead to excessive amps on the 5v circuit?

Any help would be greatly appreciated.

Ken

[jetadm123]

Re: Vizio vp322 - excessive current on 5v circuit

If the bad cap(s) was a DC filter cap, then the excessive AC ripple that it's allowing through will cause the components on the 5V rail to work harder and thus overheat and eventually short out.

If the bad cap(s) was used to set frequency, then a change in the capacitance value can affect the frequency, again, causing a mosfet or diode to overheat and short out.

Assuming you replaced the buldged caps, try looking for shorts on the 5V rail using your meter.