Vizio regulator IC question

[danman]

Re: Vizio regulator IC question

Well I don't know how this happened. One of the pads came off the main board. Am I screwed?

[Agent24]

Re: Vizio regulator IC question

Lifted pads are caused by too much heat (are you still using that soldering gun?) or too much physical pressure, or you pulled up the IC while the solder on that pad was not melted.

Since the other pads look OK, it should be fixable if you can find out where that pad connected to and run a wire if needed.

It looks like the pad connected to the via I have pointed out in the photo. If the via is still OK, just run a short piece of wire from the IC leg to the via. If the via is not OK, find where it connects on the other side of the board, and follow the trace until it returns to the top side, then solder a wire from that point to the IC pin.

Might help to carefully clean all the pads with a soft brush and alcohol etc first so you can get a better look at what's going on.

[danman]

Re: Vizio regulator IC question

I'm using a pencil iron I ordered. The other side I soldered perfect. When I got to this other side however the solder started to bridge. When I tried to fix it the solder wouldn't melt. I spent hours trying to get rid of the bridging. No one in this town sells de-soldering wick so i just did my best. After I finally got rid of the bridges that's when I noticed that the pad was gone. I decided to take the chip back off and the pad on the same side on the far left started coming off too. I put it back in place. Is that enough? I'll try connecting the pin to the via like you described. I feel defeated but I don't want to spend $70 on a new main board.

[Agent24]

Re: Vizio regulator IC question

As long as it is still electrically connected to the trace and IC lead, the solder will hold it in place and that will be OK.

Make sure you keep your iron tip clean, that may be the cause of difficulty in melting the solder. Also, adding more flux\solder can help. Once the old flux burns up it does not provide any cleaning action, and may make soldering harder, which is why it should really be cleaned off after each soldering step.

eg: desolder old IC -> wick up old solder -> clean up old flux -> solder new IC -> clean again -> inspect for solder bridges etc

When dealing with SMDs, extra flux and desolder wick are both very useful. You could always order some from Digikey or such.

[danman]

Re: Vizio regulator IC question

Okay so 2 pads came off. I did my best to get some wire attached to the vias. I'm about 90% sure everything is soldered to the board. The tv still won't turn on. I'm probably going to have to buy a new mainboard unless anyone has any other suggestions. Is there a way I can tell if the wires are still connected to the vias? they were moving a bit when soldering. They are solid now.

[Agent24]

Re: Vizio regulator IC question

You can use diode or ohm mode to check between the pins of the IC and the other side of the via on the other side of the board to see if they are connected. You should verify this with all the pins to make sure all of them are OK.

You should also check that they are not shorted to ground or each other as well because that looks like a lot of solder and wire you have used, and if the solder mask has come off underneath they may be shorting to ground or such.

Aside from Pin 4 which is probably ground connection for the IC's power supply anyway.