How to fix LED with lifted pad?

[dantan]

I was just messing with the lock lights on a keyboard.

I desoldered the LEDs on scroll lock and num lock. But I lifted a pad on caps lock. 

It's all so small, and I don't know how to scrape away the solder mask or whatever.

But I need a caps lock light.

I am wondering if I wire it to the corresponding lead on the scroll lock light, can I use the scroll lock light when I press caps lock? I don't need scroll lock light, so am hoping to find some way to use it from the caps lock.

[TalkingTree]

A picture would help.

[dantan]

some photos that prove how lousy i am.

[TalkingTree]

Put the LED through the hole, solder the negative, whose pad looks still usable to me, and connect the positive (which you lifted) to the SMD resistor (the tiny thing marked 471, in case you don't know).

[dantan]

Put the LED through the hole, solder the negative, whose pad looks still usable to me, and connect the positive (which you lifted) to the SMD resistor (the tiny thing marked 471, in case you don't know).

Thank you, and does the joint of the SMD resistor matter? It seems there are two solder joints and the trace from the positive connects to the joint nearer the LEDs.

At the same time I notice for the three LEDs, the LED in the middle has an SMD resistor not facing the same way.

Sorry for asking silly questions. I just want to understand things better.

[TalkingTree]

and does the joint of the SMD resistor matter? It seems there are two solder joints and the trace from the positive connects to the joint nearer the LEDs.

It has indeed two pads but resistors are not polarized, so you can solder the LED prong to any (not both) of the two. LEDs, otherwise, are polarized and you must respect polarity to install them.

At the same time I notice for the three LEDs, the LED in the middle has an SMD resistor not facing the same way.

It was soldered that way. It doesn't actually matter.

[TalkingTree]

you can solder the LED prong to any of the two.

Actually, not any. Solder it to the pad closest to the LED holes.
Sorry for that.

[dantan]

Thanks for your help, although no success. The LED still does not light up.

[Badwrench]

Thanks for your help, although no success. The LED still does not light up.

Did you put it back in exactly the same way?  Leds must be installed with respect to polarity, they are not reversible.  Try flipping it around. 

[dantan]

Thanks for your help, although no success. The LED still does not light up.

Did you put it back in exactly the same way?  Leds must be installed with respect to polarity, they are not reversible.  Try flipping it around.

I did put it back right and soldered a wire from one SMD to the positive lead (where the pad was lifted). I also tested the led beforehand.

Is there any way to test when I'm just handling this small daughterboard? Otherwise I have to assemble the entire keyboard before I test, which takes time.

Only thing I can think of is to solder that wire to the opposite lead of the SMD. It's all very small and I don't understand how it works so really relying on nice experienced folks like you here!

[TalkingTree]

I did put it back right and soldered a wire from one SMD to the positive lead (where the pad was lifted). I also tested the led beforehand.

The LED orientation is correct. Try soldering the the positive to the closest SMD pad, you need to go through the resistor first.

Is there any way to test when I'm just handling this small daughterboard? Otherwise I have to assemble the entire keyboard before I test, which takes time.

With a tester. Plug the board in and test the negative with the SMD pad. If you get current, you're good.

Only thing I can think of is to solder that wire to the opposite lead of the SMD. It's all very small and I don't understand how it works so really relying on nice experienced folks like you here!

The resistor itself connects the pad and reduces the current flow.