Remove capacitive switch

[Hvdflorida]

Hi, I have a light that uses what I think is a capacitive sensor to turn on and off the light. My problem with this is that it defaults to Off when plugged in and I need it to either default to On or always be on when power is provided.

 

How can I bypass the capacitive button?

its that big metal disc.

 

 

[Bananasplit_00]

a pice of antistatic bag, or aluminum foil and some tape maybe? just tape it on there and see what happens

[Hvdflorida]

1 minute ago, Bananasplit_00 said:

a pice of antistatic bag, or aluminum foil and some tape maybe? just tape it on there and see what happens

Tried that, doesn’t work.

[iamdarkyoshi]

Try connecting the metal disk to ground. This should work assuming that it powers on if you hold your finger on it during power on

 

If not, what ICs are on the board?

[Hvdflorida]

5 minutes ago, iamdarkyoshi said:

Try connecting the metal disk to ground. This should work assuming that it powers on if you hold your finger on it during power on

 

If not, what ICs are on the board?

I just tried that actually. Doesn’t do anything when I put some wire touching the disc to the ground. Still turns on when I touch either the wire or the disc.

 

Heres a closer shot of the pcb around the disc. To the right look like more resistors and I think the big one is the led driver. The other side show nothing but the leds.

[iamdarkyoshi]

7 minutes ago, Hvdflorida said:

I just tried that actually. Doesn’t do anything when I put some wire touching the disc to the ground. Still turns on when I touch either the wire or the disc.

 

Heres a closer shot of the pcb around the disc. To the right look like more resistors and I think the big one is the led driver. The other side show nothing but the leds.

 

U2 appears to be an all in one solution

Your lamp is probabky similar to this schematic:

 

Desolder the chip and link the pads for pin 1 and pin 5 together, assuming there's a resistor going from pin 1 to the transistor

 

This should turn the transistor that controls the LEDs on

[Hvdflorida]

15 minutes ago, iamdarkyoshi said:

U2 appears to be an all in one solution

Your lamp is probabky similar to this schematic:

 

Desolder the chip and link the pads for pin 1 and pin 5 together, assuming there's a resistor going from pin 1 to the transistor

 

This should turn the transistor that controls the LEDs on

Without desoldering it I tried connecting 1 to 5 on U2 and the light turned on!

 

Could I just leave it there and connect 1 and 5?

[iamdarkyoshi]

6 minutes ago, Hvdflorida said:

Without desoldering it I tried connecting 1 to 5 on U2 and the light turned on!

 

Could I just leave it there and connect 1 and 5?

Probably would be fine.

[Unimportant]

27 minutes ago, Hvdflorida said:

Without desoldering it I tried connecting 1 to 5 on U2 and the light turned on!

 

Could I just leave it there and connect 1 and 5?

Probably killed the chip's output if it's a push pull output (cant find a datasheet), creating a short circuit when the chip is driving it's output low and you had that output wired to vcc. But it's done now and should keep working fine, just don't expect to undo it now.

[Unimportant]

48 minutes ago, iamdarkyoshi said:

... assuming there's a resistor going from pin 1 to the transistor

Looks like a mosfet to me anyway (60N03)

[Hvdflorida]

3 minutes ago, Unimportant said:

Probably killed the chip's output if it's a push pull output (cant find a datasheet), creating a short circuit when the chip is driving it's output low and you had that output wired to vcc. But it's done now and should keep working fine, just don't expect to undo it now.

That’s interesting. Yes when I temporarily hardwired 1 and 5 without desoldering the chip, and I removed the wire I was holding to it, the light stayed on, and when I touched the disc it did not turn off. Only after unplugging the power and then plugging it back in did the capacitive function work. TBH if it had fried the chip and stayed on forever then I’d be happier as I wouldn’t have to solder a connection from 1 to 5 myself lol.

[Unimportant]

1 minute ago, Hvdflorida said:

That’s interesting. Yes when I temporarily hardwired 1 and 5 without desoldering the chip, and I removed the wire I was holding to it, the light stayed on, and when I touched the disc it did not turn off. Only after unplugging the power and then plugging it back in did the capacitive function work. TBH if it had fried the chip and stayed on forever then I’d be happier as I wouldn’t have to solder a connection from 1 to 5 myself lol.

I'd have removed resistor R14 and solder a wire from the FET's gate to VCC. Bigger parts which are easier to solder and easily undone.

[iamdarkyoshi]

4 minutes ago, Unimportant said:

I'd have removed resistor R14 and solder a wire from the FET's gate to VCC. Bigger parts which are easier to solder and easily undone.

Or just jump the transistor/fet lol

[Unimportant]

14 minutes ago, iamdarkyoshi said:

Or just jump the transistor/fet lol

Removing a TO-252 without the correct equipment/expertise might damage the board tough. A little smd resistor can be snipped in half with cutters and then easily remove each side with one swipe of the iron.

 

Thats my lazy way of doing things anyway.

 

EDIT: I misread remove in stead of jump. Yes, that would be simpler still, guess I'm not yet lazy enough.