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Default LG touch switch

LG flatron monitor with touch sensor power switch... won't turn on.
Power supply puts out 5VDC OK.
The power -on/off sub board was very dirty. The sensor seems to consist of a odd shaped piece of foam sandwiched in a fold of conductive fabric .
I am looking for a way to fake/ hack the logic of the touch sensor or better still add a physical on/off switch.
From motherboard I get 5VDC, GND, Key0, Key1, BL0, BL1. all but the BL0 and BL1 are passed on to a five button sub-board which makes me think these two are power-on-off related. THere is a six legged IC "S821"and a 3 legged "A0" (SMT= flatfoot devices all) that I associate with the sensing/power part, plus four LEDs for looks, with four resistors.
Any ideas of what kind of tickling could excite this thing?

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Default LG touch switch

On Tuesday, January 16, 2018 at 4:36:40 PM UTC-8, malua mada! wrote:
LG flatron monitor with touch sensor power switch... won't turn on.
Power supply puts out 5VDC OK.


but the LED status doesn't change when you push the button?
Probably there's a trickle power supply and a bigger power supply
that runs backlights and MCU, and anything that inhibits the bigger
power supply looks like 'dead ON/OFF switch'.

Shorted rectifiers and burst capacitors, maybe fuses, are the first things
to hunt for. Low-current finger-sensing gizmo is probably an innocent bystander.
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Default LG touch switch

On Tuesday, January 16, 2018 at 9:32:05 PM UTC-8, whit3rd wrote:
On Tuesday, January 16, 2018 at 4:36:40 PM UTC-8, malua mada! wrote:
LG flatron monitor with touch sensor power switch... won't turn on.
Power supply puts out 5VDC OK.


but the LED status doesn't change when you push the button?
Probably there's a trickle power supply and a bigger power supply
that runs backlights and MCU, and anything that inhibits the bigger
power supply looks like 'dead ON/OFF switch'.

Shorted rectifiers and burst capacitors, maybe fuses, are the first things
to hunt for. Low-current finger-sensing gizmo is probably an innocent bystander.


I agree the 5vdc is some sort of standby. But THERE IS NO BUTTON to push, the sensing gizmo is the only thing to tell the monitor anything powerwise other than (un)plugging the AC cord. And the gizmo is in sorry shape by now.
LG W2361VG
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Default LG touch switch

On 1/17/2018 1:18 PM, malua mada! wrote:
On Tuesday, January 16, 2018 at 9:32:05 PM UTC-8, whit3rd wrote:
On Tuesday, January 16, 2018 at 4:36:40 PM UTC-8, malua mada! wrote:
LG flatron monitor with touch sensor power switch... won't turn on.
Power supply puts out 5VDC OK.


but the LED status doesn't change when you push the button?
Probably there's a trickle power supply and a bigger power supply
that runs backlights and MCU, and anything that inhibits the bigger
power supply looks like 'dead ON/OFF switch'.

Shorted rectifiers and burst capacitors, maybe fuses, are the first things
to hunt for. Low-current finger-sensing gizmo is probably an innocent bystander.


I agree the 5vdc is some sort of standby. But THERE IS NO BUTTON to push, the sensing gizmo is the only thing to tell the monitor anything powerwise other than (un)plugging the AC cord. And the gizmo is in sorry shape by now.
LG W2361VG


Have you tried turning it on with the remote (if it has one)?

Regards,
Tim

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