Help Bypassing Timer on LED Lights

Hi all! I recently purchased some push-lights for my kitchen from my hardware store, and I stupidly didn’t read the package that said that they shut off after 30 mins. This is super inconvenient in my dark kitchen, and I can’t return them. I figured I might as well tinker with them, and any help would be greatly appreciated. The first picture is the small, round push-light (it was in a 3 pack, so I’ve got room for error with these), and the second picture was the even bigger disappointment because it’s a larger strip light.

I found them online for reference here and here. It doesn’t say they shut off in the description of these, but it says it in the user manual under “product guides and documents” for the rectangle light.

TL;DR: Help me bypass the “power saving” mode that shuts these off after 30 mins please!

https://discuss.tchncs.de/pictrs/image/f386ddb6-0c61-47b0-9bcf-095473a000a6.jpeghttps://discuss.tchncs.de/pictrs/image/6cd1d3f5-592f-4238-b401-8c4708ad0901.png

teri,

https://discuss.tchncs.de/pictrs/image/3820e804-d4cd-40d9-8d0f-18788d0ee9af.png

Difficult to find datasheets…

Second picture: To me looks like Q1 (3400) is an NMOS which connects the LEDs to power. The ‘gate’ is marked yellow. It is the ‘control’ input of the MOSFET. The 4 resistors RD RC RB RA (purple) probably limit the current through the LEDs. If you’re lucky, then an easy hack would be to bypass this transistor: Remove Q1 and connect the red and green marks via a mechanical switch. You’d need to scratch away the white coating until you get copper. Then solder wires there. As a consistency check you could measure the voltage over Q1 (red and green marks). Measure once when the module is plugged in but switched off, and once when the LEDs light up. If you see a voltage while the LEDs are dark, then this would partially confirm my guess. As a test: Before removing Q1 you could also try to bypass Q1 with a resistor (~ one, two kOhm) while the LEDs are off. If you see LEDs now lighting dimm, you know that Q1 is the one switching the LEDs.

Other possibility: It might possible that the timeout is computed with an R-C circuit. for 30min you need a rather large resistor because there can’t be very big transistors. R1 (blue) is the largest one. Experiment could be to remove it and see if timeout is still 30min. Or put another 10k resistor in series and see if the timeout gets shorter.

Wondering: What voltage do you connect to the module? Please be extra careful if you have somewhere mains supply voltage.

Susan_B_Good,

'fraid that a little bit of effort producing the circuit diagram from the boards is really needed.

I think that it will show what has to be a microcontroller with an input pad going to the switch and another pad going to a base resistor for q1. Q1 switching power to LEDS via RA - D.

The long light looks to be fitted for a an IR receiver. With U1 near it possibly the decoder. As they show the thing stuck on a rafter presumably way out of reach - I suspect that 's a picture from the version with an IR controller. They have produced a cheaper version, without the sensor and re-used the photos.

Now, if that’s how it is - I’d just remove the microcontroller and glue one of my favs upside down on the board and run wires from its pins to the relevant pads (removing the existing microcontroller). I haven’t bought one recently, but 8 pin ones were costing me less than 50p… Having programmed the replacement with an added option to stay on.

teri,

For the first one: Would be good to know what U1 is exactly. Can you read any number/code on it?

If you are lucky it is simply a ‘switch’ which switches on once you press the button and switches of after 30min. In this case you could add a wire which constantly switches the lights on. Then add a normal mechanical switch to the power supply cables.

If you are unlucky, U1 also regulates the current through the LEDs. Then cannot be easily replaced. Is there anything on the other side?

allmycircuits,

First image: U1 says HZ300 0053, and Q1 says 3400A. The second image has two U1 components: the smaller says RCAKL9 00765, the larger is 6228A 2121/33, and the Q1 is 3400X. There’s nothing on the back of the board.

hardware26,

Can you read what u1 and q1 are in the first image? Q1 looks like a transistor switch and u1 might be a counter. It may be counting a clock or it might be a comparator checking whether a capacitor is charged or discharged to check time. Is there any components on the other side of the board? I would expect a capacitor or oscillator at least for timing.

allmycircuits,

First image: U1 says HZ300 0053, and Q1 says 3400A. There’s nothing on the back of the board. The second image has two U1 components: the smaller says RCAKL9 00765, the larger is 6228A 2121/33, and the Q1 is 3400X.

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