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Alarm clock that simulates the sunrise. This clock also features a radio and a USB connection. Identifiable by the model number HF3485.

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How to fix the light buttons that not always work properly?

I have a philips wake up light HF3470 and there are 3 buttons to control the light. (brigther, turn it on/off, dimm). Now 50% of the times these work properly. But sometimes when the on/off button is pressed, the light will dimm (as if the button below was pressed), and when the dimm button is pressed, the volume goes up (which is the button below it).

At first I suspected it to be a physical problem that the plastic of one button presses the other a little bit. But I dissassembled the light, and even when pressing the buttons without the white protectors, it still has the same behaviour.

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I'm also having this issue. None of the buttons work at all. Anyone found a solution internally?

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Had same problem.

After going through each of the PCBs it tured out that one of the button fas not working and disturbed the function of the others.

I just removed VOL DOWN and everything started to work (except vol down). Replaced it with a cheap one from ebay and now it's just as new!

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If you opened it completely down to the boards level, then maybe you have noticed that the pushbuttons are no reparable. They must be changed with new. They are not expensive, but you need some skills for de-soldering the existing ones and re-solder the new replacement.

They look like:

http://www2.mouser.com/ProductDetail/TE-...

And the datasheet :

http://www.mouser.com/ds/2/418/NG_CD_157...

says that usually such pushbutton is good up to 1 million operations in normal conditions of temperature, humidity, assuming that is no overpressure or mechanical shock applied.

If you have the skills worth to try it given the fact that the lamp is not cheap, but be ready for surprises as: maybe the wires between pushbuttons board and main board to have some problems or even the integrated circuits on the main board.

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Did somebody Change the Buttons like Victor suggested? Did it help? I habe the same problem. Cheap quality for such an extensive Item.

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I did not need to change the buttons. In my case one of the radio buttons had gotten stuck "depressed" internally. I simply disassembled the light (fairly straight forward), popped off the grey plastic button covers, and pressed the actual button beneath. I also applied some electrical contact cleaner to make sure it doesn't get stuck again. Has been working great ever since.

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Tow of the buttons on my Wake up light are not working / got mixed up in their function: 1) Light up is only changing the clock upwards 2) select + button is selecting the menu, just like the menu instead of changing the clock (instead thats what the light button is doing). …I dismantled everything but can’t find out what is causing this mixed up buttons problem. (not an expert at all in electronics). Any suggestions on what to do?

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I know everyone has likely moved on here but for anyone finding this issue today on the Phillips HF3470..

The buttons are a "right angle pcb mount tactile momentary micro switch" or something like that. 5mm spacing on the switch pins with PCB mounting pins behind at 7mm spacing. I found a 10 pack on ebay. Pacer PTA-116AJ. Made for Motorola. Hopefully these will fit and work better.

You can open of the clock, it's a real PITA to get all the clips to release to separate the bottom from the clock and get at the circuit boards. But it's not impossible esp if you don't care if the outer case gets marred up some.

On my wife's light, the light up/down buttons on the side were not working properly. There are more switches on the main circuit board but they are the same type.

The vertical buttons on the side are on one circuit board as part of a subassembly. The assembly has a wire/molex connector that goes and plugs into the main board with the clock display. Unplug that and this can be pretty easily taken apart to remove the circuit board. Theres some really small c clips on the pivot for the lever. Good luck not losing one when you pop it off. But can probably be substituted with some super glue or something. Rest of it comes apart straight forward after you peel a piece of plastic film off the side to gain access to two screws.

So.. here's the crux of the issue with the button controls on this unit. The micro switches don't each have their own circuit. They are all wired up to a main "loop" with different value resistors between each switch termination to the loop. So then the output from the board is the ground and "data". Each button completes the circuit but with a distinctly different resistance, and therefore voltage drop/or current at the "data" pin. A microcontroller interprets this value into the corresponding function. Sounds like a lovely, spacing saving, material saving design right? Yes, it's great when everything is working properly. The problem is when the switches start to wear out, they start adding some of their own resistance to the the circuit. This renders the function of the button inoperable, or can trigger a completely different function. If you press the switch just right before it's completely shot, the function works, but press it wrong and chaos! hah

Replacing these switches doesn't seem like too bad a proposition if you are an experienced in electronics soldering. The board doesn't have a ton going on. Just be careful not to damage any pads or desolder any of the resistors. If those one comes loose the whole thing is toast unless you can get it replaced. They are VERY tiny. I have yet to try and fix this lamp, the switches are on order. I was thinking of desoldering using a heat gun but I think a wick is a better way to go here with the resistors at risk.

I'll update this after my attempt. If anyone needs pictures let me know and I'll upload some.

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@dhotaling Did you ever end up fixing it?

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Yes I did and it works perfectly again. Recommend using a solder sucker to unsolder the switches. The hardest part is the disassembly/assembly of the whole unit. Not the soldering if you have any experience with that. Good luck!

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