Disassembling Philips Wake-Up HF35xx Main PCB

Step 1

There is a screw under the shiny UL sticker. Remove the sticker or pierce it to unscrew and remove this bottom panel.
There are two tabs holding the panel into the back of the clock/light. If the panel does not come out easily, gently wiggle a flat-blade screwdriver or spudger in the grill next to where the screw was to loosen it.

There is one screw under this tab that's hold the front ring attached in fact. I guess you should have removed it too before prying this ring open

Luuk Akkerman - 06/10/19

That one does not hold the ring but the cover (step 4).

Wozu das denn -

Step 2

Flipping the light on its back will present a small section of the bezel that can be pried out. It is a small plastic strip with hooks that have to be disengaged to be removed.

Flipping the light on its back will present a small section of the bezel that can be pried out. It is a small plastic strip with hooks that have to be disengaged to be removed.
Push the blade of the jimmy directly into the crevice above the cover. Once it has gone a few millimeters, tilt it to lift the cover slightly.
Slide the jimmy to the right side and press it against the latch to release it. Do the same for the left side.
A "jimmy" is essentially a small putty knife with a strong, slightly flexible blade.
Note: Despite the images shown, a spudger is not recommended as the fit is so tight it takes quite a bit of effort to insert and slide.

Getting this section off/out without damaging it is nearly impossible. It’s hooked under the rear rim and it is held down by three clips. I ended up cutting the little bows that connect it to the back and then used pliers on one side to, well, basically break it out…

Adjel van der Meer - 04/10/20

This stage was tricky but by poking a small flat-head screwdriver in alongside the tabs shown in the photo and twisting, I was able to remove it in one piece. Careful studying of of the image above shows where you need to go. Thanks for this excellent guide, I would never have figured this out without it.

Nick Page - 13/12/20

Use a plastic tool or a something like a credit card to get that part out: it won’t break it and it is actually quite easy to remove (same tool used for smartphone)

laurent reichsrath - 18/05/21

Wow, this would have been impossible to do without seeing the pic of the part! I managed to get it free using a tiny flat-head screwdriver to the clip (all three, one by one) and a larger one pushing up on the rim simultaneously.

Tamar Opher -

Thanks also from my side, it would have been an impossible mission without your guide and excellent illustrations. I also succeeded to remove the plastic strip lock with a tiny flat-head screwdriver and a pair of good steel pliers. No damage.

Cesare Liguori -

My model had a screw instead of the clips and was easy to remove. I did use a plastic pryer and think that helped.

Mark van der Staay -

Step 3

We can finally unscrew two more Philips head screws to remove the button ring.
Tip: Lift one end of the ring, tilting it toward the back of the alarm clock. That will get the hooks out from under the rear rim so you can start removing it..

Lift one end of the ring, tilting it toward the back of the alarm clock. That will get the bows out from under the rear rim so you can start removing it..

Adjel van der Meer - 04/10/20

Step 4

Now the six screws holding the front screen need to be removed and the screen can be pulled away to the front.
Take care not to damage the internal screen.

Step 5

Remove the four screws holding the inner screen assembly in place.
Screw organization note for later: these screws have pointed ends

Step 6

There are two tabs that hold the assembly in on the bottom left and right sides.
Using a jimmy — or any flexible, flat, metal tool, such as a putty knife — press the back tabs inwards to release.
Note: Do not be surprised if you have to push hard.
Tip: If you pull the inner screen assembly out slightly, you can see the tabs better. However, it puts pressure on the latches making them more difficult to release.

Need to push quite hard on the tabs, don’t be surprised

totosolat -

Thank you for your comment. I was about to give up, then I read your comment and tried again pushing a little harder and it worked just fine!

Ifelix -

It almost seems like screws are holding it in - but man - the other commenters are right - you realllllly gotta push those tabs in to get it to release. At some point, I was like, "well, if I don't get it open, it's broken anyway, so push really really hard." Worked.

cio -

Wooaw, that was scary but I did it. It really seems that there are additional screws to remove near the tabs, but really it's not the case. There ARE screws, but they don't need to be removed (and they face inwards anyway so they couldn't be removed).

Félix Chénier -

Step 7

Disconnect the speaker from the main circuit board.
The antenna (a long white wire) has a fragile solder connection to the main circuit board and care should be taken to not yank upon it.
Loosen the screw and washer inside the back cover by the speaker and unwrap the antenna wire that was pinned underneath. Pull the antenna all the way through so the back cover can be removed.
Alternately, you may simply pull only some of it through so that the wire is slack enough that the solder joint is at no risk.
Caution: The speaker and the buzzer connectors are the same so be careful when reassembling.

Step 8

The "main PCB" is bottom-most of the circuit boards. It has the power input on it and the voltage regulator which often goes bad.
Remove the three screws at the base of the white plastic holder that is clipped into the main PCB. The circuit board will now lift slightly but be stopped by a ribbon cable.

Step 9

The ribbon cable can be released by pulling forward the tabs on the sides of the connector. Now the circuit board can swing to the side.

Step 10

Unclip the four clips holding the circuit board to the plastic holder.
Be careful as the piezo clicker will still be attached to the holder.

Step 11

Unplug the power connector (brown-red-orange-yellow wires) from the main PCB.
The main PCB is now free to be worked on, but be aware that the FM aerial dangles from a solder connection and can break off.