Philips Wiz Tunable White smart lightbulbs - Having trouble with a paired bulb that just flashes white? See how I fixed it, and maybe learn more about the insides of them.

Just a heads up: This is mostly technobabble - if you don't know wtf any of this means, the TL;DR is: I think there's a design/cost-cutting flaw in these bulbs. So if you're within a return/warranty window, just return/exchange/RMA it! But if not, or are curious about what it is, feel free to read on.

Some things I'd like to start with about these bulbs:

• These bulbs use a ESP32 microcomputer for their smart functions - they have TX and RX pads on the daughter board, might be possible to hack these & load your own firmware?
  
• Seemingly they share the same microcomputer for the RGBWW model? - While looking at the board layout, I noted there are pins labelled R, G, B, but they connect to nothing in this tunable white model
• You can't open these bulbs without causing some sort of damage to the shell - good luck if you have no experience fixing otherwise-sealed devices! It may be possible to dissolve the adhesive & as such do very minimal damage, as well as replace the culprit without even removing the driver board from the shell, but again, good luck with that. - EDIT: Actually, if you have enough hand strength, there is a way! But, of course, only if you have enough hand strength to break the adhesive without tools.
  
• The problem appears to be a under-rating filter capacitor on the very end of the power supply to the daughter board with the ESP32 microcomputer - 330μF, only 6.3V. What I think is happening is that a combination of frequent repeated on/off cycles at a lightswitch + excess heat causes this capacitor to fail.

UPDATE - If you're looking to do the same procedure with your own bulb, do also note: 

0. The first-party WiZ Tunable White bulbs are literally the exact same bulb on the inside - I've taken apart both the Philips-branded and WiZ-branded bulbs, every single component inside is identical down to the part numbers, the only differences between them are strictly cosmetic.

1. You do not need to use channel locks if you have enough hand strength! Gently crush in the edge of the bulb where it meets the bell housing, just enough to break the adhesive, working all the way around the perimeter of the bell housing. Then grasp the bell housing VERY tightly as you turn the bulb, and it should be possible to just break it loose & pull the bulb off the bell housing.

2. You don't need to break off the base either! - If your hands are steady enough, you can desolder & remove the old cap, then insert & solder the new cap, without ever removing the driver board from the bell housing.

3. I didn't elaborate much on removing the LED array board - For that, I recommend you grind away the solder on the one soldered connection very carefully with a rotary tool, then using a precision cutting blade to slice through the remaining solder to free the board from that connection. You could instead just heat the solder, but chances are you won't be able to keep that solder melted while prying the LED array board up & out.

So, what prompted this write-up is a oddly consistent issue I've been having with these Philips WiZ tunable white smart bulbs dying, but only in my kitchen - one day they'd quit connecting to Wi-Fi, not power on, and either not light up or randomly flash cool white. 

I've returned/exchanged 3 of them by now, and it just started to annoy me. I absolutely hate just grabbing a new unit off the shelf instead of making at least some attempt to fix it first, but with something like these lightbulbs, I initially thought it was impossible - these are clearly permanently sealed units, never designed to be opened... right?

Which was especially a bummer, as just about every other room in my house has been outfitted with these bulbs & they've worked perfectly, 100% reliably, only having issues whenever my router has issues & even then still working fine with the WiZmote.

By means of having had to replace them more often than incandescent bulbs within 3 months, I managed to end up with a spare one that had the same problem as each one I returned: either it didn't do anything, or blinked cool white. 

I recently had two more bulbs die together, again, in the kitchen - so I got curious. Maybe there is a way to dismantle these & make it usable again, albeit with some damage to the outer shell & some tape/glue holding it together again? And if not, maybe I can figure out why it's happened 4 times now? So I got to it. Below are pictures I've taken during disassembly, some with my smartphone, some with a cheap USB microscope I got as a Christmas gift.

This is the bulb after I removed the plastic bulb top, leaving only the bottom bell housing. I started disassembly by tightening the bulb really hard into a lamp & firmly rocking the bulb side to side, intentionally breaking the base off of the housing. That simply gave me a peek at the internal circuitry, so I then proceeded by using channel locks to clamp on the plastic bulb top, carefully clamping to break the adhesive bond between the housing & the plastic bulb top.

The plastic bulb, separate from the housing. There is a slight lip, you may need to pry on it as well to work the bulb out of the bell housing.

The driver board, with the ESP32 daughter board still attached. Note the bulging capacitor - 6.3v, 330μF. That is the culprit, causing the light to not power on.

Top-down view of the driver board.

Back view of driver board, with readings + closeups of the part numbers on the ICs.

Close-up of the daughter board holding the ESP32 microcomputer - note that there are TX and RX pads that can be soldered to. Chances are you can solder wires to it & get a terminal into the ESP32.

Close-up of the customized ESP32 that is used in the WiZ lightbulbs.

Close up of the defective capacitor - manufactured by Aishi

Now that we're this deep in, here's where things get fun. In my early teens, I had a habit for smashing up old useless electronics before putting them in a electronics recycling bin - in hindsight, that was fucking stupid. But if there's one thing I'm glad I did then, as stupid as it sounds then & even now, I collected the capacitors off of literally all of the PCBs I destroyed. When I dug through my little bag of capacitors that I collected as a kid, I managed to find a 25v 330μF capacitor, only barely larger than the previous one.

I desoldered the old capacitor, then soldered that random spare I had into it. Didn't even think this would fix it, but as I'd later find out, it did.

The capacitor is barely any larger than the old one, yet can handle more than twice the voltage... or claims to, at least.

After soldering in the new capacitor, I put the driver board back into the housing, soldered the wires back onto the base, then reattached the LED array daughter board & resoldered it. Then I tested the bulb.

I didn't fully reassemble the bulb, as I wasn't yet sure if it worked or not - but as you can see here, it powered on! I then checked Home Assistant, and sure enough I had a notification telling me it was discovered on the network & could be set up. The bulb has since been revived, and though I don't know about using it in the kitchen again, let alone using it long term just yet... it seems to be working once more! I've since fully reassembled it, and plan to update this in the future in regards to long-term usage.

So, to recap... (no pun intended) - I fixed a Philips WiZ-Connected Tunable White bulb, and this is how I did it:

1. Carefully yet destructively dismantle the bulb down to the driver board - try to avoid causing structural damage, do as little damage as possible while still freeing the plastic bulb, as well as the base if necessary.
   
2. Check for a blown/bulged capacitor - chances are it'll be the same one as what I replaced here.
3. If the capacitor is blown or bulged, desolder it & prepare a new one, then solder that in. Make sure to trim the leads.
   
4. Put the components back into the bulb, remember to resolder the wires to the base if you had to remove the board to fix it
5. Apply new adhesive, or glue, or whatever, to make sure the bulb doesn't fall apart - Preferably the original thermally conductive adhesive paste, if you can figure/find out what it is. But if not, I'd just use any regular pasty white glue/caulking as their properties are relatively similar.

If any of this helps any fellow tinkerers, lemme know! Not only do I enjoy fixing things, I especially enjoy helping others do so - every device saved from ewaste is yet another middle finger to the tech oligarchy. 

For now though... stay foxy, y'all!