Esp32-cam - how to move resistor for external WiFi

I’ve flashed an esp32-cam and it works great except for the WiFi reception. I got a WiFi antenna and mounted it on my camera enclosure. However, I’m absolutely unable to move the resistor required to use the external antenna. I managed to pop the resistor off after much work, but I can’t even get my soldering iron into the other two contacts without touching the ESP32 chip itself.

Is there some trick to this? Do I need a special soldering iron? Do people sell esp32-cam modules with the resistor already in the coax position? None of the tutorials I’ve found actually say how to move this resistor. Thanks.

The best would probably be to use a hot air soldering station. However, I’ve done this by just dropping a hefty glob of solder on top. You just need to connect the two pads. You can also buy the board with external antenna.

Hi, same issue here, and finally decided to buy an espcam board with the external antenna configured (IPEX), 5.85 € + deliver:

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Thanks for the pointer. I didn’t know about hot air reworking stations. Those are just for removing the resistor, right? I did finally manage to remove the resistor myself with a soldering iron and tweezers.

Now the problem I’m having is that the pad for the IPEX connector is even closer to the esp32 chip, so I’m really having a hard time getting anything there. The good news, based on your link (which I’d seen) is that I don’t need to put the resistor back there, I can apparently just bridge the cap with a gob of solder. The bad news is I’m having a really hard time getting the solder to stick in there.

Any suggestions on adding the solder? I assume the hot air soldering station is only for desoldering and would not help with that, but am I mistaken? Maybe I should pre-tin a piece of solid-core wire, try to get it to stick there, and then cut it off with a wire cutter? It’s just so tight in that little corner of the esp32 chip.

A hot air station is also for soldering (reflow), but they can be a lot more expensive than regular soldering irons/stations. I’d recommend going on Youtube and check it out. It’s amazing what you can do with one of those. Lots of flux everywhere :slight_smile:

But other than that, I can only recommend to use a decent soldering iron. I’ve found buying cheap soldering irons will end up giving you nothing but grief. I have a 4 year old mid-range Weller Soldering Station, which still performs really nicely.

I found this, that might help getting the solder to stick:

And yes, a tiny solid-core wire could be helpful in trying to get it connected.

Maybe this could help?

That ^ looks as a good solution and should be marked as such :slight_smile:

Okay, I solved the problem, though don’t know if this is the best way.

Getting the resistor off was messy, but easier. To do that, I first got off some solder by heating up solder wick on top of the resistor. Then I heated it up again and kind of pried off the resistor with tweezers. At that point I lost the tiny resistor.

What I did to bridge the other two points was to use helping hands to hold a piece of solid-core 28 AWG wire across the two points I needed to short. I then heated up the wire with the soldering iron further back, and held the solder against the wire where the points needed to be connected. Finally, after it cooled down, I trimmed the excess wire (the part I’d been heating with the soldering iron) with wire cutters.

The key trick was not to touch the soldering iron to the solder, because then it would just kind of form an enormous drop on the soldering iron. By heating the wire at one point and then melting the solder on the wire about 1cm away, I was able to get the solder to stick to the wire.

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