Sim800l not working on perfboard [SOLVED]

[PCov3r]

Hi everyone,

I am designing an alarm based on a gsm sim800l module and esp32 board.
Everything works very well on a breadboard but not that much on a perfboard.

On breadboard, the gsm module connects without problem. But after soldering it onto the perfboard, the module searches for the network without ever finding it.

I first thought of an interference problem between the esp32 and sim800l. But even with the ESP32 off, I still have the same problem. I then thought that my power supply was not powerful enough for the module, but when I supply the latter outside the case with dupont wires and clamps, the module connects.

I tried everything that came to mind, move the antenna, use another antenna away from the module, look with the oscilloscope for possible voltage drops...
If anyone has any idea...

Thank you!

[J-M-L]

Seems many pins are not soldered - may be interferences there ?
Is the antenna just above the power supply?

[anon57585045]

Antenna might even be contacting the SIM800 RF shield.

However, OP mentioned trying to move it. Double and triple check wiring and solder connections.

Did you use the power supply module with the breadboard test that you said succeeded, or no? If no, the supply itself might not be working at all with this circuit.

[J-M-L]

@anon57585045

Antenna might even be contacting the SIM800 RF shield.

Sure - The antenna should stick out, not be stuck on top of the pins

[anon57585045]

I would be curious about whether it works with an antenna on the uFL connector.

[killzone_kid]

Soldering job looks suspect, I’d double check all joints

[anon57585045]

Yup, I see what looks like at least two cold solder joints.

[PCov3r]

Thank you ! Thank you ! Thank you !
It was indeed due to bad soldering.

I could never have guessed that would cause such an issue.
I am remaking those solder and buying myself a new soldering iron.

Thanks again!