Geeetech

Hi. To solve the problem, I unsoldered on the antenna socket. Quite difficult but possible. After, I soldered 2 wires : one on the SIM900 pin and the other on the PCB where the antenna was (on one side of the socket). Next, I soldered these wire to the antenna cable : the SIM900 pin to the interior ...

Hello, I had the same problem, I repaired my shield by doing what I say in the "SIM900 - No registration to network" topic. And my shield is working now... You mean your connector was soldered backward? Yes, that's it. I have removed it (but broken it - too small) and soldered wires (look at the ph...

Look at my topic "SIM900 - No registration to network".
I found a solution with a picture...

Hello,
I had the same problem, I repaired my shield by doing what I say in the "SIM900 - No registration to network" topic.
And my shield is working now...

Hello,
My shield is working now !
The antenna connector was not soldered properly. I made some soldering work on my shield and it works now ! I am registered to the network and I can send/receive some SMS.
Here is the problem !
See the picture included in this message.

Hello,
Look at my thread. I have the same problem.
There is a strange thing converning the antenna...

Hello, I have upgraded the firmware as you said to version 1137B03SIM900M64_ST_ENHANCE . The firmware is upgraded but it doesn't work... Here is the result of some AT commands : AT OK AT+CSQ +CSQ: 0,0 OK AT+GSV SIMCOM_Ltd SIMCOM_SIM900 Revision:1137B03SIM900M64_ST_ENHANCE AT+COPS=? +COPS: ,,(0,1,4),...

Hi, First, not sure that 0ohm is normal for the antenna... How can it work if it is 0 ohm ?... Second, concerning the frequency band, please read my first post, I have already tested what you say.... Here is another strange thing : AT+CBAND? +CBAND: INVALID_BAND_MODE,ALL_BAND I think INVALID_BAND_MO...

Hello, I will try what you say. I have already try to do a factory reset of this chip whith the command you say. No result. My question is to know if, according to what ma.seguin said, it is normal that between the two pins of the very small antenna connector located on the board (next to the SIM900...

After verfification, between the 2 pins of the AT1 connector, I have really a short-circuit (0 ohm)... strange. Isn't it ?