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Topic: Gsm Shield doesn't response (Read 3708 times) previous topic - next topic


The first thing I would do is remove the SIM card and see if the unit powers on.  I had a problem with the power supply once using one of these modules and with the SIM card installed it would immediately shutdown every time I turned it on.  The reason being is with the SIM card installed, the unit then tries to register onto the network and will draw upwards of 2 amps of current.  If the power supply can't supply the necessary current the unit will shutdown immediately.

If removing the SIM card makes no difference and your sketch, at a minimum, has the function gsm.TurnOn() being called then your only two options are to call the company or get your hands on a DVM and start taking some voltage readings and checking continuity as cyclegadget said. 

The important things to check will be the power to the GSM chip and the turn on signal from the Arduino to the GSM chip.


thank you for your interst. This days i didn't had so much time for it. I'll try it the next days, i will come up again with the results.

thank you again!


Nov 24, 2011, 04:34 am Last Edit: Nov 24, 2011, 04:39 am by tytower Reason: 1
There seems to be some grey marking to the left of the sim900 unit look along the top line of the capacitor to the right.
Also under that capacitor does not seem the cleanest in soldering


The LED seems to be a purely power indicator LED. I don't think it's connected to any of the SIM900 pin.

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