[SOLVED] Help required with SIM 908

[rajuroshan]

Hello all ,

I have two SIM 908 modules:

module one firmware 1137B03SIM908M64_ST

module two firmware 1137B04SIM908M64_ST

Ok now i have two SIM cards 900mhz and 1800mhz

Both SIM card works on module one perfectly

On module two I Don't get network for sim card 1800 mhz ...900 mhz works fine.

Any ideas ...

Things done till now :

I have checked on other B04 frimware modules ... same problem .....

Swapped firmware same issue....

checked AT+CBAND

Power is supplied from LM2576

Help required.

.............................. Ok found out more info

The SIM vdd of module two

with Sim card 1800 mhz the voltage goes to 2.94 stays there for a while then drops to zero

with Sim card 900 mhz the voltage goes to 2.94 stays there forever.

.............................................

Ok one more thing i found out the SIM_VDD voltage goes to zero as soon as the SIM 908 gets on network...

This is driving me crazy ...... happens only on B04 firmware. and a specific sim 1800 mhz

can someone tell me how to retrieve the firmware from my B03 device... wanna swap the firmware...

already tried downloaded B03 and it does not work.

Thanks in advance.

 

[vikasdabas]

Could You Find the reasons for this.
We are also encountering the similar problem, wherein the SIM900 would stop providing VDD to Simcard in case GSM signal level is little lower.