troubleshooting of produced prototype: nrf9160

[David]

Hello,

I have developed 10pcs of one prototype with the nrf9160 SiP. 

I have some questions regarding some errors im having.

Regarding the SIM 1V8 driver VCC, for UICC interface, I am observing a fluctuation on this channel/voltage, from 0V -> 0.4 VDC, with approximately 1hz frequency.

What can cause this to happend, what is the normal behaviour of this channel when it is short-circuited with ground or something else/similar ?

My second question is regarding the attached image, im observing this on a few of my prototypes, im not able to upload any modem firmware to the SiP, any idea why?

Regards,

David

[David]

Hello again,

I must correct myself: 

David said:

I measure 0 Ohm between sim traces and gnd, when board is power off. Is this normal?

J7 was set to ground.

Thank you for replying so fast, It seems that the main issue now, is the missing 1V8 voltage from the SIM vdd.

I would appreciate it, if your support team could answer me on, what possily  can cause this, maybe firmware related?

Regards, David