Privacy question - is GPS active with phone powered off?

[bokomaru]

I want to say the modem actually isn't powered while the PinePhone is turned off.

Confirmed.

Can't say if I'm right, but somebody could verify this with a multimeter.

I did it.

So I must've read the schematics well enough to come up with the correct conclusion here.

To verify: Take apart a PinePhone. Maybe just need to remove the second plastic cover with the screws in it?

Nope! Those pins aren't exposed, even if it looked like they were in a photo. I even took the metal cover off the modem, no good. Here's what I did instead...

I tore apart a PinePhone. Had to unplug all the connectors and remove the mainboard, then remove the big metal plate covering up everything on the back side.

I identified some big components in the schematics which connect to VBAT_BB. I picked C1502 and C1506. I found those in the "PinePhone mainboard bottom placement v1.1" drawing. C1502 and C1506 are the big capacitors right next to the battery connector.

Obviously, it's not as easy to power up this mainboard without the rest of the phone attached. But it's easy enough for me to just hold the battery terminals up to the battery connector. So that's what I did.

To confirm battery contact, I measured the voltage between ground and the VBAT test point next to the battery connector (other side on the front face). I got around 4.1 V, since my battery was mostly full.

Now, without the battery connected, I used my multimeter's "connectivity" function across each of those big capacitors to give them a little charge. I switched back to voltage measurement mode and verified that I could read almost 1.0 V before the capacitor discharged through my multimeter. Cool, so I've confirmed that if the capacitors are charged, I'll be able see it.

Next, I repeated the "connectivity" test, but before measuring the voltage across the capacitors, I attached the battery. The voltage is 0.0 V. This implies that not only is the modem not being powered, but its VBAT_BB is actually grounded I guess.

Repeated this test while the modem killswitch was in the "on" position. Same result.

It's either on or it's off, right? Then we'll really know.

It's off.

Hope that gives everyone some confidence. If you would like me to measure something else, ask me before I put this thing back together. :-)

Even better, I hope someone else tries it too. Don't just take my word for it. ;-)

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Why? I think there's a lot of power going through Q1500. I guess it requires two levels of gates. Ask a hardware developer.

Nah, it's probably an inverter. So for PL7-4G-PWR-BAT, "high" means "on". With only one transistor there, "low" would mean "on".