HOWTO Check Pi-Top receiving power?

[julianbrooks]

Hello,
Our Pi-Top3 shows a red light (1 flash, approx 1s) when the mains is attached.

After minimal use over last few months, thought be good to fire it up again.
We had to change the Hub prior to stopping use - am wondering if it’s not receiving charge (can I have not connected something properly when changing the Hub?).
It did boot for about 10 minutes when 1st turning it on today. I was busy setting up ssh settings, but did see there was a ‘your pi will shutdown soon unless connecting to mains’ type message but as it was already plugged in, I didn’t pay it any attention…
This is why I’m now wondering whether it’s just been running on battery power since I replaced the Hub (it’s only been turned on 3 times over the last 3 months).

Wisdom/guidance/insight much appreciated.

All the best,

J

p.s. to be clear - it wont boot atm
p.p.s. - it’s not the mains plug, have multimeter’d it and working fine

[duwudi]

@julianbrooks since the mains charger is not powering the device by itself that can only be a hub problem, so it sounds like you’ll need to replace that again as there is a possibility of damaging the hub if done incorrectly. The most difficult part is the wide FFC cable that goes from the black FPCB to the hub - if you connect that whilst the battery is live then there is a chance of shorting high voltage pins to low voltage ones or even ground.

Ideally, you should disconnect the battery first (there’s an 8-pin connector from the black FPCB that goes into the battery port), connect the wide FFC cable to the hub, then reconnect the battery again.

[julianbrooks]

Hi @duwudi, many thanks for quick response.
Are you saying we need another Hub or can try out your suggestion with what we have?

Also would appreciate more info on how to access and disconnect the battery, as per your suggestion.

Thanks again

[duwudi]

@julianbrooks could you send some photos of your installation? Including all cables attached to the hub. Upoin further reflection maybe there is a bad connection somewhere that is causing the power supply to short to ground and thus not charging the battery or powering the device

[julianbrooks]

No worries @duwudi, give me a shout if you require more images (& of what:). Cheers, J

[duwudi]

@julianbrooks thanks for the images, everything looks pretty good! If you have a multimeter can you check these voltages for me when you plug in a power supply:

So put the black probe on the GND (the gold pad beneath the screws) then place the red probe on V1 and tell me the voltage, then again on V2. I want to check if the power supply is ok and also if this fuse is blocking current due to a short circuit somewhere.

[julianbrooks]

Hey @duwudi,
0.00 at V1 & V2
18.54 when connecting red to back of power connector, NW of V1 arrow tip (in image) .

Presume not good - now what?

[duwudi]

@julianbrooks are you sure you get zero at V1? That’s the exact same voltage as the central pin of the power connector so it should be reading the same value. If you get ~18V at v1 and 0v at v2 then we can assume it’s probably a short circuit on the hub and that would need to be replaced. However, if both v1 and v2 are 0V then we should replace the power adapter first

[julianbrooks]

Hey @duwudi,
Yes, definitely 0 at V1 (checked it like 10 times, the other day:).
Just so we’re clear on terminology, more for my own benefit than anything else…:
The power adaptor (wall-wart, mains plug etc), shows 18.54 on central tip.
The power connector socket (part of Hub), also shows 18.54 when connecting red tip to rear of socket, directly north west of [V1] in above image.
I’m up for doing whatever’s required to sort this out though.
Thanks again for your continuing engagement,
J

[duwudi]

Ok, that had me quite confused for a while but I think I’ve figured it out. Not sure how this has happened but there seems to be no solder in these two joints for the DC connector

Usually, this would have no chance of passing visual inspection, but hey, you must be a one-in-a-million customer Since we use automated pogo pin testers for powering the device for electrical validation it makes sense that this wasn’t caught if it passed visual inspection, we just power it over pogo pins and run all of our diagnostics from those (you can see these small circular pads below where I’ve put a red box). If you have a soldering iron it will be really easy to fix (let me know if you want to jump on a call to go through that), if not just send it back and we’ll get you a free replacement

[julianbrooks]

@duwudi

you must be a one-in-a-million customer

Lol. Lucky us
Nice spot @duwudi.
I’m out rest of day now but will have a go later.
I’ve recently bought a soldering iron but am very noob with it, would appreciate a quick walkthrough of what’s required (dm maybe?) if you wouldn’t mind.
If I mess it up will you replace anyway?
I’m happy to send it back if needs be but equally if it’s reasonably trivial then I may as well have a go eh…
Cheers, J

[duwudi]

@julianbrooks that’s the spirit! Yeah if you mess it up we’ll replace it anyway, but I think you’ll be fine

[julianbrooks]

Ok, done.
Whoop whoop victory!
After looking at couple of other joints on the board, they could prolly do with bit more solder but was wary of the component next to one of the holes. Anyhow - it works. Awesome.

Many thanks @duwudi - you’ve been great

[julianbrooks]

Actually, now wondering if I’ve spoke too soon.
After powering down and removing the wallwart connection the Hub green light remains and the pi has a redlight (off but receiving charge). Presume this will just drain the battery…
Is this my dodgy soldering @duwudi or something else?

[duwudi]

@julianbrooks are you running pi-topOS? It sounds like you have shut down the Raspberry Pi but the pi-top hardware doesn’t know to cut the power so the lights remain on

[julianbrooks]

Yep - most recent pi-topOS - updated yesterday.

[julianbrooks]

Apologies in advance for pestering @duwudi (or anyone who might have any suggestions) but can I bump this please…

[duwudi]

@julianbrooks apologies for the slow response, this is quite a hard one to debug so I didn’t respond straight away and then forgot to reply!

Can you run i2cdetect -y 1 just to check you are detecting the hub MCU?

Also, could you measure the voltage of this pin before and after shutting down:

Basically, if this pin is being controlled correctly yet the hardware is still letting power through then we know that it must be a hardware problem.