Question PMS-Lite short between 3.3V and not charging cells

[Evilemi]

Hello! I've been having a strange issue. When I was doing analog sticks on my worklog, I noticed a short between 3.3V and ground. I tracked down the short to the PMS-Lite but only if it powers on, then off.
This is a video showing the issue

So far this are things to know:
3.3V are not connected to anything I thought maybe the wii was having the short.
If I turn the battery switch on the pms gets a lil hot.
PMS is not charging the cells.
I get 15V on charge and ground when I plug a PD charger.

This are more pics:

 

[Gman]

Are you measuring the resistance when the PMS has the battery connected? The battery must be disconnected to measure resistance.

Is there a bubble on the BQ chip in the middle? Hard to tell, might just be residue.

 

[Evilemi]

Are you measuring the resistance when the PMS has the battery connected? The battery must be disconnected to measure resistance.

Is there a bubble on the BQ chip in the middle? Hard to tell, might just be residue.

It was voltage to make sure it was on.

I think it's jst residue. If you need more pics I'll post them.

Oh my bad. I thought it had audio. the secon part is continuity. It beeps the first time, but if I turn off the switch, it doesn't beep, and if then I turn on the battery switch it doesn't beep. I'll reupload

 

[Gman]

The way resistance mode works is by putting a very small current between the meter probes and then measuring the voltage from the current. Using R=V/I it calculates the resistance. So you can see that if the battery is connected and there is voltage on the board, you wont get an accurate resistance reading.

 

[Evilemi]

The way resistance mode works is by putting a very small current between the meter probes and then measuring the voltage from the current. Using R=V/I it calculates the resistance. So you can see that if the battery is connected and there is voltage on the board, you wont get an accurate resistance reading.

So If I don't unlpug the battery, I should just have continuity between 3.3v and ground?

 

[Gman]

So If I don't unlpug the battery, I should just have continuity between 3.3v and ground?

I'm not sure, could be depending on the scenario. I'm saying the battery needs to be unplugged to get a reading and there is no point going down the rabbit hole with a not applicable measurement.

 

[Evilemi]

I'm not sure, could be depending on the scenario. I'm saying the battery needs to be unplugged to get a reading and there is no point going down the rabbit hole with a not applicable measurement.

Ok let's unplug the battery. And what should I be looking for, if the pms is not charging the cells?
If connected Charge and ground show 15V. So it is getting current.
Also if I connect the battery the pms get a lil hot, so the cells keep discharging even when the system is turned off

 

[Gman]

Ok let's unplug the battery. And what should I be looking for, if the pms is not charging the cells?
If connected Charge and ground show 15V. So it is getting current

I'm not doubting you, but how do you know the batteries are not charging? You can test this by putting the volt meter on the batteries and when you insert the charger, the battery voltage will raise slightly.

Also with the battery connected, measure the voltage between PW and ground. it should be roughly equal to the battery voltage. If there is no voltage here, or it is significantly less than the battery, there is likely a fault or short somewhere.

 

[Evilemi]

I'm not doubting you, but how do you know the batteries are not charging? You can test this by putting the volt meter on the batteries and when you insert the charger, the battery voltage will raise slightly.

Also with the battery connected, measure the voltage between PW and ground. it should be roughly equal to the battery voltage. If there is no voltage here, or it is significantly less than the battery, there is likely a fault or short somewhere.

Oh don't worry I used to work in tech support and we had to ask questions like that all the time I know they are not charging because I left them charging during the night at 3.6V and now they are 3.41V. The voltage between pw and ground is 3.40V. I have a couple samsung cells. Could try those and see if they charge

 

[Gman]

Oh don't worry I used to work in tech support and we had to ask questions like that all the time I know they are not charging because I left them charging during the night at 3.6V and now they are 3.41V. The voltage between pw and ground is 3.40V. I have a couple samsung cells. Could try those and see if they charge

Hard to say what's going on. Is there a specific area that gets hot when the battery is connected and the pms is turned off? There should not be any heat if it is off and not charging

 

[Evilemi]

Hard to say what's going on. Is there a specific area that gets hot when the battery is connected and the pms is turned off? There should not be any heat if it is off and not charging

2R2 it feels. I'll disconect everything except the batery and PMS-PD.

I changed the batteries for 3.59V. As you can see only the rvl and pms are connected. The pms is cold

So first I'll just connect the batteries, without charging.


Update 2R2 feels a lil hot and the batteries are discharging.

 

[Gman]

2R2 it feels. I'll disconect everything except the batery and PMS-PD

Which part is "2R2"? There isnt a designator with that and it can be hard to decipher the small silkscreen lettering.

 

[Evilemi]

Now I proceed to connect the PD charger

Which part is "2R2"? There isnt a designator with that and it can be hard to decipher the small silkscreen lettering.

Oh sorry. Oh it's definitely the chip next to the battery wire(or that area). SH61SA AE. It gets really hot, can't touch it more than 2 seconds. I might try to take a thermo photo

 

[Evilemi]

Yeah something is not right. the moment I plug the battery the cable gets hot. and the pms start getting warmer unitl I can no longer touch the bottom part near the SH61SA adn BQ chip

 

[Gman]

Disconnect the battery. Measure resistance from B+ to ground and PW to ground.

 

[Evilemi]

Disconnect the battery. Measure resistance from B+ to ground and PW to ground.

Com on ground.
398 on B+
13 on pw. (If continuity it beeps)

 

[Gman]

Com on ground.
398 on B+
13 on pw

Is this with all the wires removed from PMS and PD? Did you always disconnect the battery when you worked on the PMS? And not accidentally poke other circuits with the multimeter with the battery connected?

 

[Evilemi]

Is this with all the wires removed from PMS and PD? Did you always disconnect the battery when you worked on the PMS? And not accidentally poke other circuits with the multimeter with the battery connected?

No I have cables connected
Cables connected:
To PD:
btn.
up.
pwr
charge.
ground

To batteries:
b+
b-
Do you want me to disconect everything?

Not that I can remember

 

[Gman]

No I have cables connected
Cables connected:
To PD:
btn.
up.
pwr
charge.
ground

To batteries:
b+
b-
Do you want me to disconect everything?

Not that I can remember

You should remove all the cables. Also measure 3v3 to ground since that was your initial troubleshooting.

 

[Evilemi]

You should remove all the cables. Also measure 3v3 to ground since that was your initial troubleshooting.

All cables removed

685 - ground to 3.3V
continuity between pwr and ground