Hardware Dead Switch IC Replacement

[PIXeL_92]

Hi All,

Recently purchased a dead switch.

No power, doesn't draw a current and battery dead.

Battery is showing 2.73V

I was getting a few shorts on the caps around both M92T36 and BQ24193.

I wasnt getting any input from the USB C port, I fixed this by removing a couple bridges the previous repair person made putting a new one on, now I get 5.17v input and drawing 0.45 and 0.52 amps

So I ordered both chips and the M9 turned up today so I thought I would start with that.

I replaced it and all the shorts have gone from both areas of the board, however I am now not drawing any amps over the charger and the batteries voltage in turn hasn't increased.

I have checked pin 5 of the M9 and I am only getting approx 2v from it and I'm not able to get anything from the capacitor inline with it.

I am 99% sure it has been installed correctly I have taken it back off and on two more times to make sure, each trace has been tinned ever so slightly prior to installation.

Does that mean the new chip is dead or I also need to replace the BQ too ?

Thanks in advance.

 

[TariqSoftDev]

Hi Pixel, I could help you diagnose the board fault via Discord if you'd like as it's faster and an instant messenger.

 

[PIXeL_92]

Hey Tariq, I have discord on my PC will see about installing it on my phone. Cheers

--------------------- MERGED ---------------------------

I have it installed on my phone, what do you need to speak with me ? Sorry I mainly use team speak. Cheers

Hi Pixel, I could help you diagnose the board fault via Discord if you'd like as it's faster and an instant messenger.

 

[TariqSoftDev]

Hey Tariq, I have discord on my PC will see about installing it on my phone. Cheers

--------------------- MERGED ---------------------------

I have it installed on my phone, what do you need to speak with me ? Sorry I mainly use team speak. Cheers

I'll DM you my Discord now.

 

[PIXeL_92]

An update, after @TariqSoftDev has been kind enough to help it looks like I may have some potentially damaged resistors, as I am getting 13v through the Mosfet in but on the outward mosfet I am only getting about 0.2v.

I have included a picture of what he has helped me with, I saw @mattytrog had made the picture so thanks as it helped Tariq narrow down the problem.

Just wondering if anyone else has had a similar issue and was there anything else that contributed to it ?

Thanks again to Tariq, if you need help this guy does good work

 

[mattytrog]

An update, after @TariqSoftDev has been kind enough to help it looks like I may have some potentially damaged resistors, as I am getting 13v through the Mosfet in but on the outward mosfet I am only getting about 0.2v.

I have included a picture of what he has helped me with, I saw @mattytrog had made the picture so thanks as it helped Tariq narrow down the problem.

Just wondering if anyone else has had a similar issue and was there anything else that contributed to it ?

Thanks again to Tariq, if you need help this guy does good work

You need to bear in mind that the 18k and 22k you have marked, you have measured in-circuit. They are in parallel... You will get different readings as resistors in parallel, resistance goes down.

 

[PIXeL_92]

You need to bear in mind that the 18k and 22k you have marked, you have measured in-circuit. They are in parallel... You will get different readings as resistors in parallel, resistance goes down.

Yo, am I going to have to either lift or remove them to get a more accurate reading ? All the others above and below to measure 100k ohms.

Thanks

 

[TariqSoftDev]

Yo, am I going to have to either lift or remove them to get a more accurate reading ? All the others above and below to measure 100k ohms.

Thanks

I've been reading around 50K-80K on them in circuit, 80K fully dis-charged; another person I helped with a repair was similar.

 

[PIXeL_92]

I've been reading around 50K-80K on them in circuit, 80K fully charged; another person I helped with a repair was similar.

Sweet, under load from the official AC @ 13.5v I am getting these readings, they remain the same when I remove the AC adapter and my batter is approx 2.9v. Cheers

 

[mattytrog]

Yo, am I going to have to either lift or remove them to get a more accurate reading ? All the others above and below to measure 100k ohms.

Thanks

Yo, am I going to have to either lift or remove them to get a more accurate reading ? All the others above and below to measure 100k ohms.

Thanks

I wouldn`t lift them. They are very easy to break. They just turn to charcoal if you aren`t careful.

If you are getting 3v3 at pin 6 and between 3 & 6v on pin 5 when plugged into USB, you can assume it is probably OK. For now anyway.

 

[PIXeL_92]

I wouldn`t lift them. They are very easy to break. They just turn to charcoal if you aren`t careful.

If you are getting 3v3 at pin 6 and between 3 & 6v on pin 5 when plugged into USB, you can assume it is probably OK. For now anyway.

As Tariq said he and someone else have tested theirs and are getting a much higher reading of resistance even in circuit.

I am only getting 2v on Pin 5 when plugged in to the AC Adapter, will need to double check pin 6.

I have added a picture and the voltage I am getting over them, the one marked with ? may be wrong as Tariq sent me two pics and I am not at home to double check if it was that point or a point close to it in another picture that was measuring 0.2v (When I get home from work will go over the board again to double check.)

@mattytrog Say these resisters are damaged could it cause the issues I am getting ? What was odd before I replaced the IC I was getting 0.41amps being drawn by the Switch but still no life now I get nothing and all my shorts have now gone around both ICs.

Cheers