Hardware Black Screen issue after replacing BQ Chip

[PIXeL_92]

Hi All,

I bought a faulty switch that had a cracked screen and also didn't turn on.

Opened it up to check for short and to transplant it into a housing that had a good LCD etc.

All the caps around the BQ and some around the M9 chip had shorted, checking with a voltmeter it wasn't drawing any current so I removed the BQ chip and all the shorts went away, so I installed a new BQ chip.

It started charging at 0.52a and the battery icon appeared on the screen so I thought I had fixed it left it to charge a bit but then the icon disappeared but it was still drawing a current. I turned it on and the Nintendo logo showed on the screen but then nothing and it stopped drawing a charge, checking the BQ chip it had shorted again.

So took a known working chip and installed it, there was again signs of life and was getting the voltages I was expecting around the two ICs. The charge icon showed again and the battery was fully charged it would start charging at 2.2a.

Turned it on and again the charge icon appeared and the Nintendo logo but then again it turned off but no shorts around the BQ chip this time and it still draws current.

I think it is turning on but the Backlight and LCD are not turning on as when I leave it for a few minutes the CPU does get warm and when placing it in the dock it does detect it but no signal to the screen.

So I checked for shorted caps around the Backlight and LCD connector and the ones circled in the picture are all shorting.

Has anyone experienced an issue like this before because I haven't and I'm struggling to find the cause.

Thanks

 

[PIXeL_92]

Was just checking voltages I'm getting 4v to the Backlight ribbon but it's not lighting up.

 

[Ttm3]

Was just checking voltages I'm getting 4v to the Backlight ribbon but it's not lighting up.

See if you can get it into hekate. If so check battery stats.

 

[PIXeL_92]

Tried two batteries one known to be working

 

[Ttm3]

Tried two batteries one known to be working

Can you boot into hekate?

 

[SheriffBuck]

Was just checking voltages I'm getting 4v to the Backlight ribbon but it's not lighting up.

4v isn't enough to drive the backlight. That's either backlight "off" or there is a fault. You should expect 17v here.

Sorry if this sounds offensive, but some of the items circled are inductors and will test as shorted. You may only have been talking about caps, but wanted to double check.

You don't think the short is on VSys? It certainly feeds the MAX77621 you've circled which drives the GPU. There is a circular test pad in the lower left corner of the MAX77620 PMIC.

Sheriff

Sent from my SM-G975F using Tapatalk

 

[PIXeL_92]

Can you boot into hekate?

Not got into the software side of things will have a look in the morning.

Thanks

4v isn't enough to drive the backlight. That's either backlight "off" or there is a fault. You should expect 17v here.

Sorry if this sounds offensive, but some of the items circled are inductors and will test as shorted. You may only have been talking about caps, but wanted to double check.

You don't think the short is on VSys? It certainly feeds the MAX77621 you've circled which drives the GPU. There is a circular test pad in the lower left corner of the MAX77620 PMIC.

Sheriff

Sent from my SM-G975F using Tapatalk

Yeah when I had it under the lamp today I noticed the colour difference between the two and realised they weren't in fact caps.

However lifting the board back out, I checked a few of the caps on the rear under the CPU and a few are shorted.

I have put it back together as I had other bits to repair when I put it back together it would try and boot as the fan would spin up a few seconds at a time then go full blast got a few more seconds. So for now I have disconnected the battery.

Thanks

 

[Ttm3]

4v isn't enough to drive the backlight. That's either backlight "off" or there is a fault. You should expect 17v here.

Sorry if this sounds offensive, but some of the items circled are inductors and will test as shorted. You may only have been talking about caps, but wanted to double check.

You don't think the short is on VSys? It certainly feeds the MAX77621 you've circled which drives the GPU. There is a circular test pad in the lower left corner of the MAX77620 PMIC.

Sheriff

Sent from my SM-G975F using Tapatalk

Not got into the software side of things will have a look in the morning.

Thanks



Yeah when I had it under the lamp today I noticed the colour difference between the two and realised they weren't in fact caps.

However lifting the board back out, I checked a few of the caps on the rear under the CPU and a few are shorted.

I have put it back together as I had other bits to repair when I put it back together it would try and boot as the fan would spin up a few seconds at a time then go full blast got a few more seconds. So for now I have disconnected the battery.

Thanks

When you say they are shorted what are the ohms you're reading to ground? Is that with the battery & charger disconnected?

 

[PIXeL_92]

When you say they are shorted what are the ohms you're reading to ground? Is that with the battery & charger disconnected?

I will need to check, I gave up for a bit with it as I had other things to repair, will take a look tomorrow.

I have noticed that the following happens.

Connect via a USB hub to charge it takes 0.5a
Battery logo shows and doesn't seem to charge and as soon as I remove power it dies
Put a working battery in and it takes 0.5a
Press on button
Nintendo logo shows and then goes black
It won't turn on again till you either remove the battery or hard reset it, then it gets as far as the Nintendo logo

Cheers