Hardware Please help with a Switch Lite Shorting problem!

[renegadeandy]

Hi all.

This is my first post after reading many on these forums - thank you for a great community.

I recently acquired a faulty switch lite. The console will start up, audio, touch screen digitizer and all buttons work okay - I can hear the menu moving around and the switch searching for wifi etc. The problem is, the screen is blank - completely.

The backlight works. The display panel itself has been replaced. The data cable for the screen has been resat many times - and I am confident it isn't a ribbon cable seating issue.

I have started to try to figure out what on the main board itself is going wrong - and opted to begin testing capacitors (mostly at random around where I think the problem can be). I have found some shorts, and some 'nothing' behaviours(4,5,7) which I don't know how to describe - I am not sure what to try next! Your advice would be helpful.

Top side of main board:

Red boxes neither side is grounded
Black boxes both sides grounded

1 -- Both sides are grounded
2 -- Both sides are grounded -- continuity between each side of the capacitor
3 -- Both sides are grounded
4 -- Neither side is grounded

Main board underside:

5 -- Neither side is grounded - there is continuity between the 2 sides of each capacitor
6 -- Both sides are grounded
7 -- Neither side is grounded
8 -- Both sides are grounded
9 -- Both sides are grounded
10 -- Both sides are grounded
11 - Both sides are grounded

Any and all expertise, thoughts and support would be highly useful in my learning on how to debug electronics - and in particular, how the switch lite is operating!

Many thanks in advance.

 

[jkyoho]

Top side of main board:

Red boxes neither side is grounded
Black boxes both sides grounded

1 -- Both sides are grounded
2 -- Both sides are grounded -- continuity between each side of the capacitor
3 -- Both sides are grounded
4 -- Neither side is grounded

1. Normal. 8316 ic LX1 coil goes ground
2. low resistance to ground. Normal since you can hear boots up
3. same as #2
4. Normal lcd data line caps

There should not be any issue on other side since device normal boots up, and all your circled are main power line coils and CPU caps.

-------------
When you say backlight works, do you see 17v on backlight cable or you see backlight light up?
Have you check any bent pin inside LCD connector? Have you tried cleaning up the flux around lcd connector?

 

[renegadeandy]

1. Normal. 8316 ic LX1 coil goes ground
2. low resistance to ground. Normal since you can hear boots up
3. same as #2
4. Normal lcd data line caps

There should not be any issue on other side since device normal boots up, and all your circled are main power line coils and CPU caps.

-------------
When you say backlight works, do you see 17v on backlight cable or you see backlight light up?
Have you check any bent pin inside LCD connector? Have you tried cleaning up the flux around lcd connector?

Very interesting - thank you.

I see the backlight light up.

The pattern is :

1/Backlight goes on for around 1 second
2/Backlight goes off for around 1 second
3/Backlight stays on and i can hear normal operation

I thought perhaps one of the pins was slightly bent and i pushed it back into it's natural space. This is how the connector looks now:

How does that look against a new condition connector? The display still shows nothing.

 

[jkyoho]

I would check diode value reading and compared to this post.
https://gbatemp.net/threads/nintendo-switch-and-nintendo-switch-lite-diode-measurements.564536/

 

[renegadeandy]

Apologies - I updated my previous post - please see the image i attached.

I actually have not done a 'diode value reading' before. I assume I go between the pin and ground? With the battery out?

 

[jkyoho]

Apologies - I updated my previous post - please see the image i attached.

I actually have not done a 'diode value reading' before. I assume I go between the pin and ground? With the battery out?

red prob to ground, black prob to the component to be tested. Check youtube to see how multimeter set to diode mode

 

[renegadeandy]

Okay! Interesting.

Your image showed FPC3 -- whereas I think we are dealing with FPC5 (I may be wrong).

I did the diode test for FPC5 and this shows:

As you can see -- all the expected voltage drops are slightly lower than the recorded 'goods'.

The biggest difference was the 1.647 on the right rail - which was OL for me.

Also the grounds on pins 9 and 10 seemed to not have continuity.

Doing a bit more digging, Following pin 8 on the right through to the left of the image above - and to the underside of the board it reaches the red circle pad:

Unfortunately, I don't know what I am looking at here, or where to go from there! I think the black chip at the top of the above picture is a power management ICU - perhaps something is wrong around this?

I have a niggly feeling that the ribbon cable is damaged leading to the display -- the previous owner claimed to have replaced the screen - but can you please offer an opinion on the ribbon cable? The black sections on the traces look odd to me...but may be completely normal:

 

[renegadeandy]

<bump>

 

[Nagaa]

Try to replace the MAX77620, i fixed a switch lite with the same issue

 

[renegadeandy]

Hi Nagaa, ooo a new lead! This has me wondering, I am not next to the device to check myself (I will later), but, is the MAX77620 the chip in the middle picture of my previous post? If that is the case, it lines up with my lack of getting a good reading on the diode test on the trace which leads up to this exact chip!

 

[Nagaa]

Hi Nagaa, ooo a new lead! This has me wondering, I am not next to the device to check myself (I will later), but, is the MAX77620 the chip in the middle picture of my previous post? If that is the case, it lines up with my lack of getting a good reading on the diode test on the trace which leads up to this exact chip!

Yep this is exactly this chip, i have a spare motherboard i can take some measurement tomorrow if you need

 

[renegadeandy]

Yep this is exactly this chip, i have a spare motherboard i can take some measurement tomorrow if you need

That would be great if you could, it could let me verify normal against what I am seeing! Thank you! I await your update!

 

[renegadeandy]

Nagaa, can you help with those measurements?

 

[renegadeandy]

<bump>.

Also in the video above he replaces the FPC connector for the LCD ribbon before doing the MAX77620H. I think i will also need to do this - but he seems to suggest he heats the underside of the board to do this connector. Presumably because any other way and you melt the plastic. Are you not a risk of desoldering the chips which are on the underside directly under neath with this method? Not sure of the best way to resolder the replacement FPC when it arrives.... Thoughts and advice please.

 

[renegadeandy]

Can I get some advice on this?