Tab S2 display wont turn on after battery/LCD/USB port replacement?

[Silent Silent]

Hi

I had a crached screen and faulty charging port on my 9.7" tab S2, so I changed out the parts along with a new battery. Now the display wont turn on. The menu and back buttons light up at the bottom, but the device refuses to show a display. The only thing I get is occassionally randon bright split second flashes on light come up on the device.

Ive tried replacing the LCD to motherboard flex cable and all button combinations, but the device flat our refuses to display normally.

Can anyone help please?

Thanks

 

[mustang7757]

[Merged duplicates]

 

[mustang7757]

Hi welcome to AC!
If you did the work yourself , double check everything again .

 

[Silent Silent]

I double checked all connections everything seems fine?

 

[mustang7757]

I double checked all connections everything seems fine?

Maybe look on YouTube teardown on your device see if u spot anything otherwise its a defective screen

 

[Silent Silent]

The screen is new though, and the old one still worked albeit it was cracked. That one refuses to display too other than the random bright flashes of light.

Its as if the display is not connected to the motherboard properly or there is some fault in the connection given the random screen flashes?

 

[mustang7757]

The screen is new though, and the old one still worked albeit it was cracked. That one refuses to display too other than the random bright flashes of light.

Its as if the display is not connected to the motherboard properly or there is some fault in the connection given the random screen flashes?

I understand but even new things can be defective, so triple check your work and if don't see anything call up where you bought it from.

 

[Silent Silent]

I double checked now and cant see anything. The old display doesnt work either. Any ideas what would cause the display to completely not work like this?

 

[mustang7757]

I double checked now and cant see anything. The old display doesnt work either. Any ideas what would cause the display to completely not work like this?

If old display doesn't work as you mentioned it did with smashed screen then something on your end didn't do correctly, let a repair center look at it if you can't find whats wrong .

 

[blackhawkhot]

I double checked now and cant see anything. The old display doesnt work either. Any ideas what would cause the display to completely not work like this?

There may be more damage from the initial incident you didn't spot...

&

ESD. Especially if it' was dry. When components are loose as opposed to being in the circuit the ESD sensitive ones can be easily damaged. A stick of RAM is a good example, very ESD sensitive.
If you can see, hear or feel a static charge it's already more than enough to cause damage...

 

[Silent Silent]

Let me clarify sorry. The tablet had a cracked screen before I bought it second hand. It worked for months then the usb port fell apart so it needed replacing. So I changed battery and charge port. Then when I went to plug the old screen in it was flashing like red, green but I could see the charging icon. After I removed the screen and checked the LCD flex cable it's just doing random bright flashes of light now.

Could I replace the T813 motherboard with a T819 version?

 

[blackhawkhot]

Let me clarify sorry. The tablet had a cracked screen before I bought it second hand. It worked for months then the usb port fell apart so it needed replacing. So I changed battery and charge port. Then when I went to plug the old screen in it was flashing like red, green but I could see the charging icon. After I removed the screen and checked the LCD flex cable it's just doing random bright flashes of light now.

Could I replace the T813 motherboard with a T819 version?

What you need is some "known good" parts. Repair shops keep these to aid in troubleshooting.
mustang7757 is correct; the new LCD could be defective.

Did you try the old LCD (it was still working, right?).

Sure the cable/connectors are good?

 

[Silent Silent]

I've tried a new motherboard and it's still doing the same thing. Screen flash on and off and that's all I'm getting. I don't understand the battery and usb port are brand new. But when it's charging with the screen disconnected the battery doesn't even get warm and neither does the chargeelr plug. Surely the plug should be warm if it's charging properly?

 

[blackhawkhot]

I've tried a new motherboard and it's still doing the same thing. Screen flash on and off and that's all I'm getting. I don't understand the battery and usb port are brand new. But when it's charging with the screen disconnected the battery doesn't even get warm and neither does the chargeelr plug. Surely the plug should be warm if it's charging properly?

Use a DVM to check V+
You can get a basic DVM cheap.

 

[Silent Silent]

Do you mean a digital multimeter? If so I've got one of those. How would I use it?

 

[blackhawkhot]

Do you mean a digital multimeter? If so I've got one of those. How would I use it?

Yes.
Use the ground plane (wide portions of the PCB generally) black wire (usually, if any) to the hot lead V+ coming off the charger port, (red wire if any, usually).
Don't short it!
Nominal voltage is 4-5 volts before mobo regulators, I believe.

 

[Silent Silent]

After being plugged in the motherboard section of the device is gettubg warm indicating something is happening. The touch keys are lighting up now but still nothing from the display. I read somewhere you need to charge the device for 8 hours with no screen plugged in since the LCD can drain the battery. I really don't get what's going on I've replaced every single part in this tab s2 and it still doesn't work.

 

[blackhawkhot]

After being plugged in the motherboard section of the device is gettubg warm indicating something is happening. The touch keys are lighting up now but still nothing from the display. I read somewhere you need to charge the device for 8 hours with no screen plugged in since the LCD can drain the battery. I really don't get what's going on I've replaced every single part in this tab s2 and it still doesn't work.

Leave it charge. If the battery is discharge it's possible the charger doesn't have enough current for both.
This is when having known good parts comes in handy.
Somehow you need to isolate the problem(s)...

Note: if the mobo has a conformal coating (plastic) on it you will need to punch through with the test probe to get a reading or connect to it!

 

[blackhawkhot]

The screen is new though, and the old one still worked albeit it was cracked. That one refuses to display too other than the random bright flashes of light.

Its as if the display is not connected to the motherboard properly or there is some fault in the connection given the random screen flashes?

You sure you didn't damage the ribbon cable connector or jack(s)? Inspect.
You have an ohm meter so you can do a pin to pin continuity check on the ribbon cable.

 

[Silent Silent]

You sure you didn't damage the ribbon cable connector or jack(s)? Inspect.
You have an ohm meter so you can do a pin to pin continuity check on the ribbon cable.

Which ribbon cable? I've replaced the LCD flex cable. Can't see any other cables.