2 Seconds to Black - Gateway LE1936

[tpearsall]

Newbie warning!!

Power on the display, shows the screen for about 2 seconds then goes dark. With a flashlight you can see that it is still on. The blue led power button remains on.

1st thing I did was replace the power board capacitors even the looked fine. No change, but it was my 1st experience de-soldering as well as 1st circuit board soldering so just that fact this it wasn't broken worse was a small victory.

Sounds I replace the logic board capacitors?

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

Next I moved on to Step 2 - Shorted Transistors. I tested what I *think* are the transistors.

In the picture the top most one circled was:
1 - 2 = 1.0
1 - 3 = 29.7
2 - 3 = 30.9

Other circled:
1 - 2 = 0.8
1 - 3 = 29.8
2 - 3 = 30.7

Questions:
1) Did I test the right things?
2) Did I miss any?
3) The instructions say anything below 20 Ohms is a bad transistor so are both of mine bad?

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

Not sure what that is circled, but should it rattle? Also, the bottom side if it looks a bit fried. In fact so does the bottom of the capacitor a little higher up on the board.

[budm]

Re: 2 Seconds to Black - Gateway LE1936

What Ohm scale are you using? Ohm, K Ohms, M Ohms?
That part is for rotation sensing when you rotate the screen 90 Degree into portrait position. It has a little ball inside that block/unblock the optical sensor.
Please read this first:
https://www.badcaps.net/forum/showthread.php?t=10419
I would check the transformer high voltage winding resistance.
Worst case will be the lamp assemblies:
http://s807.photobucket.com/albums/y...klight%20lamp/
You may want to make test lamps so you will not spend lots of time try to figure out if it is lamps or power supply-inverter board problem.
Test lamps:
https://www.badcaps.net/forum/showthread.php?t=19987
http://s807.photobucket.com/albums/y...g%20old%20CFL/

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

Sorry for all of the post/pictures, but since this is new to me step by step of what I've done seemed safest. Not sure what to do next?

1) Replace logic board capacitors?
2) Did I miss any transistors to test?
3) Test the MOSFETS? From an internet search I don't see which things on these boards are MOSFETS so direction would be great.
4) I tested the one obvious fuse on the power board and it reported 0 Ohms. Are there other fuses I need to test?
5) Replace rattling thing and scorched capacitor?

Thanks!

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

Thanks for the fast response!

What Ohm scale are you using? Ohm, K Ohms, M Ohms?

200K, not 200 Ohms. When I set to 200 I get Over Range (1 on the left side of screen).

That part is for rotation sensing when you rotate the screen 90 Degree into portrait position. It has a little ball inside that block/unblock the optical sensor.

Darn! I thought I was on to something

Please read this first:
https://www.badcaps.net/forum/showthread.php?t=10419

All over it!

I would check the transformer high voltage winding resistance.

I'll need to research which components they are and how to test them.

Worst case will be the lamp assemblies:
http://s807.photobucket.com/albums/y...klight%20lamp/
You may want to make test lamps so you will not spend lots of time try to figure out if it is lamps or power supply-inverter board problem.
Test lamps:
https://www.badcaps.net/forum/showthread.php?t=19987
http://s807.photobucket.com/albums/y...g%20old%20CFL/

I'll pull them out next. Thanks!

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

You may want to make test lamps so you will not spend lots of time try to figure out if it is lamps or power supply-inverter board problem.
Test lamps:
https://www.badcaps.net/forum/showthread.php?t=19987
http://s807.photobucket.com/albums/y...g%20old%20CFL/

Would this work?

[budm]

Re: 2 Seconds to Black - Gateway LE1936

Try that form factor lamp, it does not work. I tried many form of lamps, the two that worked so far are the one shown in my pictures.
Can I see the good straight front shot of the power supply-inverter and also the bottom side?
By the way, those two components on the logic board are Low Drop Out (LDO) voltage regulator ICs.
Here is the thread on how to test them:
https://www.badcaps.net/forum/showthread.php?t=22231

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

Try that form factor lamp, it does not work. I tried many form of lamps, the two that worked so far are the one shown in my pictures.
Can I see the good straight front shot of the power supply-inverter and also the bottom side?
By the way, those two components on the logic board are Low Drop Out (LDO) voltage regulator ICs.
Here is the thread on how to test them:
https://www.badcaps.net/forum/showthread.php?t=22231

Didn't work for me either . I'll pick up a T5 4w tomorrow.

Attached are what I *think* is the power supply-inverted frond and bottom.

Thanks for all the help!

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

By the way, those two components on the logic board are Low Drop Out (LDO) voltage regulator ICs.
Here is the thread on how to test them:
https://www.badcaps.net/forum/showthread.php?t=22231

Top Voltage regulator from previous picture:
LD117A
L18ATC
{no 3rd line}
Pin 1 - 0
Pin 2 - 1.78
Pin 3 - 5.09

2nd Voltage regulator
A1
AS117L-33
B0512
Pin 1 - 0
Pin 2 - 3.25
Pin 3 - 5.09

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

Didn't work for me either . I'll pick up a T5 4w tomorrow.

Attached are what I *think* is the power supply-inverted frond and bottom.

Thanks for all the help!

I think this is the transformer, but in case I am wrong and it's the power supply inverter...

[budm]

Re: 2 Seconds to Black - Gateway LE1936

In post1 you have the pictures of the power supply/inverter board kind of side way, not straight shot. I need to be able to see the whole (both sides) so I can trace out the connections on the board.
The inverter high voltage transformers are close to where the lamps are plugged into.
The regulators on the main board are OK. You do not have the main board problem, the problem is either the inverter circuits or the lamp problem. The replacement caps you use for the power supply are low ESR type?

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

Not sure if it's relevant ,but correction on symptoms. Power on the display, power light turns blue, shows the screen for about 2 seconds, goes dark 2 seconds, screen back on 2 seconds, screen off, power light turns amber. With a flashlight you can see that it is still on.

Tested CCFLs with the T5 4w bulb and it lights up just like the display, 2 seconds on, 2 off, 2 on then off.

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

The replacement caps you use for the power supply are low ESR type?

Here is the capacitor pack I installed from LCD Alternatives.

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

In post1 you have the pictures of the power supply/inverter board kind of side way, not straight shot. I need to be able to see the whole (both sides) so I can trace out the connections on the board.
The inverter high voltage transformers are close to where the lamps are plugged into.

These should be better. The 3rd image is a close up of a mark near one of the transformers.

Thanks!

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

I would check the transformer high voltage winding resistance.

I desoldered the transformers and they bot tested as follows;

T501
1 to 5: .5ohms
3 to 6: .5ohms
7 to 8: 679ohms
Rest were open

T502
1 to 5: .5ohms
3 to 6: .5ohms
7 to 8: 623ohms
Rest were open

Are one or both bad since the difference is > 3%

Thanks,
Todd

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

I desoldered the transformers and they bot tested as follows;

T501
1 to 5: .5ohms
3 to 6: .5ohms
7 to 8: 679ohms
Rest were open

T502
1 to 5: .5ohms
3 to 6: .5ohms
7 to 8: 623ohms
Rest were open

Are one or both bad since the difference is > 3%.

I'm been searching and can't find this transformer and don't know how to determine an equivalent.

It's a bit blurred, but the tops appear to say:
SP?-068 Rohs
LSE K12AH

Any ideas?

Thanks.

[budm]

Re: 2 Seconds to Black - Gateway LE1936

That is quite big difference between the two transformer. I would do the lamp test next.
Can you take the pictures of the transformer where the P/N is?

[Lumberjack777]

Re: 2 Seconds to Black - Gateway LE1936

I'm been searching and can't find this transformer and don't know how to determine an equivalent.

It's a bit blurred, but the tops appear to say:
SP?-068 Rohs
LSE K12AH

Any ideas?

Thanks.

I'm sure budm will help you figure it out. If it turns out to be an inverter transformer, you are in luck. I believe that part number is SPW-068.
http://www.ebay.com/sch/i.html?_trks...at=0&_from=R40
Except for my caps from Digikey; it seems like 99% of the parts I get nowadays are from China or Hong Kong.
I'm sure budm will help you track down the problem before you need to buy anything. Good luck. ~L-J-7~

[tpearsall]

Re: 2 Seconds to Black - Gateway LE1936

That is quite big difference between the two transformer. I would do the lamp test next.
Can you take the pictures of the transformer where the P/N is?

I had a tough time getting a decent picture.

Shoot! I only tested one lamp port port and it went on for the same 2 seconds and off as the display. After a closer read of the test instructions I should have tried it in each location. Should I solder the transformers back in and use the test lamp in place of each CCFL?

Thanks!