Sceptre X22WG-1080p monitor not staying backlit, Please Help!

[trex66]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

OK, ran the monitor through every combination of my spare CCFL and the other four leads. This time I couldn't detect any difference between any 2 and off cycles. I tried to reproduce what happened yesterday, but I couldn't. I would like to write off the CCFL's but I know the test CCFL I have is not the same size as the ones in the monitor and it came from a used screen.

I re-tested the surface mount components I couldn't get a reading from and I got a 55.76 KΩ for the resistor but still nothing from those two caps...

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

Also didn't know what to do with the J- Jack connector.

J is jumper. That is why it says 0 for 0 ohms.

[trex66]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

I couldn't get a reading on two caps and a resistor, I've tested over and over, switched leads and same results. I can't believe three component went bad at once? Also didn't know what to do with the J- Jack connector.

Note this pic I drew on is the old one with the pin not attached.

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

Okay, resolder pin 16.

With power off and lcd unplugged, test each one of the components in the yellow box.

R components should be tested with ohms measurement. The multimeter should give you a reading close to the markings.

C components should be tested with capacitance. If you don't have a capacitance function, use ohms. Any reading under 30 ohms suggests the capacitor might be shorted.

D components should be tested with the diode test function. Put your red probe on one side and black on the other. Record measurment. Reverse probes and repeat.

After these measurements, you can try alexanna's suggestions.

[trex66]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

That's odd, I also missed that post, I didn't re-test but I can when I fix the 16 pin. Here are some more pics. I didn't notice it until I was really looking close. Yes, 2 sec to black with each connector except for the third one, which gave me one sec at full, 1second at half brightness and then off. Also the CCFL I used was from a used 15" LCD, but measures 12.5"

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

Someone how I missed alexanna's post #31. Did you retest as suggested?

And just to confirm, in post #29, you got 2 seconds to black when switching in the 12.5 inch ccfl into each connector. That is, three Sceptre ccfl tubes + one 12.5 inch tube.

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

sorry, 59.06 K Ohms

None of those readings suggest the BIT 3717 is shorted. BIT 3717 could still be bad in other ways though. If you rub the chip, does it feel bubbled up?

Can we a slightly zoomed out picture (like the one in post #32) with resolution as close to 2000x2000?

Hold off on resoldering the pin back in.

[trex66]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

sorry, 59.06 K Ohms

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

that was tough, those pins are so small- got a new reading

10-16 = 59.06

Does this mean something else is causing the short and the IC is good? Should I re-solder the pin?

Is that 59 ohms or 59K (as in 59,000) ohms? The other readings in post #39 have K ohms.

[trex66]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

that was tough, those pins are so small- got a new reading

10-16 = 59.06

Does this mean something else is causing the short and the IC is good? Should I re-solder the pin?

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

10-16 0.2 Ω

There are a few possibilities.

1) pin 10-16 is shorted by design (internally to the IC)
2) pin 10-16 is shorted by damage to chip
3) pin 10-16 reads shorted by other components on the board

If you are good at soldering, try to lift pin 16 so that it is off the board. Then retest, pin 10-16. If it is still reading 0.2 ohms, we are left with #1 or #2.

Looking at the datasheet, I'm not 100% sure, but I think pin 10-16 should not be shorted. That is, I believe the chip is damaged.

edit: pin 10 is VDD (power supply pin of the device), and pin 16 is MODSEL.

[trex66]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

retiredcaps you're my seeing eye dog in this electronic world.

it will be easier to list the readings I did get, most of the connections were 'OL'

2-7 55.84 KΩ
3-7 54.28 KΩ
4-7 56.40 KΩ
5-7 46.95 KΩ
6-7 53.09 KΩ
7-14 54.71 KΩ
10-11 57.72 KΩ
10-12 58.58 KΩ
10-13 57.74 KΩ
10-14 57.41 KΩ
10-15 58.56 KΩ
10-16 0.2 Ω

I hope this can help shed some light on what is wrong here.

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

Please use the exact orientation and pinout as the datasheet otherwise there will be mass confusion.

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

I don't have a clue where to start to test this IC...

Let's try this. It is brute force, but it gives all the readings possible. If you have a manual multimeter, set it to 200 ohms. If the multimeter reads "1" on the left hand side it is out of range. Just report the pin configurations that have resistance less than 200 ohms.

With power off and lcd unplugged, measure the resistance between (I think you will see the pattern)

a) pin 1-2, 1-3, 1-4, etc, etc, 1-15, 1-16
b) pin 2-3, 2-4, 2-5, etc, etc, 2-15, 2-16
c) pin 3-4, etc, pin 3-16
..
..
..
y) pin 14-15, 14-16
z) pin 15-16

The members here can then help interpret the results.

[trex66]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

Nice, I searched for hours and came up with nothing. I don't know where you found it, but thanks.

I don't have a clue where to start to test this IC... I can't read the block diagram, no idea what any of those initials stand for, or where they are on the board. I feel like the kid who jumped in the pool then realized he couldn't swim.

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

I found the exact one.

https://cdn.badcaps-static.com/pdfs/...3c7c387216.pdf

You want the exact one because there could be changes between chipsets over time.

[trex66]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

Wow, talk about a hard to find datasheet... well never found it but there is a similar IC BIT3193 that I found. here is the link to the PDF. Again, thanks for all the help.

http://pdf1.alldatasheet.com/datashe...C/BIT3193.html

[retiredcaps]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

I don't have a ESR meter, the DMM I have reads capacitance but I have to pull the caps off the board to get an accurate reading.

Hold off desoldering and measuring uF for now.

BIT 3713

Also didn't see this before, there is a small bubble on it, hard to see, but looks like a little damage.

Find the BIT 3713 datasheet and see if any of the pins are shorted. Post the link for the datasheet.

The datasheet usually has a functional block diagram that will help you determine which pins should not be shorted.

I agree that looks bubbled and that chip could be damaged.

[trex66]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

I didn't know if the CCFL's were full length or front to back behind the screen. I don't have a ESR meter, the DMM I have reads capacitance but I have to pull the caps off the board to get an accurate reading. the IC is very hard to see, from what I can make out is reads:
BIT 3713
F1FT7 CO652

Also didn't see this before, there is a small bubble on it, hard to see, but looks like a little damage.

[alexanna]

Re: Sceptre X22WG-1080p monitor not staying backlit, Please Help!

How I tested the four CCFL's was with a 12.5" CCFL lamp from another monitor. I just unplugged one lamp and plugged the spare into it. I did this with all four lamps. And I turned it on and off a few times ti verify the results. It's possible the lamp I used was too pulling too much power?

I have a few monitors around, but these only have one or two lamps, not a four lamp. Can I still use one to test the board?

I am guessing when you say a 12.5”ccfl your talking about one from a 15” monitor.
You definitely noticed something different on one side of the inverter.
I am going to suggest you try one more thing. Position the panel so you’re able change the position of where the ccfls plug into the board [top ccfls plugged into where the bottom ones were]continue to use your test bulb repeat you testing,see if one second on and dim, stays with the same ccfls connector.
Al.