Sceptre X505BV-FMDR

[BadGoo]

Re: Sceptre X505BV-FMDR

Alright. I've discovered something odd in my opinion. I was testing the connections here from the LED driver board to where it connects at the bottom of the TV. I'll try to explain it clearly.

When I disconnect FIG B. and test continuity of each wire, they all have continuity with ground and/or each other.

When I disconnect FIG. A (from the bottom of the TV), there is no continuity between the wires except similar (red, black).

FIG B. pins all test fine (no continuity except similar)
FIG A. pins all have continuity.

Is this normal?

In the 3rd photo, I'm getting 6.6v from that connector which leads into the back of the chassis.

[BadGoo]

Re: Sceptre X505BV-FMDR

bump.

[BadGoo]

Re: Sceptre X505BV-FMDR

Well, I replaced the PSU board with no result. At the connection that goes to the LED back-light, I'm only getting 7v.

[CapLeaker]

Re: Sceptre X505BV-FMDR

what do you get if you unplug that cable? Does the voltage ramp up and then fall down or what? Also measure the BLon pin against chassis GND.

[BadGoo]

Re: Sceptre X505BV-FMDR

what do you get if you unplug that cable? Does the voltage ramp up and then fall down or what? Also measure the BLon pin against chassis GND.

If the Back-light cable is unplugged, I get ramp up to about 300v then falls down to 7v in about 10 seconds and the same if it is plugged in.

As far as the BLon pin, I get nothing if the harness isn't connected to the main board. If it is, it's 3v at the PS and 4.5v at the main board.

[CapLeaker]

Re: Sceptre X505BV-FMDR

So you got a bad backlight led, as there is an open. Nothing wrong with the PSU.

[BadGoo]

Re: Sceptre X505BV-FMDR

Alright. Is it worth trying to replace the LED strips? At first look, I can't seem to find any LED strips online with the part number that's on them. Each one has 7 LEDs and a total of 10 strips.

2 LEDs are bad. The rest light up when tested. I highlighted them in the photo.

Thanks for the help!

[BadGoo]

Re: Sceptre X505BV-FMDR

I've searched and searched for the LEDs and have come up empty. Does anyone have any other resources or a connection to get these? If I could figure out what LED is being used, I'd just rework it onto the strip.

[Agent24]

Re: Sceptre X505BV-FMDR

Perhaps if you can figure out the package type and then search for LEDs in that package type at Digikey or eBay etc.

[BadGoo]

Re: Sceptre X505BV-FMDR

I believe the package is PLCC-2. I grabbed a few to test out and they are close but not nearly as bright at the same voltage. Does anyone know what a typical LED rating is for LED Back lit TVs?

[Agent24]

Re: Sceptre X505BV-FMDR

I'd not be surprised if they overdrive them somehow. It would explain why the die all the time.

[CapLeaker]

Re: Sceptre X505BV-FMDR

Take an old working led and fire it up with a variable power supply. Measure voltage and current with a lab PSU. It should get you in the ball park anyway. Since the new ones are darker than the old ones, that means the voltage rating on the new ones are higher than the old.

[Peter Chiu]

Re: Sceptre X505BV-FMDR

Highly recommend for every Tech : LED SOLDER PASTE (Lead-free SMT Low temperature solder paste) Sn42 bi58 138°C. Ebay has it.

[budm]

Re: Sceptre X505BV-FMDR

Most LED backlights for TV are driven over 100 mA,

[Peter Chiu]

Re: Sceptre X505BV-FMDR

I am so cheap ! I used Rose's metal to desolder the IC (Melting point is 95 °C),after that collect all the desolder beads then use for low-temperature soldering (like led, now the melting point may be 120°C-140°C). The secret is Bismuth.

Rose's metal. It is a eutectic alloy of ~ 32 % lead, ~ 50 % bismuth, ~ 18 % tin by weight. Melting point is 95 °C Applications: low-melting solder

[Alastair E]

Re: Sceptre X505BV-FMDR

I am so cheap ! I used Rose's metal to desolder the IC (Melting point is 95 °C),after that collect all the desolder beads then use for low-temperature soldering (like led, now the melting point may be 120c-140c). The secret is Bismuth.

Rose's metal. It is a eutectic alloy of ~ 32 % lead, ~ 50 % bismuth, ~ 18 % tin by weight. Melting point is 95 °C Applications: low-melting solder

Nothing wrong with Cheap!--I Like Cheap.....

What you basically made is 'Chipquick' that low-temp de-soldering aid--thats hideously expensive for what it is!

[BadGoo]

Re: Sceptre X505BV-FMDR

Take an old working led and fire it up with a variable power supply. Measure voltage and current with a lab PSU. It should get you in the ball park anyway. Since the new ones are darker than the old ones, that means the voltage rating on the new ones are higher than the old.

I tested them out of the unit. Even @ 3.3v the original LED is much brighter than the ones I bought @ 3.3v. What directly affects this? mcd rating etc.? I don't mind buying LEDs to test, I'd just rather not have 100s of LEDs.

These are the two I tried first.
ASMT-UWB1-NX3B2

ASMT-UWB1-NX302

[Peter Chiu]

Re: Sceptre X505BV-FMDR

I did fix two of the LED screens, I am so cheap ...All I do just shorted the LED (by copper thin wire). It work Ok. You won't notice if u don't pay attention to it. .It's a 32 inch cheap TV anyway. I may not do it to the 50 inch TV.


P.S:
If not bright enough just put series or parallel two leds together.
If too bright put some resisters will work.

[Agent24]

Re: Sceptre X505BV-FMDR

I did fix two of the LED screens, I am so cheap ...All I do just shorted the LED (by copper thin wire). It work Ok. You won't notice if u don't pay attention to it.

The problem with that is the voltage across the remaining LEDs will now be slightly higher, so they will die quicker.

[Peter Chiu]

Re: Sceptre X505BV-FMDR

Willyam1: {The power supply is AY160D-4HF01. an ic BD9211F that drive the leds section. pin 1 vcc=11.8v pin 2 stby on /off 4.65v ther no pulses in the output pin 18+17 could be the bad ic?}

I think IC is in protection mode! Pin 13(Error Indication signal Output) is FAIL...... Normal : L Error : open


CapLeaker:{So you got a bad backlight led, as there is an open. Nothing wrong with the PSU.}

Wow !!!!!You're GOOD !!!!!!


I am more interested to know, how to troubleshooting next LED TV

There are ways to test the LED light.

1. use dumping-load to test the power supply see if output are DC 190v - 400v

2. Use the out side power supply give LED the right testing voltage and constant current( may blow all the LEDs).

3.unprotected the IC BD9211, Maybe Pin 5 (FB) to ground. Force the LED screen to light up. Anybody! Please, Let me know?