Sharp Aquos 70" LED LC-70LE632U does not power on

[Teletubbie]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

I cannot seem to find where to source this part online. Would it be available in a Radio Shack store?

Should I test more parts on the board while I source this diode?

[budm]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

SB2100:

[Teletubbie]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

Desoldered one end of D7951 and it still measures 0.0 on the multimeter diode test. The following name is marked on the diode SB2100 (first row) and 050 (second row). Not sure of the letter 1 or I in "SB2100".

[budm]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

I uploaded the pix from SJ on post 22.

[Teletubbie]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

While I desolder the diode and test it, here is a high resolution image of the back side of the power board with the diode D7951 marked in red in the lower left corner.

[budm]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

Does it matter which one end of the diode I desolder to test it?

No.

[Teletubbie]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

Does it matter which one end of the diode I desolder to test it?

[budm]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

Diode D7951 is the half-wave rectifier, C7951 is the filter cap, this feed the 5V regulator IC7590 for the BU5V (STBY 5V) PD pin 15.
So did you lift one leg of the diode and retest it?

Sharp RUNTKA857WJQZ (DPS-222BP, 2950284203) Power Supply Unit
http://www.shopjimmy.com/sharp-runtk...pply-unit.htm#
Pictures provided by shopjimmy.

[Teletubbie]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

You need to check the main PFC capacitors with the power plugged in. Black lead to negative on capacitor and positive with red lead. You should have about 170 volts DC across each of those capacitors

Checked the voltages with the power plugged in and it measured 170V DC for all three main capacitors.

[freakaftr8]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

After I turn the board over, how do I test the transformer? I would like to first check the transformer voltages and make sure it is not shorted before I desolder the diode. Thanks.

I seriously doubt anything's wrong with the transformer. The reason i mentioned desoldering and pulling up one side of the diode is to properly test it out of circuit. The transformer will give a Non conclusive reading With the diode in circuit due to the fact that the transformer is completing a circuit on both sides of the diode

[freakaftr8]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

You need to check the main PFC capacitors with the power plugged in. Black lead to negative on capacitor and positive with red lead. You should have about 170 volts DC across each of those capacitors

[Teletubbie]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

the device reference number from the board is d7951. Anyways, once you desolder one side, you will likely see what the actual component number is. Further, if you look on the circuit side of the board, you should be able to potentially see what it is connected to. From the picture, it is near a transformer so it is likely taking an output from one of the legs of the T and rectifying it. Potentially, once you see the output of the transformer and accessible "test access points", you should be able to check for voltages coming out of the transformer in some form just to further confirm your suspicions about the diode... maybe.... as opposed to possibly the transformer being shorted which might have thrown of the "in-circuit" diode test.

After I turn the board over, how do I test the transformer? I would like to first check the transformer voltages and make sure it is not shorted before I desolder the diode. Thanks.

[Teletubbie]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

On the PD connector do you get any output dc voltages at all? Looking for a pin with 5v or 3.3v. also what is the.voltage you measure across capacitors C7800 a thru c?

Connected the TV power plug and checked the PD connector. No voltage present on any test points.

Disconnected the power and checked the C7800s. All the capacitors A thru C measured 39.3 V DC.

[freakaftr8]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

Also agreed on the diode. It could be in parallel with the transformer giving an off reading. The only way to test that diode is desolder one side and read it's measurement.

[freakaftr8]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

On the PD connector do you get any output dc voltages at all? Looking for a pin with 5v or 3.3v. also what is the.voltage you measure across capacitors C7800 a thru c?

[budwich]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

the device reference number from the board is d7951. Anyways, once you desolder one side, you will likely see what the actual component number is. Further, if you look on the circuit side of the board, you should be able to potentially see what it is connected to. From the picture, it is near a transformer so it is likely taking an output from one of the legs of the T and rectifying it. Potentially, once you see the output of the transformer and accessible "test access points", you should be able to check for voltages coming out of the transformer in some form just to further confirm your suspicions about the diode... maybe.... as opposed to possibly the transformer being shorted which might have thrown of the "in-circuit" diode test.

[Teletubbie]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

sorry but I can't seem to see what you reference the "red marked diode".... do you have a component number. If the diode (s) are all similar in response and one is not, its a good chance that you may have found your issue. However, "in-circuit" testing isn't always "concise". Potentially, you might have to "lift" one lead of component from the board to isolate it a bit and go from there.

I do not have a parts list for this board. I see there are two numbers printed on that red-marked diode. "10" on the first row and "22" on the second row. Do you think I should desolder this diode to get an accurate reading?

[budwich]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

as for the ferrite beads... they are basically jumpers, so unless they have significant issues (broken / burnt / cracked solder joint), I doubt they are the problem.

[budwich]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

sorry but I can't seem to see what you reference the "red marked diode".... do you have a component number. If the diode (s) are all similar in response and one is not, its a good chance that you may have found your issue. However, "in-circuit" testing isn't always "concise". Potentially, you might have to "lift" one lead of component from the board to isolate it a bit and go from there.

[Teletubbie]

Re: Sharp Aquos 70" LED LC-70LE632U does not power on

Power Board Testing

I tested the voltage at the input point and it checked out okay at 123V. The fuse also tested okay.

Did a visual inspection of the capacitors and there is no obvious bulging or leaks.

I set the multimeter to Diode mode and all the diodes on the board tested around .45 V except the one marked in red in the attachment which showed 0.

I am assuming the components marked with FB on the board are ferrite bead and they appear like a diodes with a solid black color without any color band. Do I need to test them?