Rca led50b45rq

[x_orange90_x]

Re: Rca led50b45rq

Thank you! Just ordered a couple of them. I'll update you guys when i get them! Thanks again for all of your help!

[x_orange90_x]

Re: Rca led50b45rq

Diodes will be here Thursday. Before i put one in though, i need some reassurance from you experts about the AC connector that i accidentally shorted the other day. I already intend to fix the solder on it, but i would like to know if beforehand if i possibly damaged something else. I'm thinking best case scenario is the bad diode actually protected the rest of the circuitry from the short. What do the experts say?

[vinceroger69]

Re: Rca led50b45rq

when you caused the short did the fuse blow on the power supply?

[x_orange90_x]

Re: Rca led50b45rq

Not really sure as it's not a glass tube type, it's a sealed black square fuse soldered to the board. However, i still has power going through because the standby light still comes on, and the screen still flashes when i try to power up (bad diode).

[vinceroger69]

Re: Rca led50b45rq

that sounds fine then all you can do is wait untill the diode comes fit it and try the tv hopefully its all fine.

[x_orange90_x]

Re: Rca led50b45rq

The Diodes came early.. However, after installing a new one the EXACT same problem persists. I noticed there are two more diodes across the broad from D4 labeled D17A and D17B. Could one or both of these be bad?i

[budm]

Re: Rca led50b45rq

So the PS-ON is present and you are still getting only around 160VDC between the two legs of the main filter cap?
The other two diodes are the low Voltage diode in the secondary side of the power supply, they are not the same as that PFC diode.
BTW, verify that the new diode did not short out again and properly installed.

[x_orange90_x]

Re: Rca led50b45rq

I will check voltages again tonight at PS-ON and at EC1 and EC1A. Is there anything else you want me to check besides these and the new diode? I only get about 20 minutes in a day to do this, so I'd like to get you as much information as you need.

Do you need me to check EC1- to PIN 12 of L6599 again?

Edit - just stumbled across this thread http://www.diyforums.net/rca-led50b4...ch-129823.html

The OP describes exactly what is happening with my set. Turned out to be bad backlights. I'm going to try what he did in post 15 and see if i get the same results as he did.

[budm]

Re: Rca led50b45rq

You need to get the PFC Boosted Voltage working first before going further.

[x_orange90_x]

Re: Rca led50b45rq

Ok. I'll check the diode and voltage at EC1 and EC1A tonight and let you know what i find out.

[x_orange90_x]

Re: Rca led50b45rq

Just finished checking. I've got 171.8v on EC1 and 171.4v on EC1A. D4 diode reads 000 one direction and 461 in the other. I did the flashlight test and CAN see the menu on screen, so I'm pretty certain now its one or more bad LED backlights.

[budm]

Re: Rca led50b45rq

So the PFC is not wroking, without that boosted Voltage for the LED driver power supply, that section is not going to work, bad LED is another problem if it is bad, so you may have more than one problem.
You have PS-ON but no boosted Voltage at this point which need to check furthEr to see if the PFC IC is getting the VCC to run or not.

[x_orange90_x]

Re: Rca led50b45rq

What do i need to check now?

[x_orange90_x]

Re: Rca led50b45rq

As poorly written as this is, it's relevant enough that i now understand what your trying to say. I'm only getting 171v at those caps when they SHOULD be much greater than that (the boosted voltage).. In turn not supplying enough voltage to the main board. This is why i can power on and see the menu with a flashlight ONLY when the LED connector is unplugged (because there's enough voltage to power the display without the LEDs trying to rob that power).

He said there's only two things between the rectifier and filter caps: The PFC IC and resistors. So the resistor/s may be bad, or the IC, correct? If so, which ones and how do i check them?

[vinceroger69]

Re: Rca led50b45rq

you need to find the pfc ic and carefully check the voltages whilst the tv is in the on condition (dont let your probes slip as this will cause damage if ic shorted)
find the pfc ic then the data sheet for it and see what the vcc voltage is.

[x_orange90_x]

Re: Rca led50b45rq

Found the datasheet for L6599. In the attached picture, i need to check DC voltage been PIN 10 and 12, right? What would be the correct voltage if the IC is in good shape?

[vinceroger69]

Re: Rca led50b45rq

Found the datasheet for L6599. In the attached picture, i need to check DC voltage been PIN 10 and 12, right? What would be the correct voltage if the IC is in good shape?

Im still learning but it looks like its operating voltage is between 8v and 16v so take all voltages of the ic as im sure budm will advise you further then.

[dick_barton]

Re: Rca led50b45rq

Found the datasheet for L6599. In the attached picture, i need to check DC voltage been PIN 10 and 12, right? What would be the correct voltage if the IC is in good shape?

See post #42

[x_orange90_x]

Re: Rca led50b45rq

Do i check with my black probe on PIN 10, or the EC1- leg?

[dick_barton]

Re: Rca led50b45rq

The EC1 negative leg would probably be easier and less risk of shorting pins on the IC accidentally.