Rca led50b45rq

[x_orange90_x]

Re: Rca led50b45rq

Both EC1 and EC1A are 172.4v when power is ON.

[dick_barton]

Re: Rca led50b45rq

If the voltage at the capacitors was 172V & PS_On was ON (3.5v) then it looks as though the PFC circuit (L6599) is not running.

Taking great care, with the black meter lead on the -ve leg of EC1 and the red meter lead on pin 12 of the L6599 and the set out of standby what dc voltage do you have on that pin. It needs to be a minimum of 10.7V

[budm]

Re: Rca led50b45rq

Check PFC Diode D4 off the board to see if it show resistance reading on both directions, make to report if the reading is in OHM, K OHM, or M OHM

[x_orange90_x]

Re: Rca led50b45rq

If the voltage at the capacitors was 172V & PS_On was ON (3.5v) then it looks as though the PFC circuit (L6599) is not running.

Taking great care, with the black meter lead on the -ve leg of EC1 and the red meter lead on pin 12 of the L6599 and the set out of standby what dc voltage do you have on that pin. It needs to be a minimum of 10.7V

What order are the pins? Which one would be 12?

I'm guessing you say to take great care because of the difficulty of probing on opposite sides of the board?

[dick_barton]

Re: Rca led50b45rq

Check if the IC has a dimple close to pin 1. Cannot make it out from the photo above and refer to attached pinout.

With the mainboard disconnected and any jumpers in place, turn the power supply board over and rest carefully with the power supply resting on an insulated surface so that nothing can short out.

You need to take care because of the voltages and also not to short any pins out on the L6599.

If your meter probe is to thick to place carefully on pin 12 then tape a needle securely on the probe tip and you can then use the needle point to test pin12.

[x_orange90_x]

Re: Rca led50b45rq

With the mainboard disconnected and any jumpers in place, turn the power supply board over and rest carefully with the power supply resting on an insulated surface so that nothing can short out.

Ok, so at this point the only connector that should be plugged in is the AC power, correct? I don't have to turn the set on for this check?

[dick_barton]

Re: Rca led50b45rq

I can see from your replies that you are not familiar with testing.

However did you check the diode D4 as suggested by Budm post #43.
Unsolder one end of the diode and lift it clear of the circuit board. With your meter set to diode mode check across the diode. This test is done with the set disconnected from the mains.

[x_orange90_x]

Re: Rca led50b45rq

You are correct! I have some experience, but very limited if that makes sense. I'm just trying to be certain that i don't have connectors plugged in when they shouldn't be. When you say "disconnected from the mains, you are saying NOT to have power to the board, am i right?

I haven't checked the D4 diode or Pin 12 yet as i am currently not at home. I'm just trying to be certain that I'll know exactly what to do when i am back in front of the set.

[heavymachines]

Re: Rca led50b45rq

Yes no power....

[x_orange90_x]

Re: Rca led50b45rq

Ok i got those tests done. EC1- to PIN 12 of L6599 was 0.42v (checking with 20v setting of meter), and D4 reported 000 both directions.

[budm]

Re: Rca led50b45rq

Ok i got those tests done. EC1- to PIN 12 of L6599 was 0.42v (checking with 20v setting of meter), and D4 reported 000 both directions.

If that DATA is correct, that diode is bad and that is why you are not getting the PFC Boosted Voltage.

[x_orange90_x]

Re: Rca led50b45rq

So this diode need to be replaced then.. What type of diode am i going to be looking for as far as replacement? I have never replaced one before but i have plenty of experience with capacitors and soldering.

[budm]

Re: Rca led50b45rq

P/N as printed on the diode?

[dick_barton]

Re: Rca led50b45rq

As Budm has said if your diode measured 000 with your meter set to ohms or diode mode then it needs to be replaced.

[x_orange90_x]

Re: Rca led50b45rq

I checked it in Diode Mode. I'll look later for the P/N on it. Thank you guys for all of your help! You're very smart people ��

[x_orange90_x]

Re: Rca led50b45rq

Attached is a photo of the diode.

I have a huge bag of caps and diodes, but none with this same number. I read something about being able to use higher rated diodes in place, but I'm not sure if that's true. I did find one that is the same size, but with different numbers on it. It is "IN5408 222" Would it possibly work?

[dick_barton]

Re: Rca led50b45rq

The only diode I could come up with to match 460P was NUR460P. It looks identical though to the MUR460. The IN5408 is not a suitable replacement.

[budm]

Re: Rca led50b45rq

Or MUR460.

[x_orange90_x]

Re: Rca led50b45rq

Do you guys know a good place to buy one from? Everywhere I'm finding wants me to order 1000 of them minimum lol

[budm]

Re: Rca led50b45rq

http://www.digikey.com/products/en?k...s=MUR460GOS-ND