Rca 42la45rq

[ser4320]

Re: Rca 42la45rq

So the backlights stay on but the screen just has slight glow?
We need the pictures that show all the boards and how all the boards are connected together. The power switch on the TV works, right?
We need to see if the T-CON is getting the 5V/12V from the main board or not.
History of this TV on how it went out? Surge/ Lighting?
You may have EEPROM problem:
http://www.shopjimmy.com/catalogsear...q=Rca+42la45rq

wwwshopjimmy.com will fix you up for 15$

[toddw65]

Re: Rca 42la45rq

WP7W is most likely to be the P-CH MOSFET, you can see that the 12V is fed to the Source (right pin) but nothing is at the Drain (top pin) because the GATE (left pin) is at 11.61V, it need to be at least 2~3V < than the Source pin Voltage.
To have the Gate Voltage goes lower the H1A NPN needs to be bias ON so the Collector (top pin) will go low, right now you are getting 0V between Base (left pin) and the Emitter (right pin) that means the controller is not sending the signal to turn on the H1A.
You can force on the MOSFET by using 2~3K resistor between GATE and GND.

I have forgotten sooo much over the years.

On the bright side, I ran a 2.4K resistor between ground and gate which turned on the MOSFET giving me 12v at the drain, 12V to the TCON, and yes, a "No Input Signal" on the screen.

Where does that point me now?

[budm]

Re: Rca 42la45rq

Good at least the other function of the main board and the T-CON are OK, rights? You should check the all the functions of the TV.
So as I indicated that the processor is not sending the ON command to turn on that NPN transistor.
We can modify the board by using the BL_ON signal to turn on the T-CON.
You can also leave the resistor in place since when you turn the TV off the 12V will alo be turned off too.

[toddw65]

Re: Rca 42la45rq

Good at least the other function of the main board and the T-CON are OK, rights? You should check the all the functions of the TV.
So as I indicated that the processor is not sending the ON command to turn on that NPN transistor.
We can modify the board by using the BL_ON signal to turn on the T-CON.
You can also leave the resistor in place since when you turn the TV off the 12V will alo be turned off too.

Well I left the resistor in place and the menu looks great. Unfortunately, only some of the control buttons work and the one for switching inputs isn't one of them. Also, no response to the remote.

[budm]

Re: Rca 42la45rq

So the main board still has lots of other problem, you can try new board or new EEPROM I guess.

[toddw65]

Re: Rca 42la45rq

Unfortunately, I got the following response from ShopJimmy:

Unfortunately you've got a version we don't have ourselves nor will any of our EEPROM ICs do the trick. The 1B1l1979 is the part number on yours, found on the barcode sticker on the backside. LC420WUE-SCV1 is also needed to determine the version of that part number you'd need. Basically both of those numbers must match for you to find a proper replacement. As mentioned we don't have this for you ourselves. Sorry Todd! If you need anything else do let us know.