RCA 46LA45RQ 2 seconds then lights out, intermittent

[rockola1454]

Hi all,

I have an RCA 46LA45RQ which I am attempting to bring back to life. Some of the time it comes on with no issue and works fine for hours. The other half of the time, the backlight goes out after 2 seconds (a flashlight can show the image). When it comes on in this "mood," turning it off/on repeatedly has no effect.

I first tried a factory reset, to no avail.

Next, I suspected the Megmeet psu. I tried running a heatgun over the psu for a bit to gently warm things up, but the lights still go out after 2 seconds. Not satisfied, I tested all electrolytics on the psu, finding none bad or significantly out of range.

I then made the assumption the Samsung SSI460_12A01 inverter was faulty, and obtained a new one. Unfortunately, still no difference. On both the old and new inverter board, I see 24 volts steady regardless of whether the light stays on or not.

I don't know if this means anything, but through holes in the back of the panel's metal frame I can see the light start out and in a fraction of a second get 20% brighter when (and only when) the lights decide to stay on. Watching from the back I can usually predict the lights will go out if the lights don't start then very quickly get a little brighter.

Any advice appreciated!

-Chris

[rockola1454]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

I'm wondering if I should get a replacement power supply, or if I should look in the direction of the cfl bulbs being bad. Any thoughts?

[budm]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

https://www.badcaps.net/forum/showthread.php?t=39740

[rockola1454]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

Ah, I'm sorry about that, I totally missed adding pictures. Here are some. Since I have a spare of the inverter board, I just laid it on the panel in the first picture for reference.

If close-ups of anything in particular would be helpful please let me know, I'm happy to take as many as needed.

And thanks for any help you can provide!

[newtothis]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

So...

Swapped Invertor no change, 24v present at invertor regardless of if the backlight is on off? Correct?

Leaves one thing - Failing CCFL

[rockola1454]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

Thanks! That makes sense. I took the panel assembly apart and have the bulbs exposed. They all stay lit at the moment, but one bulb had a "barbers-pole" look to it for several seconds. I'll keep trying it today to confirm if that is the (only) problem bulb.

If I've done my measurement right, I'll be looking for a 4.0 x 1025mm bulb. Any recommended places to buy them? I noticed www.ccflwarehouse.com...
Also reading through the threads, seems like I need to wipe down the panel with a dust cloth prior to reassmbly, someone recommended Guardsman.

[rockola1454]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

I believe the problem is solved!

Was powering the set on/off on its back without the LCD panel for a good while trying to determine which bulb is bad, but without any failures. I decided to inspect the connections of each bulb more closely and found 2 ground sockets "unlocked" themselves. The cathodes of the bulbs were pretty black in those sockets; some light sandpaper brought back the shiny color. Locked them back in by pressing down on the sockets with my thumb and haven't had any problems so far. Awaiting an anti-static wipe to put the panel back.

Thanks again for pointing me in the right direction, guys! Hope this post helps someone else with the same issue. Beers on me!

-Chris

[budm]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

Good job!. I can see some of the lamps has blackened ends so they will more likely to fail later, if it has backlights level control, I would set it to about 80% or so that may extend the life of the lamps.

[Watts]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

Hi all
I have a late model rca 46la45rq with the samgsung LCD assembly and having
almost the same problem. I walked out of the room and when I came back the lcd was dark but sound was still working. The flashlight test showed the image was was there so I assumed the inverter was bad. Up until that time the lcd was bright and clear but since then the 2 second on then off is it.

The power supply board seems to be working fine with all votages dead on.
Resistance test showed very similar accross all 3 tranformers and surrounding circuits. I have a small handheld video game that I use as a A/V source and for the 2 seconds the image is bright and clear.

pics
https://s28.postimg.org/9byvklr4d/DSC00195.jpg

main board
https://s24.postimg.org/sxjfhp79h/DSC00185.jpg

Power board
https://s27.postimg.org/l7afyzer7/DSC00188.jpg

Inverter board
https://s29.postimg.org/ltno9ea87/DSC00204.jpg

First I would like to know if anyone has a service manual for this set or
provide me information for trouble shooting the senser circuit. I will open up the backlight cage tomorrow and check the connections as mentioned by the previous poster but don't expect to find anything there.

Here is a pic to the one possible problem area that I found. If I measure the
voltage on the pin on the inverter board at power up the voltage is 5.0 but
as soon as the tubs fire up the voltage drops to 3.24. I don't know if these
voltages are normal or not but for now it's the only thing I have found.

https://s29.postimg.org/rc0at19on/notes.png

Thanks in advance
Watts

[Watts]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

Forgot to mention the inverter number is SSI460_12F01 SSI460-12F01 LJ97-03319A

[Watts]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

Another picture showing the other end of the 3-pins shown in the last pic

SSI460_12F01 SSI460-12F01 LJ97-03319A

[Watts]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

my bad, here is the link. https://s29.postimg.org/ela7eg9ef/note_2.png

[CapLeaker]

Re: RCA 46LA45RQ 2 seconds then lights out, intermittent

measure the secondary HV output winding with your meter set to ohms of each transformer on the inverter board. Compare them to each other. If there is more than a 3% difference in reading, the transformer is bad.
Usually there are bad capacitors (specifically those under the heat sink on the PSU) and those caps on the inverter board, bad HV transformer on inverter board and last RCA has bad connections at the lamps and or wiring between CCFLs and inverter board.