Led24a45rq

[SolomonMan]

All,
I have a RCA LED24A45RQ...picked it up last summer from a fellow that said he thought the main "tube" was going bad as he would occasionally see wavy lines in the small TV.

He bought a new bigger TV.

I noticed that he was next to a large Communication tower and brought the TV home. So I assumed it as interference he saw and just wanted a new TV.

I powered it up and it looked and acted fine...used it probably once or twice a month as computer screen for my young kids.

Anyways turned it on the other day and I am getting no picture.

The unit power light (red) displays as it should when in off mode and goes away when you press the on button.

Upon putting the TV in a dark room and using my Phone light against the screen...I see a menu screen when the menu button is pressed and a No Signal (looking for) box other times.

I have tried hooking it to my BluRay by HDMI and selecting the proper HDMI and all the others (using the light setup mentioned) and I get no picture/sound....

Any Ideas?

Is it the main board?

Not had a chance to take apart yet but initially thought the inverter board until I did not get my BluRay to work on it.

Thanks in advance,
Chris

[R_J]

Re: Led24a45rq

You have an issue with either the backlight voltage driver or most likely a bad led string in the panel. Since you can see the menu by shining a light on the panel the video processing part of the main board is likely ok, BUT I believe this model has the backlight driver as part of the main board and not the power supply. Again post some pictures.
On some of the main boards there is a fuse (F2) next to CN9 plug, check that it's not open.

You can check the voltage going to the panel led's with a volt meter, You need to connect the meter, then turn the tv on and see wht the voltage does. If it goes high then drops down this usually indicates an open led string (one or more bad leds)

[SolomonMan]

Re: Led24a45rq

R_J,
To confirm my understanding on your last post...The LED Backlights are being driven from the main board instead of the power supply?

Is the voltage probably somewhere around 24 volts like I have seen in a few other TVs?

If its the LED light string is that something that can be repaired easily/cheaply?

Never replaced A LED string before...

I probably will not get a chance to look at it till Saturday night.

Thanks again for the help,
Chris

[nomoresonys]

Re: Led24a45rq

Take the back off, might be something obvious.

[SolomonMan]

Re: Led24a45rq

All,
Did some more diagnosing on the TV...basically if you turn it on the TV flashes a good screen for a split second before turning off the back lights...never saw that till I played with it some more today.

So I finally took the back of the TV off and did a quick scan across the easier visible boards to see if any capacitors or hot areas appeared...I did not see any quickly...but the ribbon cabling was fairly tight so I went to take the ribbon cable for the back lights off.

After removing the strong cloth like tape it appears the connection was green/black burnt?/corroded.

I slowly backed the ribbon cable out. I sprayed some contact cleaner into the screen side of the connector and similar to the ribbon cable but the ribbon cable was corroded/possibly burnt. I used a soft toothbrush to clean both sides the screen side cleaned up fairly well (better than the pic shows - did another round of cleaner)....The ribbon is done for....Any ideas on how to fix the ribbon cable? Can I some expose more "leads"?

Maybe I will get lucky and its just the corroded connector...not a shorted out backlight.

Thanks
Chris

[SolomonMan]

Re: Led24a45rq

All,
For the record I used some electrical connection cleaner (WD40 brand). Used it in the past with some other electrical connections and have had great success especially with small electrical component repair (Ipads,cell phones,etc).

The Panel connection is very clean now and ready to be reconnected.

Unfortunately the ribbon cable (this is very thin stuff) did not fair so well...It looks like from the heat and corrosion (resistance) the pins were damaged (I do not believe from the cleaning but it was more or less from arcing/corrosion in the past). The TV appears to have been in a damp area (probably a basement or maybe it was stored there a while) as the TV shows some minor dusting of maybe mold spores around the speaker area/bottom of TV.

So I went looking for new cables for this model of TV and Ebay has a guy out there that is selling his cables as a complete set for this TV but his panel light connections do not appear to be like mine...his are actual connectors.

So I am looking at how to repair this ribbon cable (Can I cut the bad off, then tape off, and sand off the top layer of the ribbon cable...This cable I do not believe can be scribed (knife) and stripped...its thin....Or is there a place that I can pick up ribbon cable?

Thanks
Chris

[vinceroger69]

Re: Led24a45rq

https://www.ebay.co.uk/itm/Cable-Rub...-/273835338931
https://www.aliexpress.com/af/e31722...chText=e317223

[diif]

Re: Led24a45rq

The damaged end can be cut off and using either fine sandpaper or a scalpel the white insulation on top of the copper is then sanded or scraped away.

There isn't always enough spare cable to do this though.

I would think it far easier to buy a new cable. It doesn't need to be for that particular TV, they are available form several places (Mouser, Digikey, ebay, Aliexpress...) but you will need to know the pitch (0.5mm and 1.0mm are the most common) the distance form the centre of one contact top the next. Take note if the connections are on the same side of the cable or on opposite sides. These are sometimes referred to as forward or reverse. Obviously you'll need it's length too.

[SolomonMan]

Re: Led24a45rq

Guys,
Thanks for the information on the ribbon cable...did not know all the ins and outs on ribbon/flat cable.

Has anyone seen this type of thing before...the corrosion etc causing the TV not to backlight ...or could I still be dealing with bad backlights?

Thanks
Chris

[SolomonMan]

Re: Led24a45rq

All,

Hope this post finds everyone well!

I had some time to look at this TV some more...After getting another used cable (and a bunch of other small parts for the TV) from ebay I put the TV back together and was getting similar result as I was previously...A screen for a split second after pressing the power button and then it shutting the screen down.

So I figured a BackLight Strip was a logical next step as the connection looked like it had suffer some abuse in the past. (Corrosion/heat/burnt).

R_J mentioned that it may have a short. Unfortunately this set does not leave much in extra cable and testing things is fairly difficult...Boards are mounted to the back of the plastic bezel.

So I finally took the panel apart ever so carefully. Upon removing the back light strip I unfortunately snapped the backlight strip (Glue/Tape and corrosion was not my friend). Anyways I found some decent amount of corrosion around the backside of the backlight connector (not visible unless the backlight was removed) and also a fair amount on the backlight strip in the center of the strip.

Pics are included but please note this is after some probing to remove the excess green corrosion.

Anyways I have located a good backlight strip in a few locations but wanted to throw this out to everyone to get a feel that it was probably the build up of corrosion on the backlight strip/connections (corosion causing the short (Thanks RJ) and maybe some guidance/tips on installing a used backlight strip...It appears mine had some glue/metal tape possibly on the back of the strip. Assuming a used backlight strip is my only option is there anything I need to do during installation to avoid a short/get it back together successfully.

Also how does one test a LED Backlight Strip...I have a LED Tester but I cannot seem to get it to light all LEDs nor get them to light exceptionally large amounts on the strip...maybe 10-15 max...and some I cannot seem to get to light at all...some just to flicker.

Thanks again everyone for the help,
Chris