TCL 50S421 power supply interchangable?

[x_orange90_x]

I picked up a TCL 50S421 yesterday that appears to have a power supply issue. I get absolutely nothing when plugged in, not even a power indicator. I was curious if a spare power supply I have from a 55S451 would possibly work in it, at least for testing. The boards are physically different but the only two connectors are on them are identical. What is the likelihood that the 451 PSU would power up the 421 and NOT cause any harm?

Here are links to the two boards:

https://www.shopjimmy.com/tcl-08-l12...-supply-board/

https://www.shopjimmy.com/tcl-30805-...-supply-board/

I've read about other brand tvs being able to use boards from other models and even different brands with completely different boards. I just want to see if this tv is good before investing time and resources into it.

[Storyteller12]

Re: TCL 50S421 power supply interchangable?

There is no legend on either board to compare voltages and pin out. It may work but without confirming the pin out and backlight output voltage I wouldn’t try

[x_orange90_x]

Re: TCL 50S421 power supply interchangable?

Really the only plug pinout that matters is the one going to the main, right? The power cord wouldn't be different. Would the legend possibly be on the main board side of the cable?

Attached are photos of the back of the plug on the main boards.

[Diah]

Re: TCL 50S421 power supply interchangable?

Attached are photos of the back of the plug on the main boards.

you are diving with experiment could end to catastrophic result... because at the end 55 size BL circuit will burn the 50 LED BL

the correct way.. take yours Original and put it alone on the table... plug it in wall and check at cold side if you have any reading DC V. photo of the boards in high resolution will help to guide you where to test

[EazyBone]

Re: TCL 50S421 power supply interchangable?

I just fixed both these tvs, I only have the 55 right now. It supplies 82v to each LED strip. I would assume the smaller TV would supply 6-12v less to each side

Essentially you would be putting more power to the LEDs then needed.

I couldn't tell you if bad idea but I'd assume it would be.



@ diah, what if he just disconnected the LEDs so they aren't in circuit. If the main board connected is same voltages as previous one would be not just be able to test that the power light at least comes on? In my experience these tvs will show picture even if bl circuit is out.

I would think if bl disconnected it would at least show if TV might work no?

[x_orange90_x]

Re: TCL 50S421 power supply interchangable?

you are diving with experiment could end to catastrophic result... because at the end 55 size BL circuit will burn the 50 LED BL

the correct way.. take yours Original and put it alone on the table... plug it in wall and check at cold side if you have any reading DC V. photo of the boards in high resolution will help to guide you where to test

Thanks for the reply! Ya the extra LEDs in the 55" was my real concern as far as voltage goes. If you click on the pictures in those SJ links you can zoom in on them in high res. It won't let me download them to my phone.
I did read that someone found a ceramic capacitor to be completely burned on their same model PSU, so I'm going to look at caps first. I haven't opened it up yet but I will today.

@EazyBone ya it might be a bad idea, but if it's only say 6v and it's 8 LEDs per strip in the smaller tv, that's .75v more per diode. I don't image that would fry them, but if it's 12v more than that's 1.5v which would be quite a bit more.

Side note, in regards to my other thread about the 55", I received the correct replacement main board and will be putting it in today. Fingers crossed that it works.

[Diah]

Re: TCL 50S421 power supply interchangable?

Thanks for the reply! Ya the extra LEDs in the 55" was my real concern as far as voltage goes. If you click on the pictures in those SJ links you can zoom in on them in high res. It won't let me download them to my phone.
I did read that someone found a ceramic capacitor to be completely burned on their same model PSU, so I'm going to look at caps first. I haven't opened it up yet but I will today.

why need external LINK to show the issue.... as you upload it the pins you can do.... SJ not all region allowed to browser their page.

[x_orange90_x]

Re: TCL 50S421 power supply interchangable?

I just fixed both these tvs, I only have the 55 right now. It supplies 82v to each LED strip. I would assume the smaller TV would supply 6-12v less to each side

Essentially you would be putting more power to the LEDs then needed.

I couldn't tell you if bad idea but I'd assume it would be.



@ diah, what if he just disconnected the LEDs so they aren't in circuit. If the main board connected is same voltages as previous one would be not just be able to test that the power light at least comes on? In my experience these tvs will show picture even if bl circuit is out.

I would think if bl disconnected it would at least show if TV might work no?

I like this idea... But would potentially higher voltage going to the main board damage it even if the BL are unplugged?

[EazyBone]

Re: TCL 50S421 power supply interchangable?

Yea I hear ya. Looks like the 55 has 15 LEDs and 14 LEDs for the 50 inch. Ok believe they are all 6 v

[Diah]

Re: TCL 50S421 power supply interchangable?

why we keep talking on theory LOL.... with out BL socket in you will have error pin goes high.. the right way only take out yours Original and we tell you how to check it as standalone... if all V it produce correct then MB...LOL

[x_orange90_x]

Re: TCL 50S421 power supply interchangable?

Update!

So after cleaning the screen (it was covered in film), I can see an image on the screen. So the backlights are bad.

Thanks for the help guys! I really appreciate it!

[EazyBone]

Re: TCL 50S421 power supply interchangable?

Invest in a LED tester.

You said you don't even get a power signal but now you do? Backlights can't cause that can they?
The BLs are only like 10-15$ so easy peesy. Glad it's figured out

[x_orange90_x]

Re: TCL 50S421 power supply interchangable?

Invest in a LED tester.

You said you don't even get a power signal but now you do? Backlights can't cause that can they?
The BLs are only like 10-15$ so easy peesy. Glad it's figured out

I couldn't see the indicator light because the little clear piece is discolored. After removing the cover I could see it was lit. I've done back lights on several tvs so I know what I'm in for! Thanks again!

[x_orange90_x]

Re: TCL 50S421 power supply interchangable?

Update:

I put in new backlights last night and tested before reassembly. Appeared to work fine. Placed the panel back in and managed to crack it. For anyone else who wants to do this, be VERY VERY careful with the black tape running along the edges of the panel. They taped it to the side COFs for some stupid reason. I was removing the tape and it tore one of the tabs almost completely off effortlessly. I attempted to seat it back in place with tape on the backside and a couple paper shims to keep pressure on it. Well I assume one of the paper shims got under the panel when I put the frame back on and that was enough to crack it. Incredibly cheap build. They make these things like dollar store USB cables. Lightweight, flimsy, and fragile.

I'm out $13 and about 90 minutes of my time. Not terrible, but very disappointing.