hitachi 32HXC01U no backlight pl501 has 24v

[wreksta]

hitachi 32HXC01U no backlight

hi all got thguis set in and has a picture if you shine a torch
backlights wont come on

ive measured pl501 connector ande i get 23.9 on the black wire and 00.1 on the red wire this seems strange to me

ive checked led array and found one broke led but no short

can any one elaborate on this for me

[ReeceyBurger123]

Re: hitachi 32HXC01U no backlight pl501 has 24v

If you found a broke Led that will cause the whole lot not to work, more than likely the Led has failed Open not Short. These are wired like christmas lights one out all out, you will need to replace that Led as with it not being present/broken it wont complete the ciruit so non will light.

[wreksta]

Re: hitachi 32HXC01U no backlight pl501 has 24v

cant i bypass it mate for testing purposes
if soi how please

[ReeceyBurger123]

Re: hitachi 32HXC01U no backlight pl501 has 24v

You can with a zener diode normally a 3w type you will need to reverse bias the diode though. Best bet is to get a new Led tbh what type of strip is it can you take some photos ?

[wreksta]

Re: hitachi 32HXC01U no backlight pl501 has 24v

i dont have any photos mate but these are them here

[ReeceyBurger123]

Re: hitachi 32HXC01U no backlight pl501 has 24v

Ahh right, internet says this is an edge lit tv but this is a full array type, which Led is faulty ?

[tom66]

Re: hitachi 32HXC01U no backlight pl501 has 24v

Oh one of these again
A 68 ohm resistor (3W, no less) also works, the circuit is constant current driven, just need a reasonable resistance.
Once you fix this set modify PSU and remove all but one of the 0R20 current sense resistors, SMD on the bottom, this will reduce LED current by 40%, which improves lifetime. (the drop in brightness is barely noticeable.)

[ReeceyBurger123]

Re: hitachi 32HXC01U no backlight pl501 has 24v

These full array types are dropping like flies just done an Lg 42" (thread to come) with the same failure more Led Trash !

[wreksta]

Re: hitachi 32HXC01U no backlight pl501 has 24v

thing is ive tested all the leds and work i have the right voltage so why are they not firing
any ideas on this please

[ReeceyBurger123]

Re: hitachi 32HXC01U no backlight pl501 has 24v

So you have tested each individual Led ?

[ReeceyBurger123]

Re: hitachi 32HXC01U no backlight pl501 has 24v

You said "one broke led" that one broke led will cause the whole lot not to work, so is there a broken led ?

[tom66]

Re: hitachi 32HXC01U no backlight pl501 has 24v

Using diode test mode a good multimeter will make an LED light up.
If not, use a 3V coin cell battery.

[wreksta]

Re: hitachi 32HXC01U no backlight pl501 has 24v

my meter lights them up mate and everyone of them tested works accept the broke one ive removed it and shows no shorts but still lights wont fire

anyt ideas

i get 23.9v going from connector to the the led array

so shouldnt these light up

[tom66]

Re: hitachi 32HXC01U no backlight pl501 has 24v

They're in series - so of COURSE it won't work when you remove one of them!
It's like Xmas lights - one open circuit, none work.
That's why LED TVs suck for repairing.

[wreksta]

Re: hitachi 32HXC01U no backlight pl501 has 24v

forgot to say ive replaced that led mate thing is do i need the screen connected for the leds to fire as been testing with bare frame only with power and main conected

[tom66]

Re: hitachi 32HXC01U no backlight pl501 has 24v

Maybe you put the LED the wrong way around.

[ReeceyBurger123]

Re: hitachi 32HXC01U no backlight pl501 has 24v

What type of led have you replaced it with and is it soldered in the correct way ?

[budm]

Re: hitachi 32HXC01U no backlight pl501 has 24v

11 LEDs connected in series for each strip, 24VDC is not going to be enough to light them up.
Did you have the meter attached to the connector to see if the Voltage did jump up higher than 24VDC and then settle down to 24VDC?
More likely the two LED strips are connected in series so that will be 22 LEDs in series, the Drive Voltage will be much higher than 24VDC.

[tom66]

Re: hitachi 32HXC01U no backlight pl501 has 24v

I had the same panel and it used 65V.