JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

[PL519]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

yeah, you´re damn right. It was just a "blip" in my old brain and i wanted a quick and dirty realisation.
BTW, can you tell me how to get access to the led-stripes inside the panel? Doesn´t seem to be an easy process without damaging it.
TIA,
Wolf

[ReeceyBurger123]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

Its ghetto but it works at least, maybe a little more isolation of the terminals of the wires will make it more safe but good overall idea to test it. Thanks for the feedback too

[PL519]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

Hi,
i´m working on exactly the same chassis, only difference it´s a telefunken brand type D42F182N2, age: 2 years and two month, just out of warranty. Customer told me that screen went totally black from one second to the other. First assumption was backlight LED´s. With the information from ReeceyBurger123 (thanx to him) about the voltages i built this nasty chain of high current led modules from Citizen. They are normally driven by 350mA constant current which leads to a drop-out voltage of abt. 33V. 5 of them in series could well fit the output voltage of the LED driver. I applied the chain to the driver, switches the set on and voila: all modules lit, changing their brightness in three steps during boot up process. ReeceyBurger123´s info abt. voltages verified. So this could be a good method for quickly testing the driver or the led´s in the panel. Maybe helpful for somebody?!
Greeting,
Wolf

[budm]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

I found some SCH for the the 17IPS20 series (4 versions that I found) but none match his board layout.
The SCH I look at has to feedback error signal to tell the main board if BL-ON is present at the power supply board or not, or any error signal to tell the main board if the LED drivers are not functioning.
But you probably right that the Boosting circuit is not working at this point, he can get the spec sheet of the IC to do some Voltage testing or get the new IC since you already experience with this failure in the VESTEL.
BTW, I still do not like those 3 LEDs which are not on, it means they are not in the same condition as the rest of the other LEDs.

[tn245]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

Thanks for all the suggestions guys. I'm going to have to wait until tomorrow to do the tests suggested. Will report back.

[ReeceyBurger123]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

Im quite sure he would be, these mainboards if the Blon was at fault im sure lock out and fail to give standby Led. Common fault is the Ic that drives the fet fails absolute crap Tv's Budm.

[budm]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

I wonder if he is getting the BL-ON to start the booster circuit or not.

[ReeceyBurger123]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

Led drive voltage on 17ips20 for Ves400:

Backlight on Low: 162v Dc

Backlight on Med: 165v Dc

Backlight on High 169v Dc

[Diah]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

123V and it stays there.

you need to test the Diode of the LEDS especially the off on, if the Diodes should read 785-750 any less than this average Bad Diode it lights but it limited the passing currents to the next one.

[budm]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

I expect it to be around 150~160 range.

[ReeceyBurger123]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

Im currently doing the same panel now, I actually have 2 failed O/C Leds causing no Bl though. Will let you know what the drive voltage is when I fix mine.

[ReeceyBurger123]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

Well if he said they light with the meter probably means they are ok.... If one was shorted the meter will beep or show 0 ohms.

[budm]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

123V and it stays there.

Please try it again but without the LED connector in place.
Also can we get the good clear pictures of the bottom side of the board?

The Diode (boosted Diode) on the top right of the board next to that small boost inductor L5201 tested OK?
https://www.badcaps.net/forum/attach...4&d=1458058395

[vinceroger69]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

i would change the three leds which budm has pointed out maybe there on the verge of failing, in not sure if its worth changing that led strip for a diffrent location and see if the fault moves if it does it has to be that strip i guess.

[tn245]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

So if you leave the meter probes between the two legs of the booster output filter cap (47uF200V) laying on its side next to the LED connector then turn on the TV, do you see it jumps much higher than 105 VDC and then drops down to 105Vdc later on?

123V and it stays there.

[budm]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

So if you leave the meter probes between the two legs of the booster output filter cap (47uF200V) laying on its side next to the LED connector then turn on the TV, do you see it jumps much higher than 105 VDC and then drops down to 105Vdc later on?

[tn245]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

Budm, you're right those three don't light up under the TVs own power, but they do light up when powered up separately.

ReeceyBurger I will check out that controller thank you.

[budm]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

I see three of the LEDs are not on, are you sure they are not shorted out? If they are shorted out then the boost circuit will not be on, the 105V is the feeding Voltage to the booster circuit to raise it up higher by the booster. If those 3 LEDs are shorted out it will trip the over current protection circuit.
BTW, please also up load the pictures of the bottom side of the power supply-LED driver board.

[ReeceyBurger123]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

I would say replacing the controller will likely fix the issue but you can replace the fet too if you want.

[ReeceyBurger123]

Re: JVC LT-40DJ51J - Vestel 17IPS20 - LEDs very dim

Think this is the kit you will need:

http://www.ebay.co.uk/itm/VESTEL-17I...8AAOSwHPlWesfB