Backlight 50HYT62U

[TheBugger70]

hi trying fix cousins tv with no backlight tv is hitachi 50hyt62u i beleve the power suply is vistel 17ips20. i checked power coming out the boared to leds and was getting meter jumping from around 2v to 9v so i disconected leds from bored and was still getting the same. i tryed testing the leds wen unpluged from bored but wasnt able to get any reading. im wondering if the power detects that the led's have failed it wont put the rite power out or if it is a fault with power bored is it posable to test the leds with multimeter the way i tryed by disconecting from power supply and testing from the conector rather than strip screen. thanx for any help

[Diah]

Re: Backlight 50HYT62U

so is this mean you have approved you can see picture with tourchlight and can hear sound?? if yes .. ready yours metter on LED+ and LED- then plug the TV in wall see the reading going high and then down?

[TheBugger70]

Re: Backlight 50HYT62U

yes iv checked seen i have picture, i tested power been sent to leds its low gose from 2v to 9v jumping back nd forth it dont get high as id xpect to power the leds. but i wasnt sure if sent low power 1st then if leds were ok give the rite voltage. i tryed test the leds with multimeeter but got no reading i would of though when unpluged from power suply and tested i would of had some reading and was thincking it may be leds. thanx fr reply

[Diah]

Re: Backlight 50HYT62U

show us high resolution focused photos of the area of the LED socket on PSU from top and down side.. by go Advanced and upload over here.

[TheBugger70]

Re: Backlight 50HYT62U

will get pics done now be 5 or so mins

[TheBugger70]

Re: Backlight 50HYT62U

think ive got pics done was stuck how to upload them

[Diah]

Re: Backlight 50HYT62U

messure black probe on tv chassis and the red on pin 1 of socket cn501. then plug in wall.
BTW LED socket should in place

[TheBugger70]

Re: Backlight 50HYT62U

i done that erlyer i got reding jumping between 2v - 9v i wil try get vid nd post it. sory took awhile to get back hata nip shops. dont think i can upload video of reading but it jumps from 2 to 9v back and forth

[Diah]

Re: Backlight 50HYT62U

the red wire of LED it look touching the Tv chassis..??
this is the schematic of the PCB see page 3 and follow voltage of LED VCC.. tell where you can find V.

[TheBugger70]

Re: Backlight 50HYT62U

the wires are just short of a inch away from the bored its just the way looks on pic. thanx will have look at that now and see what can work out

[Diah]

Re: Backlight 50HYT62U

the wires are just short of a inch away from the bored its just the way looks on pic. thanx will have look at that now and see what can work out

BTW did you messure the pin on the socket which connected with MB. BL-ON-Off are high or low while Tv powered on??

[TheBugger70]

Re: Backlight 50HYT62U

i checked for voltage while tv was on with led pluged in and with out led pluged in i got the same jumping from 2 to 9v im not sure what you mean high low, im trying to work scmatic u sent out gona go prod about with meeter just trying to understand scmatic lol. thanx fr help

[Diah]

Re: Backlight 50HYT62U

i checked for voltage while tv was on with led pluged in and with out led pluged in i got the same jumping from 2 to 9v im not sure what you mean high low, im trying to work scmatic u sent out gona go prod about with meeter just trying to understand scmatic lol. thanx fr help

not this what i mean.. the socket which connected between main boards and power boards pin 5 labled as BL_ON-OFF this is signal from Main boiards to turn on the backlight on and off.. messure it with ref to tv chassis .. we want to know that MB send this signal or not

[TheBugger70]

Re: Backlight 50HYT62U

ok il find and test that now

[R_J]

Re: Backlight 50HYT62U

Connect your meter between ground and pin1 of cn501 (The RED wire) then plug in and turn on the tv. This voltage should jump to 80v or higher and if there is a fault it will drop to 24v
The picture in post #8 shows you checking pin7 (black wire) which is the led return.

[Diah]

Re: Backlight 50HYT62U

good point... i asked him this early at post#7 ... he messure led- to chassis... lol
also on the photo i can see black burn close to the red wire socket

[nomoresonys]

Re: Backlight 50HYT62U

maybe unplug the backlights and see if there's stable voltages on powerboard if not tried yet.

[cheeky2]

Re: Backlight 50HYT62U

A small point but the output lead from the power supply feeding the leds you will find that the red wire on Vestel TV's are -ve and the black wire is +ve!
I don't know why Vestel did this but that's probably why you are also getting low voltage. Bizzare but true!
So connect the black meter wire to chassis and the red wire of the meter to the black wire coming out from the PSU. Making sure you have set meter to dc voltage!
If you don't get a voltage of around 120V plus then connect red and black leads to the output connector from the psu.