Vidao 32 inch lcd tv powers on but no backlight or picture

[shelby5041]

hi

i have this vidao cheap lcd tv model 32A60

it powers on....green power light comes on

however there is no backlight and did flashlight test and has no picture

i tested some of the voltages and i get

12v pin= 6v
24v pin= 6v
5v pin= 5v
pson pin= 4.4v

i tested the 5 caps near these pins 1000uf and 470 uf using a esr meter and in circuit they seem to test and look ok

the only thing i could see otherwise is the large 450v 16uf cap in the center of the board is bulged on top

could this be the issue?

here is a photo of the power supply board

thanks

[dick_barton]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

Previous thread which may be of some help to you:-

I replaced one switching Transistor 2n4401 (Q8) which is connected to the opto-isolaters and it works great now.

https://www.badcaps.net/forum/showthread.php?t=40142

[ReeceyBurger123]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

Thought you said the Psu was blowing up in another thread ?

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

i have 2 threads

same board 2 diff problems trying to get one to work to repair vidao 32 lcd

one blows up main fuse instantly...no matter whats plugged into ps

and the other gets low voltages

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

previous thread not same issue as mine

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

i just looked at previous thread its possible cause of mine his is intermittent mine is 100% low volts all the time so maybe i will swap q8 from one board to the other just for the heck of it and see what happens

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

one question i have though....the large 450v cap is bulged ....is this an issue or not really?

[dick_barton]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

I don't know if anyone can tell from the photograph but if you can see that it that it has bulged, then it should be changed.

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

thank you

it is definitely bulged

the photo i posted is generic photo

one questionb....how long do i have to wait until i can desolder the large cap safely to replace...i want to swap from another board

without getting zapped...

thanks

[dick_barton]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

Measure the voltage across the two pins and when it is near to 0V it is safe to do so.

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

Update I replaced the 450v cap and q8 and no change still get low voltages

Same readings as before

Any ideas?

[budm]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

Are you getting close to 400VDC between the two legs of that main filter cap? If the PFC Voltage booster is not working the 12v/24V SMPS will not function correctly.
BTW, the cap is only 16uF? Not 160uF?

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

sorry its 68uf not 16uf

and i have not checked for 400v while in circuit

is that something i can do safely in circuit?

the cap i replaced was bulged....i replaced it with another cap from spare duplicate board i had

[budm]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

You should at least plug what ever you are working on into GFCI outlet at the very least.
Just have to be careful and not touching anything on the board with your hands or body.

[budm]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

If the boosted Voltage is present, then you should check the capacitance of that gray rectangular cap off the board, and if that checked out OK, then we need to find out if the SMPS IC for the 12V/24V has VCC to run.

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

update

ended up spending too much time getting nowhere over 20 hrs so i bought another power supply for only $15 on ebay shipped and just got it and installed it and tv works great now

thanks to everyone who tried to help

[budm]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

Thanks for the follow-up on the outcome, $15 is very good price.

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

yes 15.00 including shipping was a great price

i got the tv for $5

my friend had a property that a tv shop rented and he didnt pay rent so he evicted him and said i could come see what he left behind

tons of older lcd tvs and a few led lcd tv but all were just mix and match taken aprt etc..also lots of misc tv boards laying around everywhere but most were damp from the water ..the shop was in a bad area of detroit and was raining inside and most just junk but i was able to find a few that i considered fixable....i got this one fixed and anohter one actuall powered on fine no repair needed

i got them for $5 each



thanks

[shelby5041]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

also i cant find any specs for this ultra low end tv

anyone know the specs?

vidao 32a60

[budm]

Re: Vidao 32 inch lcd tv powers on but no backlight or picture

http://www.sibrandssupport.com/

http://www.sibrandssupport.com/32A60.html

https://cdn.badcaps-static.com/pdfs/...a2cb736687.pdf