Back light problem

[snipersquad100]

Re: Back light problem

Funny you should say that cos ive noticed those two caps have been changed
b4 by someone, the soldering is not the best. I will reflow them now see if it fixes it or see if maplin got any tomorrow.

[vinceroger69]

Re: Back light problem

this is from another thread
I've seen a few small screen sets with duff backlights. I'm pretty sure it's dry connections . I've just changed c230/231 5pf 6kv caps it appears to be fine. I wish I'd examined them under a magnifying glass for dry joints before I removed the old ones as I can't see anything wrong with them. Unless they are breaking down under load might be worth a check/replace just in case.

it looked correct lol

[snipersquad100]

Re: Back light problem

That's the same one lol 10-2

[snipersquad100]

Re: Back light problem

Thank you vince

[vinceroger69]

Re: Back light problem




!!! dont down load wrong schme !!!

[snipersquad100]

Re: Back light problem

is it worth getting the reading across the pads.

[snipersquad100]

Re: Back light problem

this board is vestel 17IPS10-3 the schematic is 10-2.
wait just found c164 and its unpopulated cap.

[snipersquad100]

Re: Back light problem

I cant see c164 to save my life, on that schematic its a 220uf/200v should stand out like a sor thumb.

[tom66]

Re: Back light problem

Should be OK for now.

[snipersquad100]

Re: Back light problem

Ok will do. Any more pics needed b4 I put it back together.

[tom66]

Re: Back light problem

We don't need board layouts at the moment with, uh... "schematics" (if you could call Vestel's attempt one.) Check 150V. Across C164, I think.... (schematic completely unclear.)

[snipersquad100]

Re: Back light problem

where do I prob for the 150v?

[snipersquad100]

Re: Back light problem

Hope you can piece it together.

[tom66]

Re: Back light problem

This PSU uses 150V for backlight inverter. I would check what this does when fault occurs.

[budm]

Re: Back light problem

I am not sure if the 17IPS10-2 SCH is close to your -03 or not, but it may help.
I download this from TOM66 website.

[snipersquad100]

Re: Back light problem

yes screen is apart, give me have hour to do the underside of the pcb.
yes this is a tuff one, Ive never worked on a psu/inv combo b4. if I could be sure its the psu/inv and not the back light or something else id buy a new board.

[budm]

Re: Back light problem

Did you take the screen apart?
Pictures of the bottom side of the power supply board? I need to be able to see good clear pictures of the components on the bottom side of power supply board to see how the inverter transformer being driven.
This is going to be tough, there are so many pins on the power supply/inverter board connector that goes back to the main board.

[snipersquad100]

Re: Back light problem

[snipersquad100]

Re: Back light problem

Sorry had to use flash as its dark. If you need better ones I'll have to take em in the morning. Thanks

[budm]

Re: Back light problem

I need good clear pictures of that power supply/inverter board combo top and bottom side. That high voltage inverter transformer is not likely to be running from 24V power supply but more likely from the PFC Voltage booster circuit that supplies about 380~400VDC to drive that transformer through MOSFETs. I cannot tell until I get to see better pictures to figure out how this board works.