Baird X47DTV power supply issues

[gilly1984]

Re: Baird 47"

You was right tom, i have found a bad mosfet, and a bad diode (The diode looks like a mosfet) Is there anything else i should check before ordering parts?

[tom66]

Re: Baird 47"

The controller IC is likely damaged, check the gate drive pin going to the MOSFET for shorts to ground or Vcc... post a pic if you need one.

What is the LCD panel used in this TV?

[gilly1984]

Re: Baird 47"

Checked what i believe to be the controller ic, and it checks out ok, on diode test it gives me 150+ to ground and 650+ to vcc.

Not 100% sure if i used the right pins.

Also included is the dead mosfet and dead diode (diode is the 2 pin one on the heatsink)

And the last pic is a capacitor which has a crack in it, will it still be ok to use?

Sorry about the pics, using a camcorder with no macro.

[tom66]

Re: Baird 47"

Try on ohms but I think your controller IC is shot. It is very common as the MOSFET will pass ~325V straight into the drive output pin.

The other device is an inrush NTC, not a thermistor. It says 2.5 ohm which should be its cold resistance, so measure it when it's cold and check it's about 2.5 ohms (usually 20% tolerance.)

[gilly1984]

Re: Baird 47"

Try on ohms but I think your controller IC is shot. It is very common as the MOSFET will pass ~325V straight into the drive output pin.

The other device is an inrush NTC, not a thermistor. It says 2.5 ohm which should be its cold resistance, so measure it when it's cold and check it's about 2.5 ohms (usually 20% tolerance.)

Right again i believe, The ic from drv pin to gnd gives me 149 ish ohms, but on the other working psu i get no reading.

Gonna start getting expensive

New psu only about £30, but thats no fun.

[gilly1984]

Re: Baird 47"

Is there anyway of rigging it up for just the 24 volts? As this board only supplies power to the inverter on the right side (When looking from the back.)

[tom66]

Re: Baird 47"

I suspect they use two PSUs because one isn't capable of the full output.

[gilly1984]

Re: Baird 47"

I suspect they use two PSUs because one isn't capable of the full output.

Yh, i have wired both inverters upto the working psu and the tv works, but only for about 15 seconds.

When its about to switch itself off i get weird lights (round bright bits.) at the top of the panel, i will show you a pic later. Its not the panel though, its the backlights, could that be the psu struggling to keep the lights on.

[tom66]

Re: Baird 47"

Most likely the PSU is entering current limit mode and I wouldn't be surprised if you start seeing dimming or flickering from the backlight lamps.

[gilly1984]

Re: Baird 47"

You're a genius mate, will get pics up soon and show you what i mean.

[gilly1984]

Re: Baird 47"

Is this the ic i need? The only thing it says on this one is 1377b.

http://www.digikey.co.uk/product-det...SCT-ND/2121280

[tom66]

Re: Baird 47"

Looks good to me.

[gilly1984]

Re: Baird 47"

Any cheaper places to order from? Prices are ok but shipping is stupid.

[tom66]

Re: Baird 47"

Any cheaper places to order from? Prices are ok but shipping is stupid.

http://www.ebay.co.uk/itm/1PCS-PWM-C...item3cbefa9aa3

or,

http://www.ebay.co.uk/itm/NCP1377BDR...item1c27719f10

or,

http://www.ebay.co.uk/itm/ON-NCP1377...item3f19cae6c9

[gilly1984]

Re: Baird X47DTV power supply issues

Can this ic be damaged with a soldering iron? And i'm not the best at smd.

[tom66]

Re: Baird X47DTV power supply issues

SMD is easy.
http://www.youtube.com/watch?v=3NN7UGWYmBY

It is easier than through hole when you get experienced.

[turbozutek]

Re: Baird X47DTV power supply issues

SMD is easy.
http://www.youtube.com/watch?v=3NN7UGWYmBY

Everything I learnt about soldering, I learnt from a video where they couldn't even pronounce the word correctly.

SMD is easy though and I'd agree sometimes much quicker and simpler than through hole stuff. This little chip looks intimidating but using the methods in the video (if not the butchering of the words in it) you won't go far wrong!

[gilly1984]

Re: Baird X47DTV power supply issues

Tom. not sure of the panel as can't find model number on it. but the main board is LG and the tcon is philips. does that tell you the panel make?.

[tom66]

Re: Baird X47DTV power supply issues

Yeah, it's an LG-Philips panel (on par with Samsung panels), quite nice. Main board is LG too??

[gilly1984]

Re: Baird X47DTV power supply issues

Yeah, it's an LG-Philips panel (on par with Samsung panels), quite nice. Main board is LG too??

Yep, tcon says philips, can see it through the vent on the metal plate covering it.

And the main board is this,

http://www.lcd-plasma-parts.co.uk/in...roduct_id=2906

Can i get cash back in parts if all else fails with parts for it.