Baird X47DTV power supply issues

[tom66]

Re: Baird X47DTV power supply issues

Not ALL flux is conductive. The good stuff isn't. But the cheap stuff in cheaper solder tends to be.

[gilly1984]

Re: Baird X47DTV power supply issues

Just found this on another site on google.

"Used flux is hydroscopic (absorbs moisture from the air) and can lead to bridging conductivity between pads and traces, at the least adding stray capacitance.

This is why commercial boards are thoroughly cleaned of all excess and used flux, boards can are often rejected in the QC phase just for flux residue being present."

So good call there tom.

[gilly1984]

Re: Baird X47DTV power supply issues

Shit. Will get some tomoz.

Cheers.

[tom66]

Re: Baird X47DTV power supply issues

Your flux is conductive - you need to clean it with some isopropyl alcohol before it fries more stuff.

[gilly1984]

Re: Baird X47DTV power supply issues

Here is a pic of it tom.

[gilly1984]

Re: Baird X47DTV power supply issues

not sure. its a Panasonic HD series cap.

its was definately a short I created with solder as there was splash marks behind the psu on the chassis from the flux on the solder. at first I thought it arced out onto the chassis but the legs were no where near it.

[tom66]

Re: Baird X47DTV power supply issues

Unlikely... MOSFETs are all or nothing, it's rare to wound them. Something else is killing them. It could be the 180uF not soldered in properly. This would cause spikes or transients. Also is the 180uF low ESR?

[gilly1984]

Re: Baird X47DTV power supply issues

same psu.

remember that pop I heard, well there was a nice burn mark under the fet, not the fet I replaced, but the fet attached to the heatsink that the hyperfast diode was attached to.

I must of shorted it when attaching the heatsink back on, that first pop damaged it, then next day the surge of electric being switched back on took it out completely.

I just happened to have 2 spares on that bush psu, stole one off it and fitted it to the Baird, soldered it all back together and 2 legs were shorted, removed the solder, cleaned it up a bit and resoldered, checked for shorts and yay, there were none.

plugged it in and no pop noise, pressed the power button and she's alive again lol.

bought a surge protection plug, just in case lol.

[tom66]

Re: Baird X47DTV power supply issues

On same PSU or other PSU?

[gilly1984]

Re: Baird X47DTV power supply issues

Mosfet dead, but not the one i replaced, now its the other one, near where i replaced the hyperfast diode.

What the hell?

[tom66]

Re: Baird X47DTV power supply issues

Test the MOSFET. Did you repair that trace? Cap properly soldered in?

[gilly1984]

Re: Baird X47DTV power supply issues

unhappy.

watching TV this morning just fine, electric ran out and TV went off, put the electric back on and as soon as I did I heard a bang.

opened TV and the fuse has completely shattered.

checked for shorts but it seems fine still.

stupid question here but is it because I used a 2A fuse? and the surge of electric coming back on blew it?

scared to stick another fuse in now.

[tom66]

Re: Baird X47DTV power supply issues

No need. It died due to poor 180uF, unlikely to be heat. If you open it up again for service, I would replace that other primary cap on the other PSU.

[gilly1984]

Re: Baird X47DTV power supply issues

Thats exactly how it looked, fake.

Oh, and no i didnt glue it down, the heatsink is over it, no where for it to move.

Thinking of modding the back to put a 120mm fan inbetween the psus.

[tom66]

Re: Baird X47DTV power supply issues

Oh, high Hz does not make it look better, trust me. I have fixed a Samsung 100 Hz LCD and kept it. We all unanimously agreed to turn off the feature after about 5 minutes; it made everything look fake.

[gilly1984]

Re: Baird X47DTV power supply issues

To be honest i couldnt tell the difference in quality between the 37" hannspree we had compared to the 40" sony, now it looks just the same on the 47" Baird, just bigger.

Although i can see a big difference in the menu options. The sony had lots to play with, including auto backlight.

The only time i have seen a major difference on an lcd tv is when i went to a friends of a friends home to fix a pc, she had a Philips tv, it looked like i was watching real life lol, it was weird, maybe it had high hz or something? No idea, i wasnt into tvs at the time.

[tom66]

Re: Baird X47DTV power supply issues

Did you glue it down? I would glue it down, then solder (makes it easier.)

I bet you'll find you like the picture on the Sony 40" more, due to the better video processing. My argument with bigger screen sizes ... is to sit closer to the TV. My 24" monitor looks the same as a 32" from 6 feet. etc.

[gilly1984]

Re: Baird X47DTV power supply issues

Quick pic of bodge job.

And the small ruby next to it is what i put in too, original looked very slightly bulged.

[gilly1984]

Re: Baird X47DTV power supply issues

Not sure, not much information about it about.

Gonna guess its a 720p though, just because of the cheap mainboard.

Just put it in the front room now (bye sony 40"), looks no better than watching the last tv, just bigger.

Can't thank you enough tom, a real credit to badcaps.

Just this philips to sort now, bought a new cap for it but that didnt fix it.

Anyway, thats another day, i will update the philips thread when i have the screw drivers out.

[tom66]

Re: Baird X47DTV power supply issues

May have been the mains switch but I'd keep a careful eye on it. Enjoy your 47"!

My dad has permanently adopted the 50" NEC plasma I fixed. He was supposed to sell it, but he considers it an early birthday present

Is this a 1080p or 720p set?