Baird X47DTV power supply issues

[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

On same PSU or other PSU?

[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

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

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.

[gilly1984]

Re: Baird X47DTV power supply issues

Here is a pic of it tom.

[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

Shit. Will get some tomoz.

Cheers.

[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.

[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

not sure what stuff this is, got it off a mechanic who fixes electric milk floats.

couldn't use the cheap stuff from eBay, iron wasn't hot enough to melt it.

should I use this thread to ask about the poor sound quality and possible speaker upgrade.

[tom66]

Re: Baird X47DTV power supply issues

All LCD sound is poor, solution is to use a 5.1 system, you can get them pretty cheap as faulty.

[gilly1984]

Re: Baird X47DTV power supply issues

already have an AV amp but only like to use it for films, I'm probably just used to the Sony TV, that sounded nice.

first question the missus asked about this Baird is "what's wrong with the sound".

just have to get used to it then

hopefully case closed on this thing now .

thank you again pal.

[tom66]

Re: Baird X47DTV power supply issues

You could always sell it, and keep the Sony. Personally, that is what I would do.

[gilly1984]

Re: Baird X47DTV power supply issues

gave bro inlaw Sony for running me places when I buy TVs. no transport without him

woulndt sell it anyway with that ribbon bodge I did.

[gilly1984]

Re: Baird X47DTV power supply issues

Is this a 1080p or 720p set?

Plugged a Talk Talk YouView box into it and it said 1080p on the tv

But pc wont go to that resolution?

[tom66]

Re: Baird X47DTV power supply issues

No way you'll get 1080p over the cheap VGA electronics this TV no doubts uses. Must use DVI/HDMI for that. Heck even the Sammy in our living room only takes 1440x900 over VGA.

[gilly1984]

Re: Baird X47DTV power supply issues

Ah I see.

Need better AGP card then with hdmi out.

[tom66]

Re: Baird X47DTV power supply issues

Or DVI, which is compatible with HDMI. I use a PNY Nvidia 8400GS in the media PC. No fan on mine, so it's silent. Certainly not a great performer but you can play some half-decent games on low detail on it. Plus it helps with video playback.

[gilly1984]

Re: Baird X47DTV power supply issues

Just got myself another one of these tvs,

Keeps popping fuses this one, found a shorted mosfet on the main psu.

Obviously had problems in the past as the slave psu is different from the main one (Looks like an ebay chinese one)

There is also another mosfet that refuses to attract solder, the guy said it broke last time and he got someone to resolder it but obviously he had no idea what he was doing.

I am guessing the reason a mosfet blew is because this bad solder joint was floating.

The mosfet with the bad solder is not the one that blew though, the one that has shorted is the one closest to the main cap.

How can I get the solder to adhere to it?

PSU on left is original one from tv.