LG 50PQ6000 unstable 5v standby

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

On a side note I do need to get myself a little component kit togeather.

[tom66]

Re: LG 50PQ6000 unstable 5v standby

Pick up another TV with bad caps?

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

What and strip it?

[tom66]

Re: LG 50PQ6000 unstable 5v standby

No... fix it!!!

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

will have a look about.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

Thanks for your help guys Zener replaced and came to life.

[tom66]

Re: LG 50PQ6000 unstable 5v standby

Not a zener. A real diode. Glad you fixed it!

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

Well it's worked for 4 weeks with some light use and then got home from the staff party at work for the Mrs to moan at me saying that TV I Fixed is rubbish. Haven't had the back off again just yet but simulated symptoms as before with the diode. Broken again!

[tom66]

Re: LG 50PQ6000 unstable 5v standby

Yeah, looks like the 150V diode might not have been good enough, would need to source a 200V one, but seems damn near impossible!
You can try UF5402~UF5407 but they are only fast recovery... not schottky.

[ben7]

Re: LG 50PQ6000 unstable 5v standby

Yeah, looks like the 150V diode might not have been good enough, would need to source a 200V one, but seems damn near impossible!
You can try UF5402~UF5407 but they are only fast recovery... not schottky.

Hm, maybe it deserves a snubber circuit across the diode?

[tom66]

Re: LG 50PQ6000 unstable 5v standby

I think it already has one but it could be bulked up.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

Yeah, looks like the 150V diode might not have been good enough, would need to source a 200V one, but seems damn near impossible!
You can try UF5402~UF5407 but they are only fast recovery... not schottky.

Hi Tom

Well I thought I did well and got one of these (link below)

Would something else in the tv be pulling too much current, maybe on its way out and cause it to blow do you think?


http://www.chsinteractive.co.uk/elec...de-general.htm

[tom66]

Re: LG 50PQ6000 unstable 5v standby

Found a source, nice. That should last as long as the original did. Maybe three years or so. I think it's a design flaw for it to not use a proper heatsink. Clearly the part runs much too hot. When installing it, try maximising the lead length. Longer leads will lead to greater heat dissipation capability.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

Found a source, nice. That should last as long as the original did. Maybe three years or so. I think it's a design flaw for it to not use a proper heatsink. Clearly the part runs much too hot. When installing it, try maximising the lead length. Longer leads will lead to greater heat dissipation capability.

This is the component I found 4 weeks ago and replaced the original with. Fortunately I ordered 2.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

In not so sure about fitting the 2nd one unless I under stand a bit more why the first replacement blew.

[ben7]

Re: LG 50PQ6000 unstable 5v standby

In not so sure about fitting the 2nd one unless I under stand a bit more why the first replacement blew.

As tom said, it may be too much heat. There are diodes that you can buy which are meant for inverters, they are like 600v, 3A schottkies. I don't know if they have a lower forward voltage drop, but they DO come in better cases (TO-220 for example) which will dissipate the heat better.

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

[QUOTE=ben7;294390]As tom said, it may be too much heat. There are diodes that you can buy which are meant for inverters, they are like 600v, 3A schottkies. I don't know if they have a lower forward voltage drop, but they DO come in better cases (TO-220 for example)

So I need to find a better schottkie with simular characteristics?

[tom66]

Re: LG 50PQ6000 unstable 5v standby

You can't fit a TO-220 in that position though, as it's designed for a DO-201 which is an axial package, not designed for mounting to a heatsink. You are stuck with LG's poor design...

[ben7]

Re: LG 50PQ6000 unstable 5v standby

You can't fit a TO-220 in that position though, as it's designed for a DO-201 which is an axial package, not designed for mounting to a heatsink. You are stuck with LG's poor design...

Who says we can't mod it?

[Baileybum1234]

Re: LG 50PQ6000 unstable 5v standby

Who says we can't mod it?