What have I done?!

[cglz]

Hi all,

First time post in this section but looking for a bit of advice as I think I'm in the dog house with the Mrs and I'm hoping that there's a resident TV repair man or expert within the great PH masses that can help me out.

Our TV (Philips 42PFL7603D about 4.5 years old) was making a popping noise from one of the speakers. Philips said that it'ss probably either a loose wire or faulty speaker.

In my wisdom I took the back off the TV checked all the wires and as they were ok I disconnected the affected speaker until the replacement arrives. I've altered the balance on the TV setup so all of the sound goes to the good side and jobs a goodun.

Execpt that it's not. The picture now has some very fine horizontal lines that flicker near the top of the screen and about 2/3 of the way down and the whole brightness of the screen flashes at times too, although this seems to be the top third and then the bottom at different times.

Now other than blowing a bit of dust off everything and disconnecting 2 wires that only served the speakers I didn't touch anything. So what have I done?

I have tried playing with the settings in the TV menu and the only thing that made a difference was that the problem got worse when I restored the factory settings. I have put the settings back as I had them before and this had lessened the flickering again but it's still there. On a screen with nothing moving and no sound, like the menu page there is very little if any flickering.

Apologies for the long winded post but it's not the easiest thing to describe!

Any help would be greatly appreciated but my gut feeling is that on this occasion I should have left it to the experts and it may cost me a new TV.

[TonyRPH]

It sounds as though you may have dislodged an earth somewhere.

There may have been a metal strip between the front and rear cabinet - or possibly even an earth wire.

It may even be that the speaker you have disconnected provides an earth path too.

[cglz]

Thanks for the reply Tony. However I'm not sure if there is an earth at all. The power supply is a twin cable (i.e. live and neutral, no earth). The back of the TV is one big piece of plastic with nothing except the speakers and some led's attached.

Would there still be an earth somewhere within the TV?

[OldSkoolRS]

Not strictly an earth, but a 'screen', which is the zero volts reference point for the various circuits. This is a bit like the way car electrics work, with the -ve of the battery connected to the body of the car (the case and chassis on your TV). If one or more of these is disconnected then the circuits will try to find an alternative path to the -ve and you could well get odd things happening. Hopefully it hasn't caused any permanent damage and all will be well once it's all reconnected.

[TonyRPH]

Yes ^^^ I should have really used the term 'shield' or 'screen' which in effect is a virtual earth or ground.

It's there to discharge any residual static* into the negative of the TV power supply.

• static generated by you walking across the carpet and touching the cabinet / the TV being dusted etc.

The symptoms you describe would suggest you have a static discharge leaking somewhere.

[cglz]

Thanks for the replies guys.

It appears to have sorted itself out at the moment so I'm leaving well alone.

Having said that my wife foudn a small piece of copper foil (about 1.5 inches by just under half an inch) on the floor when she was clearing the Christmas decorations up. I'm wondering if this was knocked off the back of the TV somewhere when I dusted it. I seem to recall there being 2 big flat connectors on the back, one on a PCB and another leading to the back of the screen. Presumably they had a function so this may be the cause of my problem?

Anyway, as said seems to be no problems at the moments so I won't touch it unless it rears it's ugly head again.

Thanks again for your help!