LCD TV problem

**spike47** · 14th August 2009 03:59 PM

Hi

I have a problem with a 19" Technika lcd tv , when it is swiched on all that happens is the red standby light is going on and of , and a small ceramic capacitor is clicking away , I have a sort of schematic and photo of the area of the pcb in question , I have removed one of the 2 shottky rectifiers for testing and It showed to be faulty , I have ordered a new one , but when I switch on the board the small cap is still clicking away , could this be a fault with the cap , ( 103 1kv ) I am not sure how to test it and if it has to be removed to test .

any help on this will be highly appreciated.

spike

**Nigel Goodwin** · 14th August 2009 04:35 PM

I would say that almost certainly it's not the capacitor ticking, but the transformer next to it.

Those little blue capacitors do commonly fail, but there are pretty well always signs of it, blown completely to pieces, cracked in half, or an obvious burnt spot on it.

**spike47** · 14th August 2009 04:53 PM

HI

thanks for your reply , I must admit it is difficult to find exactly where the ticking is coming from , but I have touched it with a plastic stick and the noise changes each time I touch it ! .

regrds

spike

**Hero999** · 14th August 2009 04:58 PM

Originally Posted by Nigel Goodwin

Those little blue capacitors do commonly fail.

It depends on the rating of those little blue capacitors; if they're Y rated, then they should never fail.

**Nigel Goodwin** · 14th August 2009 06:28 PM

Originally Posted by Hero999

It depends on the rating of those little blue capacitors; if they're Y rated, then they should never fail.

You're rather missing the point, they aren't Y rated because they aren't used on the mains, nor are they suppression components - so Y rating wouldn't be relevent. It's also rather hopeful, that Y rated capacitors never fail

They are high voltage, high frequency, used for tuning or damping spikes across a transformer - and VERY commonly fail, but if you look at the small size and high voltage rating, it's not surprising.

**Hero999** · 14th August 2009 07:15 PM

Yes you're right, they're in completely the wrong place to be Y rated capacitors.

**spike47** · 14th August 2009 07:43 PM

Originally Posted by Nigel Goodwin

I would say that almost certainly it's not the capacitor ticking, but the transformer next to it.

Those little blue capacitors do commonly fail, but there are pretty well always signs of it, blown completely to pieces, cracked in half, or an obvious burnt spot on it.

HI again

I have had another person to see where the clicking is coming from , and it is definatly the blue cap 103 1KV

cheers

spike

**Hero999** · 14th August 2009 08:35 PM

IT could be internally arcing across the capacitor.

**Nigel Goodwin** · 14th August 2009 09:10 PM

Originally Posted by spike47

HI again

I have had another person to see where the clicking is coming from , and it is definatly the blue cap 103 1KV

They are cheap enough, so change it - but I'm pretty sure it won't make any difference if you can't see any damage.

**arunb** · 15th August 2009 08:43 AM

the blue component could be a VDR (voltage dependant resistors), these are rated for voltages and generally are the first to fail...

**spike47** · 15th August 2009 09:43 AM

Originally Posted by Nigel Goodwin

They are cheap enough, so change it - but I'm pretty sure it won't make any difference if you can't see any damage.

Hi

Thanks guys for all your help , The problem is that I am having a problem locating this cap on the web unless offcourse I buy them in qty , I have asked a couple of local tv repair shops if they have one but to no avail , ( one of them I know so he did have look ).

cheers

spike

**Nigel Goodwin** · 15th August 2009 09:56 AM

As you're close, check CHS at Pocklington.

CHS - replacement remote controls, instruction manuals, audio & video accessories, electronic components & spare parts

Exact link, but out of stock.

10NF 2000V Ceramic Capacitors (RM=7.5mm)

**spike47** · 15th August 2009 10:31 AM

Hi

cheers for that link , that site never came up when I googled for the cap , I should of put North Yorkshire as my location , I have changed it now .

anyway thank you very much for your time and patience ; I am inclined to think that you are going to be right that changing it will not solve the problem , I am thinking it could be a short in the transformer and that is maybe why the cap is clicking , not sure about that theory though .I dont know why the red light on the other side of the board is flashing the same sequence as the cap is clicking .

regards

spike

**Nigel Goodwin** · 15th August 2009 11:38 AM

The PSU is probably 'tripping', the clicking noise from the transformer is as it stops and starts - do you have a scope to check it with?.

**tytower** · 16th August 2009 09:56 AM

Just a practical tip .Noise can often be pin-pointed by a plastic straw stuck in the ear and pointed at the suspect device. A plastic tube of any kind in fact.

For cars and other non electrical use a long large screwdriver or stick with one end in the ear

Now I do mean layed against the ear of course. It might look odd with it stuck there.

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