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LCD TV problem

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spike47

Member
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
 

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Nigel Goodwin

Super Moderator
Most Helpful Member
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

Member
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

Banned
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

Super Moderator
Most Helpful Member
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 :p

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

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

spike47

Member
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
 
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Hero999

Banned
IT could be internally arcing across the capacitor.
 

arunb

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

spike47

Member
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
 

spike47

Member
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
 

tytower

Banned
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.
 

spike47

Member
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?.
Hi

I have found the problem to be a short in the Switch mode transformer , I desoldered the cap , and the noise was still there although now very faint , so the short was puting a load on the cap ! .

thanks for your reply appreciate .

rgards

spike
 

shawnwilliams

New Member
I think you have problem in switch mode transformer because I also used the LCD TV but I don't have any these types of problem.
You have to check out the plugs and wires. After that once again you have to test your 19" Technika lcd TV.
 

spike47

Member
I think you have problem in switch mode transformer because I also used the LCD TV but I don't have any these types of problem.
You have to check out the plugs and wires. After that once again you have to test your 19" Technika lcd TV.
Hi

Thanks for your reply , Yes it is the switch mode transformer , I am trying to locate one , but up to now no luck .

cheers

spike
 
Last edited:

EDDIESMITH

New Member
Hi Spike
We too have this tv on the bench with the same problem - would you let us know how u get on sourcing parts etc -
are u able to modify ur picture highlighting components to be removed/replaced?

thanks to others for help in this one - it might save it from the dump
regards
Ed
 

spike47

Member
Hi Spike
We too have this tv on the bench with the same problem - would you let us know how u get on sourcing parts etc -
are u able to modify ur picture highlighting components to be removed/replaced?

thanks to others for help in this one - it might save it from the dump
regards
Ed
Hi

No luck at all , I can not find any reference to the switch mode transformer model number , there is simular transformers out there but I dont know the inputs outputs etc of this one , it is a shame because that seems to be the major fault with this model LCD tv , I was only doing this for a friend , and to be honest I have stopped looking , I have spent so much time on this , there is lots of people out there trying the same thing but I am afraid it is the skip , apart from the 19" lcd that is , sometimes it is only the shotty rectifiers the 2 at the back of the transforformer , but if you can here a clicking , then it is definetly the transformer , what seems to confuse people is that a small blue ceramic capacitor near the transformer sound like it is the culprit , but if you remove that you can still here a faint clicking( arcing) from the transformer .

hope you have look , if I do manage to locate something I will let you know .

cheers

spike47
 
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