Ceramic Disc Capacitor Value?

[George]

Its probably been going for a while and every time he's pressed the on button it has taken more punishment from switch on and finally given up the ghost as the fuse keeps blowing now?

[George]

Have you ever tried looking for dodgy component in a TV in situ? let me tell you if your head touches the CRT PCB whilst trying to keep the Loupe in the eye socket and at the same time browsing over the chassis, it'll wake you up and make you have a jig around the room. ;-)

[George]

There ya go MrBarnes...not that expensive :-) and a monitor can be gotton off FREECYCLE

[Andy Wade]

If you have problems seeing something the size of the capacitor in question how do you get on with the 0402 and 0603 size SMDs?

[Harry Bloomfield]

zeros by 2 (divide by 100).

From what I can see... That ceramic is not leaking or even by the looks of it faulty. To me it looks as if some metal may have fallen across the terminals of the cap and perhaps that the PCB tracks have suffered some flash over. I'm a little puzzled by the pale green deposits, it looks like copper sulphate.

Ceramic when they go, usually have some more obvious signs. The case will be blackened and split due to heat.

A repair would involve drilling through the PCB to clear all the blackened material, then installing a new ceramic across what ever is left of the original tracks.

[George]

Try to avoid Surface Mount Devices MrHall ;-)

No the camera can go real close,the problem stems to getting a reading so close even with my reading specs on as the eyes tend to squint and become blurred.

I cannot read the real small print on some everyday items or paperwork for instance on medicine lables or containers.

[Andy Wade]

Or it may be that some other fault has resulted in full mains or rectified mains voltage appearing across this capacitor which, being rated at perhaps 50 V DC, has responded by blowing-up. Collateral damage like this is by no means uncommon with SMPS faults.

[Dave Liquorice]

I'd put money on something else, looking at the cap wires, the burnt board, coloured deposit and general sticky yuk of the board particulary top right corner. I'd say some liquid has got in at some point and caused a flash over between the pins of that C.

It appears it may have worked for a while but now the fuse blows at switch on. Suspect a knackered SMPSU, so probably require a new pair of driver transistors, the control IC and other sundry bits to get back working. If it takes more than a morning in total to repair it's not economic, there are other reasons for fixing things besides money though.

Yep down to the left of the big C below the burnt one are the words "LIVE PART ..." The diodes look to be 1N4006, rated at 800V. Bite with a capital B.

[geoff]

In message , George writes

is that a burn I see between the legs ?

Liquid has dripped on it or something

[Alan]

In message , George wrote

The damage looks like burning caused by a liquid being dripped onto the board. You may have to drill out the carbonised area of the board or else the carbon will be conductive.

Consider also the voltage rating of the capacitor - it could be rated at

250V or 400V (maybe higher). It's NOT the 50V( ish) type ceramic plate capacitor.

Suppliers CPC, Maplin, RS

rswww.com

[Bob Eager]

I use four different loupes, but need to wear my glasses too. So I also have one of these; four different lenses and some illumination too:

the depth problem is still a bugger!

[George]

neck to look at components in that area or places where there is an obstruction. ;-)

[Bob Eager]

building boards - and the long focus one works OK for the innards of Pcs.

[George]

Perfect,no damage to the underside...weird

[Harry Bloomfield]

George explained :

Flash over between the legs of the capacitor then. You need to at least clean the carbonised layer off the upper surface of the PCB as a first step.

[Mike Barnes]

Well, yes, you can if you're not careful. :-)

[The Natural Philosopher]

The worrying possibility is a short between primary and secondary on the mains transformer.

[George]

No chance of just faulty cap then? ;-)

[The Natural Philosopher]

If it is a switched mode power supply, then like as not a whole bunch of stuff has invisibly failed somewhat before the cap gave up the ghost. Up to and including everything on the hot side of the ferrite transformer, and the transformer itself.

Try all the rectifiers, the mains rated capacitor and the power FET..and probably any chip associated with it as well.

Things were simpler before SMPS..fixing valve stuff was almost all about 'replacing valves till it worked'

The rot set in with transformerless semiconductor power amps. Ther you simply replaced all the actives, tested them, and put the still functioning bits back into the spares box.

Then came SMPS and chips which you couldn't buy easily..and then surface mount. That you couldn't unsolder easily anyway..

[George]

If you need SMD components? try this place...

I won't fix SMD stuff as you have stated, not easy to desolder the components without the relative soldering iron tips but even when you have these the components are very compacted together on the pcb its very hard not to touch other components in the vicinity.

I have a 19" widescreen LCD monitor Id like to fix as when it was working the picture was crisp and full of life in terms of richness in colour and it truly was a exceptional picture. Alas I cant seem to fathom out where the problem lies,its stuck in the on mode as per the green led but is completely dead no back light and no sign of screen life which you can normally get a very faint image if you suspect the backlight is at fault. :-(