Daewoo TV (Philips tube) 250v side fried - any help on identifying parts?

(please note I'm not an electronics expert so please go easy on me!)

Daewoo TV model DTY-28W5GB, 18 months old. Nice easy circuit board to pull out.

What happened was that I turned it on, and there was a crack, and it was dead. I took the lid off and saw a blown fuse in the 250v part.

Found the correct fuse from Maplin, put it back in, 1 second after turning on, CRACK! Fuse had exploded, and a small blue capacitor had melted down and blown itself off the board, and apart.

There are other capacitors on the "low" side of the board looking exactly the same as what this one should have looked like, and they have (I think it says 8 or could be R+), then 471k below this then 1Kv below that.

Nearby, there is a transistor package thing with 6(?) legs called an STR F6653 SK4714 and a friend says it's often them that go too, although physically it looks fine.

I've looked in the Maplin catalogue and can't find anything similar - am I doomed from the start with stuff like this? It's just that repairs are so costly these days, it would be cheaper to scrap it, and that's just more toxic landfill, so I'd rather try it myself.

I suppose and alternative would be a whole replacement circuit board - can't see Daewoo doing that though for an end user. Or maybe?

Reply to
digitaltoast
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you have a dead short near the mains input. thankfully you can narrow this down quite easily as there aren't that many components. first disconnect the degauss cables that go round the tube from the pcb. replace the fuse with one of the same rating and wire the tv to the mains in series with a 100watt bulb, and power it up. the bulb will limit the current in the event of a short still being present.- if it lights up very brightly then unplug and desolder the STR regulator. repeat the above..... chances are there are some rectifier diodes shorted in the power supply. you'll just have to measure things right near the mains side.

-B

Reply to
b

I think repairing the exploded capacitor might be first :)

Isn't that little filament not going to handle a high amp surge very well?

Hmm, I'm starting to wonder if it isn't time to upgrate to an LCD - or just stop watching TV! I'll give it a go- thanks for the help.

Reply to
digitaltoast

If its marked on the board as C806 its value will most likely be 1000PF/1KV.

Reply to
Ivan

Of course it will, you can connect it straight across the mains, which as far as the bulb is concerned, can supply infinite current. The filament has a positive resistance coefficient and is self limiting, that's the reason for putting it in series.

Reply to
James Sweet

Oh yeah. See..this is why I'm not an engineer!

Thanks to Ivan for his suggestion too. Will try that tomorrow.

Reply to
digitaltoast

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