Re: Dry joint on 28" Hitachi wide screen TV?

Jan 20, 2005 4 Replies
T


Failure to come on suggests PSU as a likely candidate, though not the >only one.


I thought it might be around that area but other things (like overvoltage to the HT) can cause TV's to shutdown can't it?



>But you need to be aware of the various dangers in TVs before poking
>about. Theres caps that store mains V, live lines on boards, 25kV EHT,
>with storage in the tube, and one or 2 HT lines as well for eg focus
>(maybe a few kV) etc. Plenty of ways to cook.

Hi and thanks for the reminder ;-)


I can remember watching an old-school TV engineer re-joining the broken turn on the mains dropper resistor with his fingers with the set still on .. ;-( (only 240 I know but that still tingles )


If this wasn't (potentially ) a (free) nice 28" TV I wouldn't go there out of choice ..


I have fixed a few swiched mode PSU's in my time but don't bother with PC ones any more (too cheap).


All the best ..



T i m


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A

Out 28" hitachi did exactly the same - it was rented so an engineer (!?) came out and knew exactly where to look, he just remade a couple of joints (I couldnt tell you where on the board though) and it has been find since - he said it was a common fault.

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T

Hmm, I re-soldered all the main joints today and now I have a *dead* telly ;-(

The problem is I may have 'firmed up' the intermittent fault?

I have spoken to an ex TV repair mate and he might pop in to point me in the right direction, or get one of his TV repair mates to sort it for me. ;-(

All the best ..

T i m

>
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B

oh :( do crosspost this lot to sci.electronics.repair.

NT

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B

overvoltage to the HT) can cause > TV's to shutdown can't it?

HT overvoltage would be a PSU fault. If you mean EHT overvoltage...

On second thoughts it might not be set up like that, I dont do tv repairs any more. SMPSUs can be a right pain now with their overzealous protection schemes, so youre right its not necessarily a psu fault. Just a question of starting where things are most likely. Thats the way when you cant divide and conquer, and with todays overprotected psus you often cant.

Its good you know the risks, i just never know whos going to read these posts on a public ng.

NT

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