technika tv no power


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technika tv no power

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angellonewolf
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Jan 20, 2015, 10:07 PM

Post #1 of 23 (8808 views)
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technika tv no power	Can't Post

i have a technika 32 inch lcd 32-56 product number tw32x56btcug402 the problem is there is no power i have removed the back and found the main fuse blown on the powerboard and a burn mark coming from the small coil by the side of the fuse if i can find a way off adding a pic this would tell a hundred words i know a small amount in general electronics from the mark it looks like it has blown and on a auction site the replacement board for the tv is £14 inc delivery i am just thinking that i would like to confirm that i am right and a new power board will fix it before going ahead or going through the board and replacing the broken parts but as £14 for another board a few parts inc delivery will soon add up it does not look like a few blown caps but this is why i am posting here to get your info on it thanks for any help angel 

(This post was edited by angellonewolf on Jan 21, 2015, 3:27 PM)

jts1957
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Jan 21, 2015, 5:09 AM

Post #2 of 23 (8790 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

http://www.tv-forums.com/...i?post=157911#157911

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angellonewolf
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Jan 21, 2015, 3:42 PM

Post #3 of 23 (8774 views)
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Re: [jts1957] technika tv no power [In reply to]	Can't Post

i mucked around a fair bit and cant get it to work but if you copy and paste this in to an address bar you will get the pic

https://imageshack.com/i/p9Y8w5bej

 hope this is a clear picture and explains that i think i found the fault thanks for the help angel 

(This post was edited by angellonewolf on Jan 21, 2015, 3:43 PM)

jts1957
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Jan 21, 2015, 7:34 PM

Post #4 of 23 (8768 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

That's a simply coil or choke. Ebay pix is also a bit unclear.
If one PAIR of wire leads attach it to the board, just check across them for continuity (with Mains line cord disconnected - either at pcb or at wall outlet). If TWO Pairs of wire leads attach it to the board, each pair should have continuity.
If you like, you could also connect Mains and measure for DC volts across the largest electrolytic capacitor (the one laying on its side with bar code label). Should be well over a hundred volts DC.

Do they label the 3 white connectors with each pins voltage or function?

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angellonewolf
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Jan 22, 2015, 8:54 AM

Post #5 of 23 (8756 views)
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Re: [jts1957] technika tv no power [In reply to]	Can't Post

thanks jts

i have cheaked and there is 240 through to the power board

and up to the fuse as can be seen in the pic i have bypassed this with some 5amp wire in the hope it will come on and it was only the fuse blown but know they normally blow because there is a problem with a piece on the board

thats as far as i got

will try cheaking what you say and get back later

again thanks

ps do you think as can be seen from my pic its a blown choke that is the problem ?

angellonewolf
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Jan 22, 2015, 9:41 AM

Post #6 of 23 (8754 views)
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Re: [jts1957] technika tv no power [In reply to]	Can't Post

done some more work

more pics of the board with number marks

good pic of board
https://imageshack.com/i/hlWdnbu7j

pic of burn mark and where i think the problem is
https://imageshack.com/i/f0m2Thw6j

pic of back of board numbered
https://imageshack.com/i/p717muNej
number 1 is live/postive power will go from number 1 throught the fuse on the other side of the board to one side of the coil and got continuity through the coil to number 2 ok

number 3 is the netural goes up to the top of the 3 ok but has an open circuit throught the coil to number 4

this mean that the coil or choke has blown ?

jts1957
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Jan 22, 2015, 10:27 AM

Post #7 of 23 (8752 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

Yes, coil is blown. Since you like to put in jumpers, solder a jumper between number 3 to number 4.
You may get the house breaker to trip, the jumper to go to little tin balls, foil(s) to fry &/or parts to char and smoke .... or the set will work. Wink

Of course, you could measure resistances across some major part looking for a low reading FIRST. A Dead shorted reading across a diode is a bad thing.

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(This post was edited by jts1957 on Jan 22, 2015, 10:30 AM)

angellonewolf
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Jan 22, 2015, 7:32 PM

Post #8 of 23 (8746 views)
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Re: [jts1957] technika tv no power [In reply to]	Can't Post

yes thanks for that i will not be jumping the coil lol as even i assume its there for a reason and i only jumped the fuse with the same size fuse wire not a nail

what would be the aprox cost for a coil

and should i need to cheak any thing else eg poss could it have blown something else in the circuit as if it comes to to much i might be better replacing the board than just the coil ?

thanks for the replys angel

jts1957
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Jan 22, 2015, 9:08 PM

Post #9 of 23 (8742 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

Quote

Of course, you could measure resistances across some major part looking for a low reading FIRST. A Dead shorted reading across a diode is a bad thing.

IF HAS low resistance readings (that would be the thing to check further).

IF NO low resistance readings are encountered (this would include the pins of the 3 white connectors, with reference to ground, with them all plugged in), THEN try jumpering the coil.
At that point you'd have little to lose before replacing whole board.

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(This post was edited by jts1957 on Jan 22, 2015, 9:09 PM)

angellonewolf
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Jan 22, 2015, 10:04 PM

Post #10 of 23 (8738 views)
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Re: [jts1957] technika tv no power [In reply to]	Can't Post

another pic another story

https://imageshack.com/i/ip6ztG1sj

the only low resistance i can find is one in number 5 in pic is this another type of fuse 3.3

and low restance in number 6 in pic 1.2

i cant find any cross shorts from poss to neg or to ground around the board

and yes i have a rcd in the main board if you think i should be able to jump it

and yes i do it my own risk i know that lol

and feed back on the low Resistance i found

or shall i go a head with the jump

ps price if just the coil and fuse ?

again thanks for all the help

jts1957
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Jan 22, 2015, 10:42 PM

Post #11 of 23 (8731 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

5 = VDR = Normal reading

6 = Resistor = Normal reading

Coil can still be used (enamel scraped off burnt lead then either add a length of same gauge wire to extend or unwrap, by one turn, the too short lead. Either one will require you to remove the coil and reinstall after modification.

Can't see through tubing thats covering, so I can't determine exact type, but should be similar (in physical size) to: http://www.ebay.com/...;hash=item5ad4acc7fe

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angellonewolf
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Jan 23, 2015, 9:41 AM

Post #12 of 23 (8723 views)
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Re: [jts1957] technika tv no power [In reply to]	Can't Post

i must say what a great help you are especially the fast response thanks again

if i remove the coil that should not be a problem and remove 1 turn i assume solder a joint the wire together will i need to insulate as i wrap it through the coil ? or is the coil insulated from the wire ?

thanks angel

ps is it poss just to jump the coil to see if the unit works ? as a test ?

jts1957
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Jan 23, 2015, 11:18 AM

Post #13 of 23 (8721 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

Toroids can be wound using conventional plastic insulated wire or with enameled insulated wire. For an enamel insulated wire to be connected to the outside world it has to have the enamel insulation removed. IF yours currently does NOT have the space to accomplish scraping off of the enamel insulation (or the length for the freshly exposed wire to be reinserted back through your printed circuit board), pushing the too short wire back through the 'donut' of the core is a way to accommodate both.

Quote

Yes, coil is blown. Since you like to put in jumpers, solder a jumper between number 3 to number 4.

Quote

IF NO low resistance readings are encountered (this would include the pins of the 3 white connectors, with reference to ground, with them all plugged in), THEN try jumpering the coil.
At that point you'd have little to lose before replacing whole board.

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Location: Far, Far Away

angellonewolf
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Jan 23, 2015, 12:24 PM

Post #14 of 23 (8717 views)
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Re: [jts1957] technika tv no power [In reply to]	Can't Post

Sorry for the stupid questions

Can I just reduce the coil wrap on both sides of the coil unwind both the positive and neg sides by one wrap and scrap and resolder with out causing any problems or are they wrapped a certain amout of times for current or voltage reasons

Thanks again

jts1957
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Jan 23, 2015, 12:53 PM

Post #15 of 23 (8715 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

I've always just done the one side.

"Smaller chokes are used in switching power supplies to remove the higher-frequency switching transients from the output (and sometimes from feeding back into the mains input); these often have toroidal ferrite cores."

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angellonewolf
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Jan 23, 2015, 1:14 PM

Post #16 of 23 (8713 views)
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Re: [jts1957] technika tv no power [In reply to]	Can't Post

So I can just unwrap one turn scrap and resolder back on to the board ?

Leave temp the fuse wire to replace the fuse that has blown

Plug all back up as should be with power board and cheak the plug live nutrual and earth and see if there are any shorts across any lines inc ground if thats OK I should be OK to try it ?

Turning on using a long stick lol ( rolls around laughing)

Thanks again this is very interesting I have had a few interests over the years computers and more recently petrol mowers and strimmers but having fun with this and cost is not as I got a fair bit of things to do this with

jts1957
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Jan 23, 2015, 1:46 PM

Post #17 of 23 (8712 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

Yep.

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angellonewolf
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Jan 23, 2015, 2:05 PM

Post #18 of 23 (8709 views)
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Thanks for the helps again I'm a work today but will try to have a go later will post back asap to let you know that I am dead or the TV turned on

Thanks angel

angellonewolf
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Jan 25, 2015, 1:33 AM

Post #19 of 23 (8694 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

good news its alive

i done what you recommended and unwound the coil by one turn and it snaped while doing so so had to do 2 turns scraped and soldered

the fuse went to local maplins bought 10 5a slow blow fuses for £3.09
soldered some wire on each end and soldered in to place to replace the fuse

and up it came i have been using it for about an hour tonight for the 360 playing will do so for a few weeks as i have a place for it to go a friend has just got in to geting fit and needs a extra tv so will prob donate it to her

and keep my eye out for another to play with

thanks for all the help on this one hope if i get any more i can use your help again

thanks very much angel

ps have an extra pint for me next time you are out you deserve it

jts1957
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Jan 25, 2015, 2:11 AM

Post #20 of 23 (8693 views)
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Re: [angellonewolf] technika tv no power [In reply to]	Can't Post

Glad it worked.
Keep an eye on it for a couple of weeks - Don't leave it playing unattended.

A surge protector wouldn't hurt, and even then I'd suggest unplugging it during electrical storms. Wink

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angellonewolf
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Jan 25, 2015, 2:09 PM

Post #21 of 23 (8684 views)
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i will be using it on the 360 for a few weeks and power will be switched off on the power switch not left on standby for this time

again thanks for the help i did enjoy playing and did bring back memory's from my sparks training years ago we had to do a part one of electronics for it as i have said had a few hobbies in the last few years keeping my self useful and my mind going

and its a lot warmer working inside and its not as seasonal as mower and trimmers and i have been offered one or to bits but might have to take a brake as got the bedroom to do in the next few weeks and having a tv apart in on the kitchen table did not make the otherhalf very happy untill see seen it working

mack G™
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Jan 28, 2015, 8:54 PM

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mack G™
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Jan 28, 2015, 8:55 PM

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(This post was edited by mack G™ on Jan 28, 2015, 9:26 PM)

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