How can I match a horizontal driver transformer.

I have Digitor 12 volt TV Model G7200 year 1993 from Dick Smith Electronics for which the H.D.Transformer is no longer available from spare parts. (Checked with DSE). I am thinking what specs to look for if I was to find a spare part in my parts box. Would this be possible at all? It drives the HOT which is a BU407 and the chip on the board is an LA7680 where pin 27 supplies the signal. Any expertize here will be welcome. Thks A.T.

Reply to
alitonto
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Hi!

It could be hard to find a replacement for your transformer since the tv set is fairly old. If you like to find a replacement just by looking at which hot and horzontal driver chip you got you are on the wrong way. Best thing you can do is to check at any local tv service and ask for an replacement, if there isn't you will most probably not find one. By the way, are you sure that you got an faulty ht-transformer? Sorry but not much I can come up with.

Good luck A.T

Bjorn

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Reply to
Rifleman

Your best bet would probably be to wind one yourself on a core from a scrapped SMPS transformer. Heck you could dismantle the original and rewind it if you wanted, there's not very many turns on them, but you need to be positive it's defective first! They can be difficult to take apart, you have to soak them in an appropriate thinner/stripper to dissolve the glue first.

Reply to
James Sweet

Thanks for comments fellows; I do not have that all H.D.transformer anymore. I have obtained the schems from DSE and maybe something on these can give clues as to what one can do to find similar part; If I approach a repair shop for a similar part, I wonder how he would go about matching it. Anymore ideas anyone? thanks Ali

James Sweet wrote:

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Reply to
alitonto

On 15 May 2005 06:15:10 -0700, "alitonto" put finger to keyboard and composed:

Try adapting a transformer from a current model 12V TV. I would imagine they would be mechanically different but electrically similar (same B+, same frequency, similar output).

- Franc Zabkar

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Reply to
Franc Zabkar

Hello Frank, That's the direction I was thinking but wasn't sure if anything in particular needed to be observed. For example the schematics I obtained from DSE, thnks for your previous reply, indicate that the volts to the base of the HOT needs to be 0.34; therefore would I be correct in thinking that the existing circuit board will produce that if I select a close enough match for the driver transformer? Cheers A.T.

Franc Zabkar wrote:

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Reply to
alitonto

On 16 May 2005 05:20:33 -0700, "alitonto" put finger to keyboard and composed:

AFAICS, any 12V HDT that is designed to drive an NPN transistor should be suitable. That's just about all of them. One caveat may be that some HOTs have a lower hfe than others, which would mean they would require more base current. A symptom of low drive would be a hot HOT. Just to be safe, I'd run the set for a minute or so and then check the HOT temperature.

- Franc Zabkar

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Reply to
Franc Zabkar

That will do me. Great to have you on board,thanks again Frank.

Franc Zabkar wrote:

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Reply to
alitonto

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