How can I match a horizontal driver transformer.

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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.


Re: How can I match a horizontal driver transformer.


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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Re: How can I match a horizontal driver transformer.



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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.



Re: How can I match a horizontal driver transformer.


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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Re: How can I match a horizontal driver transformer.


finger to keyboard and composed:

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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
--
Please remove one 's' from my address when replying by email.

Re: How can I match a horizontal driver transformer.


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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Re: How can I match a horizontal driver transformer.


finger to keyboard and composed:

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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.

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- Franc Zabkar
--
Please remove one 's' from my address when replying by email.

Re: How can I match a horizontal driver transformer.


That will do me.
Great to have you on board,thanks again Frank.
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Franc Zabkar wrote:
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