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Old 7th Mar 2021, 3:09 pm   #1
generec
Diode
 
Join Date: Mar 2021
Location: Benfleet, Essex, UK.
Posts: 5
Default Need an Isolation Transformer for CTX-S (Philips 14CT2006)

I have this old Philips 14ct2006/05 television that uses the CTX-S chassis.

I’m planing to add a scart connector to it for video and rgb input.

I’m using a schematic from an old article to build a scart board.
This Tv uses a very similar chassis and the same TDA2540 and TDA3650 chips described in the article.

This unit has a live chassis and needs a isolation transformer installed. The article doesn’t go into specifics much but says a 120va toroidal should be adequate for sets like this.
I’ve looked around at some transformers but I’m not sure what type I need regarding primary and secondary values.

Can anyone help determine a specific transformer to use?


Also the only part of the scart schematic I don’t understand is the “AV time-constant” output.
The article mentions connecting it to “the line generator chips VCR select input” and “the line generator chips time-constant is changed by applying 12v to the selector pin” but doesn’t make any other specific mentions of this.

Any idea where the “AV TC” output of the circuit goes?


I’ve linked the full article here: Pages 20, 22, 23.
https://worldradiohistory.com/UK/Pra...on-1991-10.pdf
I can't link or post the full ctx-s service manual here and I'm not sure what parts would be most useful to help determine a compatible transformer, so I've just included a crop of the bridge rectifier for what its worth.
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