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1100 man · 11th Jan 2018, 12:39 am

Hi,
TV's from the mid '50's to the mid '60's mostly have what I would consider a 'conventional' LOPT. That is an auto-transformer design with two bobbins mounted on each limb of a ferrite core comprising two 'c' shaped pieces held together by long brass bolts. One bobbin is the EHT winding and the other bobbin is all the rest of the windings.
Most of the TV's I've ended up with seem to be of this type.
My question is, how are the two halves of the ferrite core joined together?
The transformer pictured below is from a Marconiphone VT161 17" tv from 1959. The EHT winding is arcing to it's former and sending up a plume of smoke!
I have removed the connection board and the through bolts but the two halves of the core don't want to part even with moderate force. Are they glued together?
I've recently had exactly the same issue with the LOPT from my Pilot which I have been re- insulating. Again, the core did not want to part even when it was quite hot.
I would be very interested to know how they are constructed and how to get them to bits!
The third picture is the Pilot LOPT just to illustrate the type of construction.
Many thanks
Nick

11th Jan 2018, 12:39 am	#1
1100 man Octode Join Date: Apr 2016 Location: Ventnor, Isle of Wight, & Great Dunmow, Essex, UK. Posts: 1,377	Dismantling LOPT's Hi, TV's from the mid '50's to the mid '60's mostly have what I would consider a 'conventional' LOPT. That is an auto-transformer design with two bobbins mounted on each limb of a ferrite core comprising two 'c' shaped pieces held together by long brass bolts. One bobbin is the EHT winding and the other bobbin is all the rest of the windings. Most of the TV's I've ended up with seem to be of this type. My question is, how are the two halves of the ferrite core joined together? The transformer pictured below is from a Marconiphone VT161 17" tv from 1959. The EHT winding is arcing to it's former and sending up a plume of smoke! I have removed the connection board and the through bolts but the two halves of the core don't want to part even with moderate force. Are they glued together? I've recently had exactly the same issue with the LOPT from my Pilot which I have been re- insulating. Again, the core did not want to part even when it was quite hot. I would be very interested to know how they are constructed and how to get them to bits! The third picture is the Pilot LOPT just to illustrate the type of construction. Many thanks Nick Attached Thumbnails