Ekco TC 209 - repairing Perspex LOPTx - UK Vintage Radio Repair and Restoration Discussion Forum

retroaudio · 18th Sep 2007, 10:03 pm

I have the above set which until recently was working ok. The VHF radio was also working. It seems to have developed a problem which Iam told is relatively common. Trevor (murphy v310) has kindly given me some advice on it to date. The overwind on the lopt is arcing and overheating. I am told this happens as these sets age and is caused by the plastic former which the lopt is built on. Is there a straight forward way round this problem in terms of dismantling the assembly and remounting the components on a more suitable material ?. I would appreciate advice from other forum members

Alex

Heatercathodeshort · 19th Sep 2007, 7:31 am

Hello Alex,
I used to make these transformers as a young lad. The Ekco series are very easy to take apart; only a few connections need to be unsoldered and a 4ba screw. I presume it's the case that is burning and not the actual overwind. A sweet sickly smell usually goes along with the arcing case.
You will need to cut three pieces of Paxolin sheet to form the sides and top.
Drill holes to allow threaded rod to pass through and secure the core and windings between the new sides. The third piece, smaller for the top can be drilled to takr the solder tags for the U25.

You may have a later transformer using the U26 and if this is the case only one tag will be required for the anode cap.

The transformer is easily fitted to the chassis with the original 4ba screw. Take care when unsoldering the overwind. It's a fine lead. The windings on these transformers very rarely, if ever, fail. Its' just the perspex case that bites the dust; you could, of course, use Perspex if you had some to hand.
We would all be in a better place by the time it failed again... Regards, John.

Heatercathodeshort · 20th Sep 2007, 8:50 am

Hello again,
As a young lad I used to make the whole Ekco range line output transformers from the T221 series right up to the last of the Perspex housed types around the T334.
At the time I worked at D and B Television at Wimbledon. Adverts in the PT's of the time list some of my work.

I used to wind what was known as the 'underwinds' and then with the aid of a 'Douglas' wavewinder, the 'overwinds'. Mullard Ferrox cores were used and a new Paxolin case cut from large sheets with the aid of a lethal band saw.........
The early 'round bridge' shaped Ekco transformers never suffered from this problem but all models from the T221 did. They must have changed the formula for the Perspex housings.
Ekco had a very early and well respected plastics division that survived long after the collapse of the company in 1961.

The attached sketch from memory, by the way, is the very rough make up that proved very satisfactory. We used all new parts at the time but suggest you salvage the corona cups from the original transformer. Take care when removing the core and winding assembly. Don't snap the wires off the bobbin......Hope this gives you some ideas and of course it can be modified to what materials you may have. Any high quality insulating sheet will suffice.

Regards, John.

18th Sep 2007, 10:03 pm	#1
retroaudio Pentode Join Date: Mar 2005 Location: Cairneyhill, Fife, UK. Posts: 135	Ekco TC 209 - repairing Perspex LOPTx I have the above set which until recently was working ok. The VHF radio was also working. It seems to have developed a problem which Iam told is relatively common. Trevor (murphy v310) has kindly given me some advice on it to date. The overwind on the lopt is arcing and overheating. I am told this happens as these sets age and is caused by the plastic former which the lopt is built on. Is there a straight forward way round this problem in terms of dismantling the assembly and remounting the components on a more suitable material ?. I would appreciate advice from other forum members Alex

19th Sep 2007, 7:31 am	#2
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Ekco Tc 209 Hello Alex, I used to make these transformers as a young lad. The Ekco series are very easy to take apart; only a few connections need to be unsoldered and a 4ba screw. I presume it's the case that is burning and not the actual overwind. A sweet sickly smell usually goes along with the arcing case. You will need to cut three pieces of Paxolin sheet to form the sides and top. Drill holes to allow threaded rod to pass through and secure the core and windings between the new sides. The third piece, smaller for the top can be drilled to takr the solder tags for the U25. You may have a later transformer using the U26 and if this is the case only one tag will be required for the anode cap. The transformer is easily fitted to the chassis with the original 4ba screw. Take care when unsoldering the overwind. It's a fine lead. The windings on these transformers very rarely, if ever, fail. Its' just the perspex case that bites the dust; you could, of course, use Perspex if you had some to hand. We would all be in a better place by the time it failed again... Regards, John.

20th Sep 2007, 8:50 am	#3
Heatercathodeshort Dekatron Join Date: Jun 2005 Location: Warnham, West Sussex. 10 miles south of DORKING. Posts: 9,147	Re: Ekco Tc 209 Hello again, As a young lad I used to make the whole Ekco range line output transformers from the T221 series right up to the last of the Perspex housed types around the T334. At the time I worked at D and B Television at Wimbledon. Adverts in the PT's of the time list some of my work. I used to wind what was known as the 'underwinds' and then with the aid of a 'Douglas' wavewinder, the 'overwinds'. Mullard Ferrox cores were used and a new Paxolin case cut from large sheets with the aid of a lethal band saw......... The early 'round bridge' shaped Ekco transformers never suffered from this problem but all models from the T221 did. They must have changed the formula for the Perspex housings. Ekco had a very early and well respected plastics division that survived long after the collapse of the company in 1961. The attached sketch from memory, by the way, is the very rough make up that proved very satisfactory. We used all new parts at the time but suggest you salvage the corona cups from the original transformer. Take care when removing the core and winding assembly. Don't snap the wires off the bobbin......Hope this gives you some ideas and of course it can be modified to what materials you may have. Any high quality insulating sheet will suffice. Regards, John. Attached Thumbnails