Eddystone S640. Mains primary open circuit.
Good evening.
Just starting work on this receiver. I have noticed the 200 to 240 tap on the mains primary is open circuit. A previous owner has just soldered a dropper resistor across the winding. I have removed this mod.
Looking at the output transformer I'm guessing the metal surround is pitch filled? If not I will drill out the top rivets and see if I can do anything with the open circuit. If not, its a rewind, replacement or perhaps use the 110V tap and a 240 to 110 step down transformer.
So does anyone know how the transformer is built up please?.
With just the rectifier and output valve fitted I slowly powered using the variac to 200V, with the 200V tap selected. The H.T. measured 250V and I had 39mA through the output valve and no hum, so a good result here.
I will now be looking at all the electrolytics and paper caps. I see the audio coupling cap to the output valve is mica. Colin
Last edited by vintage_8bit; 17th Mar 2021 at 11:12 pm.
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