View Single Post
Old 17th Mar 2021, 11:03 pm   #1
vintage_8bit
Heptode
 
Join Date: Feb 2013
Location: Rainham, Kent, UK.
Posts: 523
Default 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
Attached Thumbnails
Click image for larger version

Name:	S640.jpg
Views:	182
Size:	80.3 KB
ID:	229443   Click image for larger version

Name:	S640 mains Trans.jpg
Views:	192
Size:	56.8 KB
ID:	229444  

Last edited by vintage_8bit; 17th Mar 2021 at 11:12 pm. Reason: Post in wrong area?
vintage_8bit is offline