UK Vintage Radio Repair and Restoration Discussion Forum - View Single Post

frsimen · 5th Oct 2022, 7:38 pm

Hello and welcome to the forum.

The best thing to start with is to check that the +110V, +20V and -20V supplies are correct. Be aware that the -20V supply tracks +20V supply, so a fault on the +20V will affect the -20V output too.

One further test is to see whether any of the shift controls can move the spot when adjusted.

Be very careful when working on this oscilloscope, the mains derived EHT can kill, so keep well clear of the high voltage areas.

Paula

5th Oct 2022, 7:38 pm	#2
frsimen Heptode Join Date: Jan 2011 Location: Croydon, London, UK. Posts: 773	Re: Gradual failure of Scopex 4D 25 Hello and welcome to the forum. The best thing to start with is to check that the +110V, +20V and -20V supplies are correct. Be aware that the -20V supply tracks +20V supply, so a fault on the +20V will affect the -20V output too. One further test is to see whether any of the shift controls can move the spot when adjusted. Be very careful when working on this oscilloscope, the mains derived EHT can kill, so keep well clear of the high voltage areas. Paula