Museum of the Broadcast Television Camera

Marconi MkIII rack mounting power supply type BD630D rear view

Marconi MkIII rack mounting power supply type BD630D rear view

The rear view of the PSU. Top left is the main reservoir/smoothing capacitor bank, just below it is a solid state rectifier (germanium) replacing the 6 5R4 vacuum rectifiers. **

The brown object is the contractor for the mains input. The large wirewound resistor at the right side is in the HT return circuit and the small voltage developed across it is for the alignment coils. Between that and the main capacitors is the time delay relay that delays the application of HT until all the valves have warmed up.

 

** removing the 6 thermionic rectifiers saves 60W of heater power plus the anode dissipation.