02-10-2020, 09:08 PM
(This post was last modified: 02-10-2020, 09:12 PM by Geordie McBoyne.)
Hi Trevor,
here's another tube protection circuit. The White-Ibbotson Mark 1 and 2 projection receivers employ a single EB91 as the fail safe protection device.
In this circuit it would appear the waveform on the line scanning coils provides after rectification by the right side section of V14 the positive voltage supply for the brightness control VR9.
In the event of frame timebase failure the left side section of V14 provides the protection. This part of the circuit needs further study as to ascertain how it works in the brightness control.
Negative going video supplied to the cathode of the CRT.
Geordie McBoyne.
here's another tube protection circuit. The White-Ibbotson Mark 1 and 2 projection receivers employ a single EB91 as the fail safe protection device.
In this circuit it would appear the waveform on the line scanning coils provides after rectification by the right side section of V14 the positive voltage supply for the brightness control VR9.
In the event of frame timebase failure the left side section of V14 provides the protection. This part of the circuit needs further study as to ascertain how it works in the brightness control.
Negative going video supplied to the cathode of the CRT.
Geordie McBoyne.
