20-07-2023, 10:04 AM
(This post was last modified: 20-07-2023, 10:06 AM by Geordie McBoyne.)
Yesterday my attention was drawn to the frame timebase, an attempt to increase the picture height. A marked improvement by replacing the scan coil coupling capacitor, it's C46 in the Ekco circuit diagram. The faulty component was a post-war replacement. The 8 + 8uF capacitor on the same sub-panel is connected between the cathode and screen grid of the PEN45 frame OP valve, another post-war replacement part.
The value of the cathode resistor is critical, the original value was 160ohms.
But there is only just enough vertical scanning and just enough is just not good enough. Plenty picture width adjustment.
Geordie McBoyne.
The value of the cathode resistor is critical, the original value was 160ohms.
But there is only just enough vertical scanning and just enough is just not good enough. Plenty picture width adjustment.
Geordie McBoyne.