18-09-2016, 10:00 PM
Poor focusing: A common fault with the 8500 and 8800 series was the resistor in the EHT rectifier tray going high value. Some timebase panels employ a BF256 FET as a source follower which serves as a buffer between the field timebase sawtooth forming capacitor and driver of the output stage.
In later timebase boards the FET was replaced by a BC147 transistor.
I notice that your set has the early production signals board. In 1975 a replacement board was introduced, the type PC651.
All in all these were good reliable sets, I had loads of them out on rental. Marketed as Ferguson, Marconi and Alba. The latter was the most popular with customers.
Geordie McBoyne.
In later timebase boards the FET was replaced by a BC147 transistor.
I notice that your set has the early production signals board. In 1975 a replacement board was introduced, the type PC651.
All in all these were good reliable sets, I had loads of them out on rental. Marketed as Ferguson, Marconi and Alba. The latter was the most popular with customers.
Geordie McBoyne.
