I decided to provide information that may be some help to someone. I recently purchased a Granville Phillips 260 ion gauge controller for very cheap from Ebay; when tested the filament would not engage. The instruction manual was down loaded from Ideal Vacuum :
Looking at FIG 4-3 Q8 drives the magnetic latching relay K3 when closed applies power to the filament. C2 stores energy so that when momentary switch S2 is engaged; C2 keeps Q* turned on long enough to allow time for the relay to latch. C2 in my case was weak; when it was replaced the filament circuit worked. The controller was tested with my diffusion pump system more or less agreeing with my old CVC controller.
