Bending V Low

Error: inhibit, Bending V is below the lower limit

Check bending current. If none, check power supply (fuse).

Check if bending V is gantry-angle dependent. If so: The bending coils are sideways kept in place by means of small V-shaped metal spreaders. These spreaders (there are two of them!) hold the coils apart by pressing against the insulation material of the coils.

When the isolation of the coils is damaged (influence of high radiation flux) it is possible that a part of the bending coil is directly short circuited to earth! The bending current is servo-ed and kept at the correct value but because a part of the coil is shorted, bending V is considerably lower.

Take off the head and primary collimator, locate the spreaders and put some 'shrinking tubing' over it!

The first, and most comfortably located spreader is directly visible on the target side of the flight tube: easy job, but the second is hidden somewhere deep inside near the back of the flight tube: with the aid of a long pair of tweezers and a lot of luck it is possible to apply the isolation to the spreader.

Once done, your problem has been solved for at least 3-4 years.

It is good practice to routinely check the insulation of the spreaders every time the head is off for some reason: saves a lot of time.