Abstract: A vertical circuit board soldering apparatus for soldering printed circuit boards by immersing them in a molten solder bath. Air knives are employed to remove excess solder from boards leaving the bath. A displacement mechanism vertically dips the circuit boards. The mechanism comprises a parallelepiped frame that comprises two spaced apart parallel rails securing a sliding chassis therebetween. The chassis comprises three parallel spaced apart members. An upper member transversely extends between the rails while captivating a portion of each rail adjacent its ends. A parallel lower member depends from the upper member with an adjustable intermediate member therebetween. The intermediate member also transversely extends between the rails while captivating another portion of the rails. The intermediate member is coupled to the upper member by a screw jack that moves the intermediate member upwardly or downwardly to vary the distance therebetween to accommodate various board sizes.