LONGINES 6512 ULTRA-QUARTZ 1970
The Longines "Ultra-Quartz" was available in two versions in steel or goldplate. Both use the 6512 movement but the date disc has a different print. The one pictured here is the rather classic model in comparison to the bigger style case with cool super-raised 3D hour indexes. It is worth to mention that the case and bezel (in both versions) are mounted together with two totally akward hinged pins. If these are missing it doesn't pay to make them from scratch as this would take hours. Instead get yourself some superthick springloaded bracelet pins and apply them properly - slight modifications might be needed.
As described in the earlier section you might expect an Ultra-Quartz to be extremely precise. After all these years some adjustments might however be required and basicly there are a few hints: 1) There is no trimmer to adjust the quartz unlike the Beta21 (both electronic modules pictured right for comparison) so instead there are four small screws on top of the quartz bar. Each screw is responsible for activating a corresponding resistor (no idea of values) so a wide range or troubleshooting is required to adjust the module perfectly - use 1 or all 4 screws (find generic screws first if none are present). The same screw-adjustment concept was used in the 1972 Bulova Accuquartz.
2) Proper timekeeping might be influenced by correct indexing and adjustment of the pawl and index fingers. This is maintained by turning a screw at the pawl finger and increasing or decreasing the pressure of the pawl finger jewel on the index wheel - allowing for proper indexing according to Accutron methods. Manual modifications of these fingers might be needed on an old watch. 3) The counter-weight on the torsion bar can also be modified for optimal vibrations (timekeeping). 4) The index wheel that is activated by the motor module transmits the torque through a spiral worm pinion onto the gear train. The motor module base plate can be slightly moved and adjusted by means of two screws allowing the finger jewels to achieve optimal contact with the index wheel.
Other hints: # note the copper "tip bearing" of the sweep seconds pinion that is mounted on the gear train plate (next to the serial number) - this akward pin might be loose or even missing and cause malfunctions. # If the watch hums but does not work or keep time please check and apply proper friction on the cannon pinion. # If the date does not advance please disassemble the date assembly and make sure that the hooked finger that should move the disc is properly fastened and has enough pressure from a corresponding spring. Btw. if I'm not mistaken at least 2 gears from the date assembly are identical with the Beta21 :) # The movement has a hacking (stop) function when you pull out the crown for time setting - if the movement doesn't stop you should either adjust or replace the small gilded plate fixed with a gilded screw as it should be touching the stem hole collar when the crown is pulled out and thus disconnecting the circuit.
Keywords: longines ultra-quartz, 6512
Market value: 250-1500$ (condition, box)