(c) 2006 STE UK Ltd

For STE Van de Graaff Generator (280mm dome, blue tube, grey base).

This instruction covers belt changing and tensioning, cleaning and adjustment to get best spark. Carry out the stages as required.

INITIAL EXAMINATION

1)     Make sure the unit is switched off and mains lead unplugged

2)     Remove the upper roller by unscrewing the wing nuts on the roller support pillars. Take care not to lose the washers, and place it close to hand for replacement.

3)     Take this opportunity to clean both the roller and upper comb or collector plate. Do this using alcohol or meths on a rag.

4)     Unscrew the retaining screws from the base (2 on the top of the base, and 2 on each end of the front and back).

5)     Lift the upper part of the base off. It is still attached to the ground cable.

6)     There is a long green and yellow ground cable inside which should remain permanently attached. It is made this length to allow this procedure to be carried out without detaching it.

7)     Remove any debris from within the base and again take this opportunity to clean the lower roller and contact face of the lower comb or collector plate. This is done as with the upper roller and collector plate by using a rag with alcohol or meths. The lower comb or collector plate can be moved in an arc around the retaining nut. Give the contact edge a good clean. If not changing the belt you must still ensure that the top and bottom collector plates are in light contact with the belt.  

BELT CHANGING

8)     Remove the old belt and fit the new belt over the lower roller. Manoeuvre it though the hole in the base and up through the pillar supporting the dome, then hook it over one of the upper roller supports.

9) Take the upper roller and feed it through the belt, making sure there are no twists in the belt and refit the roller into the support pillars. Tighten the wing nuts slightly ready for final adjustment.

10) With some tension on the belt now (do not over tension it as this will reduce its life expectancy) look at the bottom collector plate. This should be just touching the belt. Friction is important to obtain a good performance.

RE-ASSEMBLY 

11) Check the ground connection is still sound.

12) Position the upper part of the base over the lower and re-fit the screws.

ELECTRICAL SAFETY

13) The following electrical safety check should be carried out: Check the fuse rating of the Van de Graaff (Located in the female part of the mains connection on the rear of the unit). Ensure it is a correctly rated 500mA ‘slow blow’ fuse (STE 14800). Check that the mains cable is in good condition, check the fuse rating in the cable is 3 Amp and the plug is fitted correctly if not a pre-moulded model. Test the mains cable in accordance with current electrical safety regulations and LEA guidelines. Carry out a Portable Appliance Test in accordance with current electrical regulations and LEA Guidelines.

14) Make sure the unit is switched to the ‘Off’ position and then plug into the mains.

15) Take a 4mm lead and connect one end into the functional ground socket on the front of the base of the unit and on the other end connect to a Crocodile Clip, then clip the Crocodile Clip to the Lower part of the Dome.  This allows you to run the unit without the build up of charge 

BELT ADJUSTMENT AND SPARK OPTIMISATION

N.B. Do not run the Van De Graaff Generator close to electrical or electronic appliances which may be affected by the very high electric field generated.

16) The next part of the procedure is tensioning and centralising the belt. This is done whilst running the unit so make sure that you have no loose clothes or neck tie which could tangle in it. It is done in the same fashion as a belt sander.

17) Make sure the wing nuts are easily loosened. Switch on the unit at a low speed.  Holding the wing nuts which are now loose move each side up and down in turn until a roughly central position of the belt on the rollers is achieved. The tension should be just enough to remove any oscillations from the belt. This can be observed through the side windows of the pillar. When this has been achieved tighten the wing nuts.

18) Switch off the unit.

19) Make sure the upper collector plate or comb is in contact with the belt

20) Clean the lower part of the dome with alcohol or meths and make sure the flange area of the outer edge of the dome where it connects with the upper part of the dome is particularly clean.

21) Clean the upper part of the dome and pay particular attention to the flange area on the inner edge of the dome where it comes it to contact with the lower part of the dome.  The unit is designed to produce a very high voltage but very low current (in the order of micro amps) therefore any build up of oxide or even grease from the hands can impede its performance. We recommend a light cleaning before every use.

22) Remove the crocodile clip from the bottom part of the dome and the flying end of the 4mm lead

23) Replace the upper part of the dome over the bottom part. Make sure it fits securely.

24) Connect the flying end of the 4mm lead to the end of the Discharge Sphere.

25) Switch on the unit and run it for 60 seconds, you should hear internal discharging, then bring the discharge sphere close to Van de Graaff Dome and you should achieve a 3 to 6 inch spark depending on conditions.

Note that the best spark is not necessarily obtained at maximum speed - adjust to suit.

The belt will wear in as the surface is not perfectly flat and some debris will accumulate in the bottom half of the Dome. This is perfectly normal. Just remove it occasionally and you will find the smoother the belt becomes the quieter it will get and the better performance will be achieved.

 Please contact STE if you should encounter any difficulties.