7
General
Service Handling Precautions
Service work or calibration should only be carried out by skilled engineers using high quality test
equipment. If the user is in any doubt as to his competence to carry out the work, the instrument
should be returned to the manufacturer or their agent overseas for the work to be carried out.
This simplified service guide only details the routine calibration procedure and the dismantling of
the instrument to PCB assembly level. If a PCB assembly is suspected as being faulty it should
be returned to the manufacturer or their agents overseas for repair or replacement. The Parts
List gives the part numbers of each PCB assembly, together with the mechanical parts and
fasteners that can be easily replaced by the user.
Dismantling the instrument
WARNING!
When the instrument is connected to its supply, terminals may be live and opening the covers or
removal of parts (except those to which access can be gained by hand) is likely to expose live
parts. The apparatus shall be disconnected from all voltage sources before it is opened for any
adjustment, replacement, maintenance or repair.
Any adjustment, maintenance and repair of the opened instrument under voltage shall be
avoided as far as possible and, if inevitable, shall be carried out only by a skilled person who is
aware of the hazard involved.
1. Disconnect the instrument from all voltage sources.
2. Unclip the front bezel by gently pulling the centre of each long edge up and forward.
The case halves are held together by 4 plastic push-rivets. Use the blade of a small
screwdriver to remove the rivets*. Place the instrument upside down on the bench and
separate the case halves by removing the case lower. Only the case lower need be
removed to gain access to all the adjustments necessary for calibration.
3. To remove the individual assemblies, firstly remove the screws securing the MAIN PCB to
the case upper and lift out the PCB with front and rear panels attached.
4. The front panel assembly may be removed as follows. Remove the nut on the front panel
metalwork securing the green/yellow safety earth wire to the front panel metalwork.
Disconnect the two 16-way ribbon cables from PJ1 and PJ2 on the MAIN PCB.
Disconnect the four 2-way connectors from PJ4, PJ7, PJ8, and PJ11 on the MAIN PCB.
Use a soldering iron to desolder the two cables from the MAIN OUT and SYNC output
BNCs. Finally locate the MAIN Board PCB Screen (which is fitted above the switchbank)
and remove the screw that connects the MAIN Board PCB screen to the Control PCB.
The front panel assembly can now be separated from the MAIN PCB; take care not to
damage the switchbank whilst the front panel assembly is lifted clear.
5. To remove the CONTROL PCB from the front panel, first, with the aid of a soldering iron
desolder the wire that connects the AM/COUNT IN BNC to the CONTROL PCB. The wire
must be desoldered from the CONTROL PCB not the BNC; the wire can then be
straightened perpendicular to the CONTROL PCB allowing for simple disassembly and
reassembly. Remove all of the knobs from the front panel (including rotary encoder, AM
DEPTH, SYMMETRY, OFFSET and AMPLITUDE). Remove the seven screws securing
the CONTROL PCB to the front panel metalwork. Carefully lift off the CONTROL PCB
ensuring that the front panel metalwork is kept level and facing downwards to prevent the
loss of unsecured keycaps.
