General - Wavetek 39A Maintenance Manual

Service Handling Precautions
Service work or calibration should only be carried out by skilled engineers. Please note the
following points before commencing work.
Most of the integrated circuits are CMOS devices and care should be taken when handling to
avoid damage by static discharge. Also most devices are surface mounted miniature components
with very fine leads on small pitches. These components must be removed and replaced with
great care to avoid damage to the PCB. It is essential that only the proper tools and soldering
equipment as recommended for surface mount components are used.
The decoupling capacitors associated with the integrated circuits are surface mounted on the
solder side of the PCB.
Dismantling the Instrument
Disconnect the instrument from all voltage sources before it is opened for adjustment or repair. If
any adjustment or repair of the opened instrument is inevitable it shall be carried out only by a
skilled person who is aware of the hazards involved.
1. Remove the six screws retaining the top cover.
2. The rear panel may be removed as follows. Disconnect the grey ribbon cable from PJ6 on
the GPIB PCB. Invert the instrument and remove the three screws securing the rear panel
and the nuts securing the 9-way RS232 connector to the rear panel. The panel may now
be tilted back to allow access. If the panel is to be completely removed the connectors
must be removed from PJ3, PJ7, PJ8 and PJ11, the blue and brown wires disconnected
from the mains inlet filter and the blue and brown wires unsoldered from the mains
transformer. Cut the ties holding the cable assembly to the side instrument chassis. The
panel is then completely free of the instrument.
3. The front panel assembly may be removed as follows. Remove the connectors from PJ2,
PJ4, PJ12, PJ13 and PJ200 and desolder the screened cable from PJ202. Remove the
two nuts and bolts in the sides and two screws in the bottom of the instrument securing
the front panel assembly. The panel may now be drawn clear of the instrument.
4. Main pcb removal. Remove all connectors from the pcb and desolder the screened cable
from PJ10. Tilt the rear panel away as in 2 above. Remove six screws and lift away the
main pcb. When re-assembling the instrument ensure that all fixings use the correct
fastenings.
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WARNING!

General