Maintenance
6-16 2715 Spectrum Analyzer Service Manual
NOTE. Disconnect the instrument from its power sourcebefore replacing or
soldering components.
Extreme caution must be used whenremoving or replacing components, because
the instrument contains severalmulti layer circuit boards. Excess heat from the
soldering iron and bent component leadsmay pull the plating out of the hole.
Some circuit boards do contain leadedcomponents. To remove the component
leads, use a 15 W (or less) pencil type soldering iron. Straighten the leads on the
back side of the board; whenthe solder melts, gently pull the soldered lead
through the hole. A desoldering tool should be used to removethe old solder.
Use a desoldering tool that has alow build up of static charge, such as Silverstat
Soldapullt desoldering tool, when unsoldering integratedcircuits or transistors.
Transistor and Integrated Circuit Configurations. Lead identification fortransistors
and integrated circuits is readily avail able from manufacturer’s data books.
Integrated circuitpin outs for Vcc and ground are shown with a box on the
schematic diagram.
Diode Color Code. The cathode of each glass encased diode is indicated by a
stripe, a series of stripes, or a dot. Some diodes have a diode symbol printed on
one side.
Resistor Values.S urfacemounted resistors have no visible identification.
However, the value can be measured with a meter. Other types of resistors (s uch
as composition, metal film, tapped,thick film resistor network package, and
plate) are also used. The value i s either color coded in accordance with the EIA
color code or printed on the body of the component.
Capacitor Marking. Surface mounted capacitors(chip capacitors) have no visible
markings. The capacitancevalue, voltage rating, and polarity of electrolytic
capacitors are markedon the side of the component body. The ceramic tubular
capacitors and feedthrough capacitors are color coded in picofarads.
Multiple Terminal(Harmonica) Connectors. Some intercircuit connections are
made through square pin connectorsthat are mounted in a harmonica type
holder. If one of the pins must be replaced, all the pins at th at location must be
replaced as a set. Most ribbon cable connectors are key6ed. Exceptions are: two
pin connectors, the three pin connector at the back of the Log board, and the 50
pin connector between theMicroprocessor, Display Storage, and Digital Options
boards. The key location on the circuitboard is identified by a missing pin.
Soldering Techniques