THG TIM 2015, Техническое руководство

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TIM 2015 Technical Manual v1 (February 2018) Page 16
Chapter 3 Troubleshooting
This chapter is in two halves. The first Chapter lists faults that may occur during construction and prevent you from getting TIM 2015 to
work at all, whilst the second section covers things that may come to light once you start using the completed clock.
The companion User Manual lists other problems that may crop up during use of TIM 2015.
Note that problems are frequently caused by unsoldered or badly soldered joints on the track side (underside) of the PCB. Visual
examination with a magnifying glass in bright light is the way to go. These words on good soldering are adapted from Wikipedia has these
wise words.
The most common defect when hand-soldering results from applying the solder before the parts being joined are heated enough. If
their temperature is not higher than the solder’s melting point, the result will be a
cold solder joint . This is usually the result of the
soldering iron being used to heat the solder directly, rather than the parts themselves. Properly done, the iron heats the parts to be
connected, which in turn melt the solder, guaranteeing adequate heat in the joined parts for thorough wetting by the flux embedded
in the solder.
Therefore, heating the solder first may cause the flux to evaporate before it cleans the surfaces being soldered. A cold-soldered joint
may not conduct at all, have
high resistance or may conduct only intermittently or noisily. Cold-soldered joints are a common cause
of equipment which passes testing, but malfunctions after sometimes years of operation.
A dry joint occurs when the cooling solder is moved, and often occurs because the joint moves when the soldering iron is removed
from the joint. Moving the part being soldered before the solder has cooled will cause a highly unreliable cracked joint. A dry joint
has a characteristically dull or grainy appearance immediately after the joint is made, rather than being smooth, bright and shiny.
This appearance is caused by crystallization of the liquid solder. A dry joint is weak mechanically and a poor conductor electrically.