QCX assembly Rev 1.08
14
3.2
Install IC2 socket
Install the 28-pin IC socket for IC2. Take care to match the dimple on the socket, with the dimple
on the PCB silkscreen. It is critical to insert the microcontroller with the correct orientation. Lining
up the dimple on the PCB silkscreen, socket and actual IC is the best way to avoid confusion and
potential error.
I recommend soldering one pin at each diagonal, for example pins 1 and 15. You can then check
that the IC socket is seated firmly on the PCB, and correct any issues easily. Once all the pins are
soldered it will be difficult, if not impossible, to change anything. When you are happy with the
position of the socket, proceed with soldering the other 26 pins.
3.3
Install DIP integrated circuits IC3, IC5-10
In the same way, install the Dual-Inline-Package integrated circuits IC3 and IC5-10. We install
these now because they have more pins than all the passive components (resistors, capacitors
etc) and it is easiest to reach and install the ICs properly when they are alone on the board. All of
the operational amplifier ICs (IC5-IC10) are part number LM4562, so it is impossible to mix them
up, they are the only 8-pin DIP chips in the kit. Similarly, IC3 is the only 14-pin DIP chip.
Electrostatic Discharge (ESD) precautions should be observed though personally I do not think it
is necessary to get crazily paranoid about this. Don’t wear 100% nylon clothing and dance around
on a nylon carpet etc to build
up static charge! But I don’t go to the other extreme of earth mats,
earthed wrist bands etc.
It IS absolutely critical to align the IC’s properly! Be very careful to check and double-check and
even triple-check that the dimple in each IC package is aligned with the dimple in the silkscreen
print on the PCB (and the layout diagram).
Содержание QCX 5W CW
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Страница 26: ...QCX assembly Rev 1 08 26 3 19 Install 20MHz crystal XTAL1 The engraving on this crystal is 20 000...
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