Handy Board Assembly Tips

This page contains general hints for assembling the Handy Board. Some previous experience building and solder electronic components is assumed; for an introduction to soldering and how to mount electronic components, see Chapter 1 of the 6.270 Robot Builder's Guide.

Component Side versus Solder Side

The component side of the Handy Board is clearly marked COMPONENT SIDE, near the location where the piezo speaker is installed. The component side has the silkscreen legend printed on it---the white labels that indicate where the components are placed.

All components sit on the component side, with their leads poking through to the solder side. The board is then soldered from the solder side.

Don't get it backward because the board won't work, unless it is transported to a parallel universe.

The Square Pad Convention

On the Handy Board, square pads are used when a component is polarized and hence must be installed in a particular orientation. The square pad may have one of two meanings: Following is information on the specific components that are polarized:

The 6811

PCB Mounting

There is no square pad indicating pin 1 on the 6811. The 6811 is mounted in a PLCC (plastic leaded chip carrier) socket. The socket is soldered down to the board, and the 6811 is inserted into the socket.

The above diagram shows the 6811 socket, with its chamfered (or truncated) corner in the upper left. The 6811 itself has a matching chamfer in its upper left corner (the 6811's pin 1 is indicated with a dot).

It is imperative to install the PLCC socket with its chamfered corner directly above the chamfered corner of the silkscreen legend. This is because once the socket is soldered down, the 6811 only fits into it one way, so the socket must be soldered correctly.

6811 Pin Numbering

Several of the assembly steps require testing signals on the 6811 chip. This can be done either from the top of the chip, by inserting a thin wire to make contact with the actual 6811 leads, or from the bottom of the board at the PLCC socket leads.



6811 Chip Pin Numbering
TOP VIEW

Looking down at the 6811, the numbering of its pins proceed counter-clockwise from the pin 1 dot. E.g., pin 2 is immediately to the left of pin 1, and pin 52, the highest-numbered pin, is immediately to pin 1's right (see diagram above).



6811 PLCC Socket Pin Numbering
BOTTOM VIEW

There is a non-obvious translation from the simple numeric progression of the 6811 pin numbering to how the pins appear at the PLCC socket leads. The above diagram shows the pin numbering, looking up at the PLCC socket from the bottom of the PC board. In other words, the diagram shows the pin numbering assuming the board is turned upside down, and the viewer down at it.

Cutting Female Strip Header

Female strip header can be difficult to cut properly. If it is just snapped, it does not break cleanly between two pins; one pin adjacent to the break is generally destroyed.

A recommended method is to repeatedly score the header at the desired break point, using an X-acto or matte knife to gradually dig deeper and deeper into the cut line. Score the header several times on both sides of the groove between two socket pins until the header can be gently snapped by hand.

If done patiently, this process ensures clean breaks between the header sockets.


[next] [up]

Fred Martin / MIT Media Laboratory / fredm@media.mit.edu / Tue Jul 16 14:36:59 1996