Errata for the beam indicator project.

Shackunit:
SW3 - The pin closest to the corner of the board should not be used. It was supposed to be an earth connection, it is instead a +5V connection. When wiring SW3 (if you want a calibrate funtion) use the pin closest to the 'S' of S3 as the active pin and take an earth connection from another switch.
If you will not be using the calibrate switch (it is not yet supported in software) you can wire a LED, anode to the +5V connection nearest the board corner, and cathode through a 330 ohm resistor to SW3 active pin. See the manual for detail but the LED will light when the moon/sun is in a forbidden area because the body is within "no go" territory set by limit switches in software.

If you plan to use a computer input it is necessary to do some clamping of the DTR signal from the computer. This is not shown in the circuit diagram and only became evident when using the 'pot' method of direction measurement togehter with computer input. I recommend you place a small silicon diode cathode on pin 4 of J1 and and anode to the direction of the RS232 connector to the computer (pin 20 of the DB25). Then solder a 5.1V zener diode between pins 4 and 5 of the J1. Cathode to pin 4, anode to pin 5. This arrangement ensures the RS232 voltage stays within about -0.1V and +5.1V. If you do not do this you will see that the readings from the pot vary slightly depending on whether the computer interface is working or not. The PICs do have internal zener protection but there must be a leakage current somewhere causing problems with the A/D. conversion.

AZ/EL unit:
The printed overlay of the 78L05 is reversed. So when locating the 78L05 insert it with the flat side pointing towards the PIC.

Encoder unit: no errors.
If you are new to using SM components like me follow this strategy.
Locate the AS5040 in position, make sure everything is aligned perfectly. 

Hold the chip in position with vertical pressure from a small screwdriver or aligning tool. 

Touch a soldering iron onto the pins along one side - the tinned board will act as the source of solder initially. 

Rotate the board and the now semi-attached chip. Tack the other side of the chip.

Now, using very fine solder apply small amounts of solder one or two pins at a time allowing it to flow, not worrying if you create bridges. Repeat until all pins have a small amount of solder.

Using solder wick remove the excess solder and bridges will disappear at the same time. 

By inspection and then using a multimeter, check that all pins are fastened to the board - use the 12 pin connector for one of the multimeter points. Once this is achieved use the 12 pin connector and the multimeter to identify if any bridges exist. 
You will need to apply the multimeter to the chip to check for bridges affecting pins 5,14,15 as these do not connect to the 12 pin connector. This is the time you discover your multimeter probes don't have a very sharp point.

The hardware will work with AS5040 and AS5045 using menu items.