Mounting the tubes
The tubes must be mounted carefully so that they sit neatly over the top of the RGB LEDs, and
so that they are upright and parallel. It is quite tricky to mount the tubes, so take your time and
read through the instructions carefully before you start.
It is
VERY
hard to correct mistakes made on mounting the tubes, so plan out each move you
make and think it through.
Important!
Install the tubes one at a time and test after each tube is installed!
It is very hard to locate where an error is if a tube is faulty or you make a solder
bridge by mistake, because all the tubes share the cathode control lines.
To help in locating a bad tube or a construction error, test the display after you
install each tube, and deal with any issues that appear before moving on.
Start with the seconds tube and move to the hours tube, and let the test run for
about 30 seconds each time, so each cathode is tested.
The
pin out diagram is viewed from the bottom of the tubes
. Pins 2 and 13 are decimal
points, and are often removed on the tubes. The other pins are given below.
Pin
Connection
1
Anode
2
Left decimal point
3
Digit 1
4
Digit 2
5
Digit 3
6
Digit 4
7
Digit 5
8
Digit 6
9
Digit 7
10
Digit 8
11
Digit 9
12
Digit 0
13
Right decimal point
Installing the tubes is quite a fiddly process, and it can take a long time and plenty of patience.
Please see the hints below for some ideas how to make the process easier.
•
It is best to carefully spread the legs of the tube out so that they are not all bunched up.
If you have long enough leads, a trick is to trim the leads to different lengths so they get
shorter by 0.5mm as you go round the tube. This means that pin 3 is shorter than pin 1
by 0.5mm. Pin 4 is shorter than pin3 by 0.5mm and so on. Pin12 is shorter than pin 3 by
5mm at the end. This means that you can thread the leads into the holes more easily.
•
You can remove the decimal point leads on each side of the anode (pins 2 and 13) if you
want – they are not used. Remember to leave an unpopulated hole on the board on each
side of the anode in this case. Be careful to trim the right leads if you want to remove
them!
•
Place the tube base against the top of the LED, without leaving a gap.
