Gemini Two Tube Clock
18
Update #1 (21
st
May 2019)
www.nixology.uk
First Test
–
Setting the 5V supply.
With
ONLY
the Buck converter mounted on the board, connect a 12V supply to
the PCB at the points provided taking care to connect the supply the right way
around and measure the output of the Buck converter with a multimeter by
using the GND and 5V test points. Adjust the potentiometer with a small
screwdriver until 5v is measured.
IT IS IMPORTANT THAT NO OTHER
COMPONENTS ARE PLUGGED IN TO THE BOARD AT THIS STAGE AS THE
BUCK CONVERTER WILL ALMOST CERTAINLY BE SET TO OUTPUT MORE
THAN 5V WHICH COULD DAMAGE OTHER COMPONENTS.
<Picture of 5V Test>
Do not proceed until you have a solid 5V reading.
Disconnect the 12V supply.
Second Test
–
checking the 170V supply
Inset the NCH8200HV power supply into the sockets on the board. Re attach the
12V supply and check that 170V is being produced by the NCH8200HV by
connecting a multimeter to the GND and HV test points.
<Picture of 170V Test>
Do not proceed until you have a solid reading in the region of 170V to
174V.
REMOVE THE POWER CONNECTION
Continue as follows:
Plug in the following on the top side of the PCB
2 x 74141 or K1551D1 drivers and 1 x 74595 shift register into their respective
locations according to the markings on the PCB taking care to align the notch on
each IC with the notch on the socket and PCB.
2 x EL817 Opto Couplers taking care to align them correctly. Pin 1 has a small
‘dot’ and should be located towards the edge of the PCB.
1 x BMP280 sensor module
–
this can be mounted directly or via a length of
cable if remote mounting is preferred. If it is not properly connected then the
temperature and pressure will not be displayed.
