Mount the DC/DC step-down converter module
IC6 (OKI-78SR-5/1.5-W36C). The power inductor
on the module should point towards K1.
Mount MOSFET power transistor T5 (IRF644).
Please note that this is an electrostatic sensitive
device. It is recommended to touch an earthed
metal object before mounting the transistor. As
a better alternative, you can also wear an anti
static wrist strap and combine this with a
grounded ESD mat. The metal tab of the
transistor should point towards D1.
Mount the electrolytic capacitor C10 (10 μF 250 V). Watch the polarity!
Put IC7 (MC34063) in its socket. Watch the position of the notch!
Make sure trimmer potentiometer P1 is in its
middle position.
Power up the bord using a 9 V power supply
capable of delivering at least 500 mA. A lab
power supply with adjustable current limit is
preferable. Measure the nixie anode voltage
across 1 W resistor R28. Adjust the voltage to
approximately 170 V. Be careful not to touch the
170 V anode voltage and do not touch R28 as it
may get hot.
Now check the 5 V power rail voltage. You can
measure this voltage on pin header K1.
Do not continue the build of the clock if the
voltages are not correct but look for assembling
faults instead.
If everything is ok, disconnect the power supply.
