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Start by trimming the RED lead on your JST cable down to 4 inches and the BLACK lead to 4.5 inches. Strip back these leads about 3/8ths inch. We will leave the YELLOW lead at its original length.
In the corner of the Nexus PCB next to right Mini DIN connector you will find two empy through holes labelled +5V and GND. Solder the RED lead into the +5V hole and the BLACK lead into the GND hole. |
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Counting from the opposite end of the board solder the YELLOW lead to the 9th pin on the edge of the PCB. This is the GPIO pin that drives the GREEN LED on your Nexus board.
Because the Watchdog PCB does not have a 40 pin header like the other boards, you can place it at either the top or the bottom of the stack using the standoffs included in the kit.
Route the 3 wire JST cable around a corner standoff and plug it into the white socket on the watchdog PCB.
The Nexus DR-X uses a DC barrel connector to power the stack. You can make a short version of this connector. Cut about six inches off then end of an old wall-wort power supply. Strip the two wires and connect them to the Vcc OUT screw terminals on the watchdog. Using your digital meter make sure that shield side of the plug is connected to the negative terminal and that the inner pin is connected to +.
When you are sure that the polarity is correct, plug this short 'pig-tail' cable into the DC barrel connector on the Nexus board. Plug your original Nexus power cable into the barrel connector on the watchdog PCB. Your Nexus should power up as it always has. The BLUE and GREEN LEDs on the watchdog should be ON. The GREEN LED is getting its power from the relay and it tells you that power is going to your Nexus. The BLUE LED gets its power back fed from your Nexus board. It is telling you that the Nexus is powered. If the GREED LED is ON and the BLUE LED is OFF, something is wrong with your connections.
You can also power the watchdog with the second set of screw terminals (ALT Vcc IN). However, be aware that alternate path using the screw terminals is automatically disconnected if there is a plug in the barrel connector.
Look for the GREEN LED on your Nexus board. You should see it flash every second or two. If it doesn't, use the 'Nexus Updater' in the 'Ham Radio' menu on your Raspberry Pi to update 'nexus utils'.
Some earlier Nexus boards do not have the GREEN LED. That is OK. As long as you have wired the JST correctly, the watchdog will still work.
Route the 3 wire JST cable around a corner standoff and plug it into the white socket on the watchdog PCB.
The Nexus DR-X uses a DC barrel connector to power the stack. You can make a short version of this connector. Cut about six inches off then end of an old wall-wort power supply. Strip the two wires and connect them to the Vcc OUT screw terminals on the watchdog. Using your digital meter make sure that shield side of the plug is connected to the negative terminal and that the inner pin is connected to +.
When you are sure that the polarity is correct, plug this short 'pig-tail' cable into the DC barrel connector on the Nexus board. Plug your original Nexus power cable into the barrel connector on the watchdog PCB. Your Nexus should power up as it always has. The BLUE and GREEN LEDs on the watchdog should be ON. The GREEN LED is getting its power from the relay and it tells you that power is going to your Nexus. The BLUE LED gets its power back fed from your Nexus board. It is telling you that the Nexus is powered. If the GREED LED is ON and the BLUE LED is OFF, something is wrong with your connections.
You can also power the watchdog with the second set of screw terminals (ALT Vcc IN). However, be aware that alternate path using the screw terminals is automatically disconnected if there is a plug in the barrel connector.
Look for the GREEN LED on your Nexus board. You should see it flash every second or two. If it doesn't, use the 'Nexus Updater' in the 'Ham Radio' menu on your Raspberry Pi to update 'nexus utils'.
Some earlier Nexus boards do not have the GREEN LED. That is OK. As long as you have wired the JST correctly, the watchdog will still work.