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Questions re Switches on Development Board

Discussions pertaining to the electrical issues (e.g. circuitry, power, etc.) of Pumpkin's CubeSat kit.

Questions re Switches on Development Board

Postby Unregistered User » Tue Apr 14, 2009 6:02 am

After soldering the connections between the switch and corresponding outputs we were expecting to have full functionality with the Remove Before Flight (RBF) and the Separation switch. We tested the RBF switch by shorting the pins H2.33-34 to H2.41-44, we than connected a multi-meter to test the connection, we than turned on the switch and expected the circuit to be complete. Unfortunately, the multi-meter did not detect a connection. We than tested the Separation switch by shorting H2.35-36 to H2.33-34 and H2.41-44. We than attached a multi-meter and as before expected a completed circuit once the Separation switch was activated. The Multi-meter detected a complete circuit, so the separation switch works properly. We are now trying to figure out why the Remove Before Flight switch did not work. Is this the correct way to test that switch? Thank you.
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Re: Questions re Switches on Development Board

Postby aek » Tue Apr 14, 2009 6:23 am

1. Please refer to pages 5 and 6 of the Dev Board schematics (00194C-5.PDF & 00194C-6.PDF) for information on the RBF and Deployment Switches. This shows the relationship between the switch C, NC and NO contacts, and the CubeSat Kit Bus connectors S0 through S5.

2. Do not confuse the means whereby the Clyde Space EPS uses the RBF and Deployment Switches, and the way the CubeSat Kit is designed. the RBF switch is connected to S0, S2 & S4, and the Deployment Switch is connected to S1, S3 & S5. Therefore those (and only those) signals are what you should be checking. The pins numbers you mention are associated with how the Clyde Space EPS utilizes the S0-S5 signals. Those connections are not valid, for instance, if the Clyde Space EPS is not plugged into the CubeSat Kit Bus.

3. All Dev Boards and switches are tested at Pumpkin before shipping to a customer. To test a particular switch, I would verify with a voltmeter directly on the switch contacts that C and NC are connected when the lever is out, and C and NO are connected when the lever is in. Then I would check for continuity from the terminal of each switch to the corresponding terminal / plated hole on the PCB itself. Lastly, I would check for continuity from the terminal on the switch to the associated pin(s) on connector H2. Examine the soldering on the connectors H1 and H2 as well.

4. Sticking wires into the H1 or H2 connectors is strongly discouraged. Those PC/104-type connectors are designed to mate only with other PC/104 or compatible connectors. If you need a "flying lead" connection with which to probe, then get a standard 0.025" square pin on 0.100" centers male header, solder a wire to the short end of the pin, and stick the long end of the pin into H1 or H2. Since H1 and H2 are designed to accept 0.025" square pins, this will not damage them.

5. We recommend 16AWG solid copper wire to connect the switches on the Dev Board to the S0-S5 terminals associated with them. Also, 16AWG solid copper for the RBF switch on the FM430. We recommend 18AWG stranded insulated wire for the Deployment switch on the FM430.

6. Judging from the quality of the soldering in the submitted pictures, it is possible that you may have damaged the switch with excessive heat on the terminals. However, that is unlikely. I would recommend that you check the switch directly on the terminals (as above), to ensure that it is still working properly. Replacement switches are E62-10K at Digi-Key.


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