SC5 Signal Conversion Troubleshooting
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Troubleshooting
Instrument doesn’t power up correctly
SYMPTOM: The Power LED (3) does not light up.
REASON: Fuses blown.
SOLUTION: Disconnect the SC5 from the mains. Remove and check the fuses (5). If the fuses are blown,
replace them with fuses of the same rating (2AT, rated 250 VAC, 5×20 mm), and try powering up
the SC5. Should the fuses blow again, please contact SPECS.
REASON: SC5 damaged.
SOLUTION: Disconnect the SC5 from the mains. Remove and check the fuses (5). If the fuses are intact, but the
unit is still not working, please contact SPECS.
Auxiliary power supply doesn’t work correctly
SYMPTOM: When connecting the external device to the auxiliary power supply receptacle, the status
LEDs (8) start flashing with a frequency of about 5-10 Hz.
REASON: There is a short circuit in the power supply wiring of the external device.
SOLUTION: Unplug the external device and check if the positive and negative power supply rails of the
external device are shorted with respect to each other or to GND. If a short circuit is detected,
locate the source of the short circuit, and power the external device with the SC5 only when the
short circuit has been removed.
REASON: The external device is drawing too much current.
SOLUTION: Check for a short circuit as above. If there is no short circuit, the external device is drawing more
than 300 mA per rail from the SC5 auxiliary power supply, and should therefore be powered from
another power supply.
REASON: More than one device connected to the auxiliary power supply, and the total current consumption
exceeds 300 mA per rail.
SOLUTION: Connect only one external device to the SC5, or a number of devices whose current consumption
does not exceed 300 mA per rail.
SYMPTOM: There is a voltage offset between the GND of the power supply and PE or the experiment.
REASON: The device powered by the SC5 is not connected to any GND source.
SOLUTION: Make sure that the external device is connected to GND correctly. The auxiliary power supply of
the SC5 is fed from a dedicated winding of the power transformer, and the GND pins of the output
connector correspond to the center tap of that winding. These pins are referenced to GND over
either 5.1 kΩ, or 100 Ω (depending on the GND BNC connector) and the GND level can have an
offset of up to 6.5 V maximum with respect to PE (limited by a transient voltage suppression
diode).
SYMPTOM: The status LEDs (8) do not turn on, but the power LED (3) does.
REASON: The auxiliary power supply has been damaged.
SOLUTION: Please stop operating the instrument and contact SPECS.
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