DT80 Vos 3W

bfarrugia

posted Jul 19 '23 at 4:20 am

When running a test on one of our DT80s, it sometimes fails on Vos 3W II. What does that mean and is it repairable?
Is there a list available of the test line items and what they represent?

VEXT                  13.4   V
VBAT (6V)             6.50   V   PASS
IBAT                    +4  mA   PASS
VSYS                  7.05   V   PASS
VLITH (3.6V)          3.63   V   PASS
VDD (3.3V)            3.28   V   PASS
VANA (3.8V)           3.60   V   PASS
VRELAY (4.5V)         4.85   V   PASS

VREF (2.5V)        2499.86  mV   PASS
Ics I              0.21254  mA   PASS
Ics II              2.5595  mA   PASS
Vos diff               6.6  uV   PASS
Vos 3W I              59.8  uV   PASS
Vos 3W II          -1185.0  uV   FAIL
Vos shunt            -30.7  uV   PASS
Vos +                  5.6  uV   PASS
Vos -                  4.2  uV   PASS
Vos *                  6.2  uV   PASS
Vos #                -58.6  uV   PASS
Vos diff atten        63.4  uV   PASS
Vos + atten           63.2  uV   PASS
Vos - atten           63.2  uV   PASS
Vos * atten           63.5  uV   PASS
Term. factor       1.00470       PASS
Shunt (100R)        99.869 Ohm   PASS
CMRR                 123.1  dB   PASS

Overall health                   FAIL

When running a test on one of our DT80s, it sometimes fails on Vos 3W II. What does that mean and is it repairable? Is there a list available of the test line items and what they represent? ```` VEXT 13.4 V VBAT (6V) 6.50 V PASS IBAT +4 mA PASS VSYS 7.05 V PASS VLITH (3.6V) 3.63 V PASS VDD (3.3V) 3.28 V PASS VANA (3.8V) 3.60 V PASS VRELAY (4.5V) 4.85 V PASS VREF (2.5V) 2499.86 mV PASS Ics I 0.21254 mA PASS Ics II 2.5595 mA PASS Vos diff 6.6 uV PASS Vos 3W I 59.8 uV PASS Vos 3W II -1185.0 uV FAIL Vos shunt -30.7 uV PASS Vos + 5.6 uV PASS Vos - 4.2 uV PASS Vos * 6.2 uV PASS Vos # -58.6 uV PASS Vos diff atten 63.4 uV PASS Vos + atten 63.2 uV PASS Vos - atten 63.2 uV PASS Vos * atten 63.5 uV PASS Term. factor 1.00470 PASS Shunt (100R) 99.869 Ohm PASS CMRR 123.1 dB PASS Overall health FAIL ````

dataTaker Expert

posted Aug 2 '23 at 4:19 am

Hi bfarrugia,

The failure on Vos 3W II is usually because of a ground loop coming from the respective sensor. You need to trace which sensor gives you this error and eliminate it fast otherwise it will become permanent. And yes, we can repair the fault after become permanent.

Ics I and II represent the current excitation 213 uA and 2.5 mA, while Vos / +/ -/# represents the floating voltage on the respective pins. Internally the logger is some sort of multiplexer, all the terminals' pins are connected to a bus. For example, 1, 2, 3, 4, and 5 are connected to * bus. When none of the relays is triggered, whatever voltage in each bus is measured.

The shunt is an internal shunt resistor for current measurement, CMRR is self-explanatory. The other Vos are more combination measurements, 3W I is a 3-wire using current excitation I the same with 3W II.

Best regards,
dataTaker Expert

Hi bfarrugia, The failure on Vos 3W II is usually because of a ground loop coming from the respective sensor. You need to trace which sensor gives you this error and eliminate it fast otherwise it will become permanent. And yes, we can repair the fault after become permanent. Ics I and II represent the current excitation 213 uA and 2.5 mA, while Vos */ +/ -/# represents the floating voltage on the respective pins. Internally the logger is some sort of multiplexer, all the terminals' pins are connected to a bus. For example, 1*, 2*, 3*, 4*, and 5* are connected to * bus. When none of the relays is triggered, whatever voltage in each bus is measured. The shunt is an internal shunt resistor for current measurement, CMRR is self-explanatory. The other Vos are more combination measurements, 3W I is a 3-wire using current excitation I the same with 3W II. Best regards, dataTaker Expert

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