Logg instrument

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grävling
Inlägg: 49
Blev medlem: 01 aug 2012, 23:21

Logg instrument

Inlägg av grävling »

Jag har ett gammalt logginstrument Autohelm st 50 som visar tripp, djup, temp och fart
jag har ett mystiskt fel när vi är i skärgården och i salt vatten så visas temperaturen i vattnet korekt.
Men när vi kommer hem och vi är i sötvatten så visar det fel vatten temp ca 15-20 grader för varmt
finns det någon lösning på detta lilla problem ?
Lars Lundbladh
Inlägg: 1499
Blev medlem: 26 jul 2003, 23:46
Ort: Sweden
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Re: Logg instrument

Inlägg av Lars Lundbladh »

Hej,

Autohelm support sköts numera av Raymarin på deras FAQ sida kan man läsa följande OBS temperaturer i Farenheit :

Testing the Temperature Sensor:

The temperature sensor employs a thermistor as its sensing element. The impedance through a thermistor will change as the thermister temperature changes. Increases in temperature will cause a decrease in impedance through the thermister. Correspondingly, decreases in temperature will cause an increase in impedance through the thermister.

Example: If the thermister is immersed in water is 77 degrees F, the multimeter will report an impedance of approximately 10,000 Ohms. If the thermister is immersed in water is 68 degrees F, the multimeter will report an impedance of approximately 12,495 Ohms.

Other examples:

81 degrees F = 9,164 Ohms
77 degrees F = 10,000 Ohms
68 degrees F = 12,495 Ohms
61 degrees F = 15,004 Ohms
57 degrees F = 16,470 Ohms
54 degrees F = 18,098 Ohms
50 degrees F = 19,911 Ohms

It is not possible to directly test the thermistor. Testing is performed indirectly by applying a known resistance to the BROWN and WHITE terminals of the instrument display or instrument pod and noting the temperature reported by the instrument display.

Testing is performed as follows:
Power down the instrument
Disconnect the BROWN and WHITE transducer leads from the instrument display or pod.
Install a 10,000 Ohm resistor across the BROWN and WHITE terminals of the instrument display or instrument pod
Power on the instrument
The display should report a temperature of approximately 77 degrees F.

Should the display respond as indicated above, then the thermistor has failed and should be replaced. If not, then the instrument display or instrument pod has failed and should be serviced by Raymarine's Factory Repair Center.


/Lars
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