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Author Topic: HP438A power meter not detecting sensors  (Read 1396 times)

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Offline geo00Topic starter

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HP438A power meter not detecting sensors
« on: February 15, 2018, 08:05:23 am »
Just got our HP438A back from cal and it boots up good with no errors other than No CH A error 31. Meaning no sensors hooked up to channel A. But even when I hook up a sensor it does not detect it, not on Ch A or B and I've tried different sensors and cables.

Any suggestions?
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Offline danadak

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Re: HP438A power meter not detecting sensors
« Reply #1 on: February 15, 2018, 12:17:06 pm »
Look at the operating theory section of manual for how the sensor
detection circuit works to get clues as to what is going on.


Regards, Dana.
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Love Cypress PSOC, ATTiny, Bit Slice, OpAmps, Oscilloscopes, and Analog Gurus like Pease, Miller, Widlar, Dobkin, obsessed with being an engineer
 

Offline Tony_G

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Re: HP438A power meter not detecting sensors
« Reply #2 on: February 15, 2018, 04:26:32 pm »
The input amplifier handles the detection of the sensor - Service Sheet BD3 is the correct starting point for that with Service Sheet 6 being the specific one for the Input Amplifier.

Assuming that you have confirmed the that sensors work on another unit, I would open the unit up and first check that the cables are properly seating to A4J2 & A4J3. After that follow the service sheets.

Good luck and let us know how it goes.

TonyG
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