Author Topic: FLUKE 287 no temperature compensation  (Read 1325 times)

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Offline NeonphoenixTopic starter

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FLUKE 287 no temperature compensation
« on: November 23, 2021, 11:40:23 pm »
I have a used FLUKE 287 I picked up to use with temperature calibrations. The problem I am having is when I'm outside in the cold the temperature reads higher than it should and when inside a hot building it reads lower than it should. I'll put my thermocouple in an ice bath and warm up the FLUKE on my dash abs watch the temperature drop. It's like it is not compensating for the internal temperature of the mainboard. Any idea where to look to fix this? Schematics perhaps? Thanks
 

Offline NeonphoenixTopic starter

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Re: FLUKE 287 no temperature compensation
« Reply #1 on: November 26, 2021, 03:04:59 am »
Inside temp about 10°C with thermocouple in an ice bath
Outside temp about 0°C with thermocouple in an ice bath
 

Offline Greybeard

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Re: FLUKE 287 no temperature compensation
« Reply #2 on: November 26, 2021, 08:21:17 am »
You can check the internal temp sensor by using a short bar at the input jacks.
Display should show DMM's internal temperature.
Check at room temparature, cold device (outside your home) and warm device (room heating, hair dryer...).
 

Offline NeonphoenixTopic starter

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Re: FLUKE 287 no temperature compensation
« Reply #3 on: November 27, 2021, 04:02:50 am »
That is a fantastic bit of information. Thank you. I did check it: grabbed it from the cold truck it read about 4°C.  After leaving it to acclimate to the room temperature, it read about 16°C then again about 22. Using the hair dryer it slowly climbed to 28. I put it back outside and checked it in 5 mins and it was reading 30+. Checked in another 5 and, although cold to the touch, it read 26 and slowly falling.  Sitting on the desk for a couple mins and it is 22. It seems like the thermal sensor is working but very slowly. Testing it against a new 725 there is no comparison as to performance. Could the thermal sensor be getting weak or failing in some manner? Do you know the part number if I were to replace it? Thanks again. Very helpful.
 

Offline Greybeard

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Re: FLUKE 287 no temperature compensation
« Reply #4 on: November 27, 2021, 12:04:35 pm »
Of course a temp sensor could fail. Is it just following very slowly the real temp or is it "jumping around"?
I'd give it an hour to acclimate.

And no, I don't know the part no of the temp sensor.
Have you asked Fluke?
 

Offline NeonphoenixTopic starter

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Re: FLUKE 287 no temperature compensation
« Reply #5 on: November 28, 2021, 05:49:21 pm »
The temperature seems to be accurate but following very slowly. The 725 I've used didn't seem to have this issue. I go from outside to a hot compressor building back to outside. Always changing environments. If I have to wait 30+ mins for my fluke to acclimate, my productivity will go out the window. I'll see if FLUKE will give me the part number but I'm not holding my breath. Thanks again.
 

Offline Greybeard

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Re: FLUKE 287 no temperature compensation
« Reply #6 on: November 30, 2021, 10:05:24 pm »
The temperature seems to be accurate but following very slowly. The 725 I've used didn't seem to have this issue. I go from outside to a hot compressor building back to outside. Always changing environments. If I have to wait 30+ mins for my fluke to acclimate, my productivity will go out the window.
I think 30 to 60 minutes to acclimate is normal.
All conductors of the instruments (not only the internal temp sensor) need to come to environment temperature.
« Last Edit: December 01, 2021, 05:15:40 pm by Greybeard »
 


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