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Electronics => Repair => Topic started by: kleblanc on July 23, 2017, 06:02:06 pm

Title: Fluke 726 PTC help
Post by: kleblanc on July 23, 2017, 06:02:06 pm
I have a Fluke 726 process calibrator that will not measure or source milliamps. I am curious is the PTC is an issue. One is read 110kohm and the other is 300kohm. I am attaching pictures, and I just measured without removing them.  The "square fuses" are around 8 ohms each.

Any help would be greatly appreciated.
Title: Re: Fluke 726 PTC help
Post by: retiredcaps on July 23, 2017, 06:26:50 pm
Quote from: kleblanc on July 23, 2017, 06:02:06 pm
I am curious is the PTC is an issue. One is read 110kohm and the other is 300kohm.
I'm not familiar with the 726 and I haven't searched for a service manual/schematics (I doubt one exists for the newer Flukes ), but in Fluke's handheld multimeters, the PTC is used for input protection on the volts/ohm input jack and is usually in the 1.0 to 1.1k ohm ballpark.

If this meter is not under warranty, you could, for test purposes only, remove the two PTCs and temporarily use two normal 1.0k ohm resistors to see if that corrects the issue?
Title: Re: Fluke 726 PTC help
Post by: retiredcaps on July 23, 2017, 06:28:19 pm
Quote from: kleblanc on July 23, 2017, 06:02:06 pm
I am attaching pictures, and I just measured with removing them.
I think you meant "without" removing them as your picture shows them being measured in-circuit.
Title: Re: Fluke 726 PTC help
Post by: Gyro on July 23, 2017, 06:30:41 pm
If it helps, I think those are Raychem parts.


Edit: Now Tyco.
Title: Re: Fluke 726 PTC help
Post by: kleblanc on July 23, 2017, 06:47:31 pm
Thank you Retired caps, yes I meant without. Mistyping from my phone...
I have not been able to find a schematic either. 
It is out of warranty so I must try that.

I am also hoping someone might have this Meter and be able to check theirs.

Gyro, the raychem lead is more than I had earlier.
Title: Re: Fluke 726 PTC help
Post by: lowimpedance on July 24, 2017, 03:19:49 am
Quote from: kleblanc on July 23, 2017, 06:02:06 pm
One is read 110kohm and the other is 300kohm. I am attaching pictures, and I just measured without removing them. 

Any help would be greatly appreciated.

 Quick check on that 34401 reading which is some what hard to see, but is that not a decimal point before the 110 as in ' 0.110,97 Kohm ' or nearly 111  \$\Omega\$  ??.
Title: Re: Fluke 726 PTC help
Post by: kleblanc on July 27, 2017, 11:03:27 am
I didn't even notice the decimal  :palm: . I'll have to recheck to see if the other one is 300 ohms or 300kohms.
Title: Re: Fluke 726 PTC help
Post by: JerryV on October 30, 2020, 07:10:03 pm
was this ever corrected? i have a Fluke that is doing the same thing
Title: Re: Fluke 726 PTC help
Post by: kleblanc on October 30, 2020, 07:14:16 pm
Unfortunately no, I sold it on eBay as parts