Author Topic: Fluke 52 II PCB missing passive component  (Read 828 times)

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Offline BlynskiTopic starter

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Fluke 52 II PCB missing passive component
« on: March 17, 2023, 07:24:16 pm »
I am trying to fix my dad's Fluke 52 II and it appears to have multiple issues.  Firstly, half of the header contacts had broken solder joins which I repaired.  Secondly, it appears to have some damage and a missing passive component (probably a capacitor based on how it is acting).  Attached is a picture I found of a good board with the missing component circled.  Does anyone know the correct value of this component so I can order one and replace it (or someone with a schematic)?
 

Offline fzabkar

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Re: Fluke 52 II PCB missing passive component
« Reply #1 on: March 17, 2023, 07:59:34 pm »
The colour is reminiscent of a precision resistor. What resistance do you measure for the "2742" part and for the other unmarked part?
 

Offline BlynskiTopic starter

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Re: Fluke 52 II PCB missing passive component
« Reply #2 on: March 18, 2023, 02:42:14 am »
Thanks for the hint on it being a resistor. I’ll take some measurements tomorrow and report back.
Assuming you are correct I would still need someone with a good board or a schematic to help me out on the needed value.
 

Offline fzabkar

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Re: Fluke 52 II PCB missing passive component
« Reply #3 on: March 18, 2023, 03:10:57 am »
The Linear part is a dual precision reference:

https://www.analog.com/media/en/technical-documentation/data-sheets/1034fe.pdf

That would lend support to the precision resistor idea.
 

Offline BlynskiTopic starter

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Re: Fluke 52 II PCB missing passive component
« Reply #4 on: March 19, 2023, 01:34:43 am »
Based on taking measurements on my board, I would agree that they are in fact resistors.  Picture attached of the measured values.  Essentially two  27.4k ohm and one 5k ohm resistor.  So at least I know I'm looking for a precision resistor, but still need the correct value...
 

Offline fzabkar

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Re: Fluke 52 II PCB missing passive component
« Reply #5 on: March 19, 2023, 05:37:58 am »
Just in case you don't have it, here is the service manual (but no circuits):

https://elektrotanya.com/fluke_51_52_53_54_series_ii_thermometer.pdf/download.html#dl

Your board is the "isothermal PCA". I suspect it provides cold junction compensation for the thermocouple.
« Last Edit: March 19, 2023, 05:42:23 am by fzabkar »
 

Online coppercone2

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Re: Fluke 52 II PCB missing passive component
« Reply #6 on: Yesterday at 06:36:50 am »
Ah I fixed mine after dropping it, I was very confused.


YOu see, that board has pins on it that are SMD! I thought they were through hole and figured there is no way that could break.
 


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