Author Topic: Fluke 87V MOV Replacements?  (Read 720 times)

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Offline darrylvaughan1

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Fluke 87V MOV Replacements?
« on: March 03, 2020, 02:38:54 am »
Hello,

Made a bonehead move and put my probes on some high voltage with my 87V in Resistance mode.

I blew at least one MOV as it was black. Voltage readings are wrong, resistance does not go to OL etc.......

How do I cross these BLUE MOV's from Fluke to get the right parts? (see pic)

Thanks,
Darryl

[attachimg=1]
 

Offline retiredcaps

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Re: Fluke 87V MOV Replacements?
« Reply #1 on: March 03, 2020, 03:50:42 am »
If you made an "oops" moment, you need to check all the input protection components for damage.  While some may be obvious, others are not.

1. All your blue MOVs should measure 0L in resistance mode.
2. Your green fusible resistor should measure around 1k ohm.
3. The green PTC should measure around 1.1k ohm.

Report your findings above.  All measurements can be made "in circuit" with another working meter.
« Last Edit: March 04, 2020, 02:48:08 am by retiredcaps »
 

Offline darrylvaughan1

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Re: Fluke 87V MOV Replacements?
« Reply #2 on: March 03, 2020, 04:02:11 am »
Thank You for the reply. I’ll get hold of another meter and post the results.
 

Offline darrylvaughan1

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Re: Fluke 87V MOV Replacements?
« Reply #3 on: March 03, 2020, 09:39:08 pm »
The three Blue MOV’s read 1.007 Meg, 2.98K, 4.15K.
PTC 4.46K
Fusible Resistor 1.024K

Measurements in-circuit.
 

Offline retiredcaps

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Re: Fluke 87V MOV Replacements?
« Reply #4 on: March 04, 2020, 02:43:54 am »
Desolder all 3 MOVs.  They are all bad.

With the MOVs desoldered, remeasure the green PTC.  It should be around 1.1K ohm. If not, desolder the PTC as well.

For testing purposes only, solder in a normal 1K ohm resistor in place of the PTC.  The 87V will work without the MOVs installed.  It just won't give you the high energy protection.

Retest the 87V with low AC/DC voltage measurements and small resistors.  If all works well, then you can buy new MOVs and PTC.

Fusible resistor is good.
« Last Edit: March 04, 2020, 03:00:24 am by retiredcaps »
 

Offline retiredcaps

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Re: Fluke 87V MOV Replacements?
« Reply #5 on: March 04, 2020, 02:52:17 am »
Parts list.

The replacement PTC, slightly bigger in size than the original, is YS4020.  You can find it on digikey or mouser.

https://media.digikey.com/pdf/Data%20Sheets/Thermometrics%20Global%20Business%20PDFs/YS4020_Spec.pdf

An older thread suggests these for MOVs.

https://www.eevblog.com/forum/testgear/fixing-a-fluke-87v/msg254744/#msg254744

All the usual disclaimers apply when repairing your own meter and using it in high voltage situations.

Edit: I mistakenly listed the YS4020 as a MOV.  It's not, it is a PTC.  I have corrected that above in my earlier post.  Sorry about that.  It's been a long couple of days.
« Last Edit: March 04, 2020, 02:59:40 am by retiredcaps »
 

Offline darrylvaughan1

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Re: Fluke 87V MOV Replacements?
« Reply #6 on: March 05, 2020, 08:16:23 pm »
Replaced MOV’s and PTC.

Meter is back up and checking good when compared to readings from another 87V.

Thank You Thank You!!!!!!!
 

Offline retiredcaps

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Re: Fluke 87V MOV Replacements?
« Reply #7 on: March 05, 2020, 09:27:22 pm »
Replaced MOV’s and PTC.
Wow, that was quick.  Did you order from digikey or mouser?
 

Offline retiredcaps

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Re: Fluke 87V MOV Replacements?
« Reply #8 on: March 05, 2020, 09:28:25 pm »
Also, can you post a picture of your repair?  I just want to see how the new MOVs and PTC fit, in terms of spacing.
 

Offline darrylvaughan1

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Re: Fluke 87V MOV Replacements?
« Reply #9 on: March 05, 2020, 10:46:50 pm »
Sorry, cannibalized parts from an old unit so OEM.
 

Offline retiredcaps

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Re: Fluke 87V MOV Replacements?
« Reply #10 on: March 06, 2020, 12:02:26 am »
If you replace the parts in the old one, please post a pic.

Thanks.
 

Offline floobydust

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Re: Fluke 87V MOV Replacements?
« Reply #11 on: March 06, 2020, 08:44:28 pm »
I've never seen distributors carry multimeter Epcos/TDK S05K575 MOV's. They are optimized for physical size and a custom part.
More here: https://www.eevblog.com/forum/repair/fluke-87v-105223/msg1443601/#msg1443601
 


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