Author Topic: Fluke 87V oscillating between K and M ohm ranges - cause and fix  (Read 2032 times)

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Offline ButWhatIfIAmARobot

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Thought I would share my fix (and vent) in case anyone else sees a similar problem.

So I bought my fist Fluke off eBay. A "good condition working" 87V for $190USD.  It arrived today, much dirtier than the pictures showed, screen scratched up...NEVER trust low-res pictures or a sellers ability to determine condition.  I should have known better.
    I found that when in the ohms function the screen continuously switched between K and M range (probes not even connected).  If I pressed down on the selector, the behavior went away and it remained in the mega ohms range.  I suspected wiper contamination since the outside was so grimy.  Instead, this is what I found (attached, sorry for the overly bright flash...).  The wipers were very clean, but obviously had been bent somehow.  Some of the plastic alignment features on the inside of the case were also crushed, and the insulation of the battery lead was damaged due to being crushed... OBVIOUSLY, if it doesn't fit, make it fit, right?  Anyways, I tweaked the wiper to where it should be, cleaned it up, and it now works as it should.  I assume that careless curiosity is the cause of the bent wiper.  Thankfully Fluke designed the meter with very few screws and only two sizes.

Edit: Anyone know the brand/series of the battery lead pcb header?  Molex or JST?
« Last Edit: October 08, 2016, 06:10:50 pm by ButWhatIfIAmARobot »
 

Offline retiredcaps

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Re: Fluke 87V oscillating between K and M ohm ranges - cause and fix
« Reply #1 on: October 10, 2016, 01:54:16 am »
Welcome to the forum and thanks for sharing your repair story with us.

When I first opened a Fluke 87V, I was all paranoid about breaking something because the fit is so tight.  Getting everything back together was just as difficult and I can see something taking "the hammer" approach if they have little patience.  Too bad the 87V doesn't allow you to change fuses without opening the entire case.

As for the battery lead pcb header, when I had to solder on a new one, it was just two wires going into the pcb.  However, the two wires were crimped at the very end.

I'll try to find a picture on the Internet to illustrate.
 

Offline retiredcaps

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Re: Fluke 87V oscillating between K and M ohm ranges - cause and fix
« Reply #2 on: October 10, 2016, 02:04:15 am »
I can't figure out what the part is called, but I blacked out the top half on the part and the bottom half is very similar to what I found on the 87V battery pcb lead connector.  The bottom half then goes through the pcb and soldered onto the other side.
 

Offline saturation

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Re: Fluke 87V oscillating between K and M ohm ranges - cause and fix
« Reply #3 on: October 10, 2016, 10:39:31 pm »
I can't tell between Molex vs JST.  However its cheap enough to buy both from the same vendor as shipping cost more.  From small quantities I get them from All Batteries or any RC store:

http://www.all-battery.com/jst-xhp-2p-80178.aspx



The Fluke part:

http://www.ebay.com/itm/U-S-A-Fluke-Battery-snap-cable-FLUKE-83V-85V-87V-88V-OEM-NEW-/252395947468?hash=item3ac3f885cc:g:nqAAAOSwQjZXPhV6

Best Wishes,

 Saturation
 

Offline retiredcaps

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Re: Fluke 87V oscillating between K and M ohm ranges - cause and fix
« Reply #4 on: October 10, 2016, 11:18:45 pm »
Hmm, now that I see the picture provided by saturation, maybe it was Fluke 87 original that I did the repair on?  So long ago, I don't remember now.
 


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