Author Topic: Fluke 87 doesn't turn off consistently.  (Read 3019 times)

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Offline corrado33

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Fluke 87 doesn't turn off consistently.
« on: May 04, 2014, 02:22:31 am »
Hi all,
Bought an 87 off of ebay the other day. The meter works great, all of the modes work and are accurate (as much as I can tell) however, the meter has a small problem. When in the off position, the meter sometimes flickers on and off repeatedly.  Sometimes I can even switch it to off and it stays on! It turns on to the AC voltage mode. I thought maybe the rotary switch was dirty or something, so I took it apart and worked the switch around... a lot. That didn't help. The problem can be reproduced by pushing on the upper (closer to the display) part of the rotary switch. Is it possible for the switch to have come misaligned somehow? Has anyone ever heard of this problem? Given the widespread popularity of the 87, I'd assume someone has seen it once or twice!

Thanks!
 

Offline xwarp

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Re: Fluke 87 doesn't turn off consistently.
« Reply #1 on: May 04, 2014, 03:59:24 am »
I just recently picked up a series 1 Fluke 83 and a series 1 Fluke 87, both of which did the same.

I did following to both, replaced batteries, cleaned the elastomeric contacts, and removed the section of the rotary switch on the back side of the board and cleaned those contacts. I also tweaked those "fingers" a tad so that a better contact would be made to the board.

Problem fixed, but I could not tell you which one.

I don't think a battery on the lower limits affects the meter that way when the switch is in the off position, but believe it goes into a reset loop when turned on.

 
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Offline corrado33

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Re: Fluke 87 doesn't turn off consistently.
« Reply #2 on: May 04, 2014, 05:26:46 am »
The first thing I did was change the battery. I've also just found that the battery contacts (on the 87 it's just a normal 9V connection with wires) were falling off. The ground was connected by a single strand of the wire.

I'll solder it up at work tomorrow and see how it acts then.

I also tweaked the contacts a bit to move them further away from the rotary part when it's in the "off" position.
 

Offline corrado33

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Re: Fluke 87 doesn't turn off consistently.
« Reply #3 on: May 04, 2014, 08:26:31 pm »
Well, I think I fixed it sufficiently. I cleaned the black conductive pads on the back of the board with some methanol (what I had around). I also cleaned the top of the rotary switch (the part that's accessible), and I soldered the battery leads back on. It seems to work better, doesn't flicker nearly as much as it used to. It'll still flicker if I REALLY flex the meter. (Dave's "solidness" test.) If I could clean the bottom of the rotary switch I bet it'd be perfect, but I'm not about to desolder and replace a rotary switch that works 99% of the time. Overall, I'm happy. Got a good deal on a great meter. It's definitely an old one though, date codes in the late 80s.
 

Offline retiredcaps

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Re: Fluke 87 doesn't turn off consistently.
« Reply #4 on: May 04, 2014, 09:55:03 pm »
You may find modemhead's website useful as it lists most of the known problems with the original Fluke 80 series along with some cleaning tips.

http://mrmodemhead.com/blog/all-posts/
 
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Offline turbo!

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Re: Fluke 87 doesn't turn off consistently.
« Reply #5 on: May 06, 2014, 02:58:11 am »
If cleaning doesn't work, there are a few possibilities: Surface of the board is worn, contact prongs are worn, or you could have a broken tension springs if your  meter uses it. When you push on the dial outwards, you should be able to tell if its a spring loaded switch. Be very careful not to lose the tiny ball bearings. There should be two balls and two springs.
 

Offline kenny

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Re: Fluke 87 doesn't turn off consistently.
« Reply #6 on: October 26, 2019, 07:25:39 pm »
Thanks for the good tips here, my 87 wouldn't turn off--it would turn on the backlight and blink and beep at any time and it drained the battery quickly.  i followed the tips here for cleaning and bending the fingers on the backside of the switch--now it works like new.  This thread was the first result from doing a web search, so it must get a lot of looks.
 


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