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Old 30th Oct 2020, 1:06 pm   #1
retailer
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Default Fluke 87 multimeter overload

I'm rigging up a DC HT power supply and forgot I had been measuring mA with my Fluke 87 - touched the probes on the chassis and main filter cap (390V DC) and bang! - the display went blank for a few seconds and then came back on flashing and beeping - turned it off and then back on again but no function worked, volts measured low, display flashed and beeped would not settle on a range, my Fluke must be toast I thought - not a happy thought either.
Took me a few hours to get over the shock and to stop calling my self an idiot before I discovered the battery had gone flat almost at the same time I touched the probe on the capacitor, a new battery and it was all good, I was amazed it survived, the tip of the probe had been vaporized, I've damaged digital meters before with a much smaller overload.
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Old 30th Oct 2020, 2:04 pm   #2
MrBungle
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Default Re: Fluke 87 multimeter overload

The 87 is extremely well over engineered.

Saying that I ran my Brymen pocket DMM up to over 2kv until it made some unpleasant arcing noises and that still works fine!
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Old 30th Oct 2020, 3:30 pm   #3
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Default Re: Fluke 87 multimeter overload

You might need a new fuse for the mA input even if the Volts ranges work again.
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Old 30th Oct 2020, 5:15 pm   #4
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Default Re: Fluke 87 multimeter overload

I did the same with my 83-iii a few years ago. The fuse saved the day and the cost of the replacement certainly makes me think twice now!
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Old 30th Oct 2020, 11:21 pm   #5
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Default Re: Fluke 87 multimeter overload

With my initial thoughts being that the meter was beyond repair I did checkout prices for used 87's - even older models like my series III are listed on Ebay from $200 and up, while I can afford it I'd find it hard to justify - there are just so many under $100 true RMS meters available now, I wonder if they would survive the same type of overload.
The fuse did blow I've ordered a new plus a spare - I wasn't expecting a $10ea price tag though.
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Old 31st Oct 2020, 6:44 am   #6
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Default Re: Fluke 87 multimeter overload

I'm always doing similar things to my Fluke 25's, mainly HT whilst on the ohms range. The 25 has three big MOV's to soak up spikes, suppose the 87 has similar.

Andy.
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Old 31st Oct 2020, 10:02 am   #7
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Default Re: Fluke 87 multimeter overload

We had a Fluke 8020 for evaluation back in 1977 so we gave it a few tests to see if it was bullet proof. One test we tried was to measure the resistance of the mains! It passed and survived. I'm not going to deliberately try that with my 79 but it's good to know that Fluke have gone to a lot of trouble in the design to make it idiot, or engineer, proof.

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Old 31st Oct 2020, 3:35 pm   #8
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Default Re: Fluke 87 multimeter overload

I zapped my Fluke 23 with over 1KV from a TV line output stage once! It shut down, and I thought I’d knackered it, but touched the hold button and it sprang back into life, it’s still one of the best meters I’ve ever had, the only thing letting it down is the plastic case is cracked up near the display. I retired it when I got a Fluke 111.

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Old 31st Oct 2020, 3:44 pm   #9
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Default Re: Fluke 87 multimeter overload

Flukes are very well protected. They have proper safety category ratings too which can help protect the user also.
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Old 31st Oct 2020, 6:17 pm   #10
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Default Re: Fluke 87 multimeter overload

I'm pleased to read this. After all these years I'm about to take delivery of my first Fluke - a second-hand 89 IV. I've yet to blow a cheap meter but it has to happen sooner or later. In the end the moving parts (4mm connectors and rotary switch) become unreliable and I think the cal has drifted on at least some of them (it has to have done - they disagree about the mains voltage !).

Cheers,

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Old 1st Nov 2020, 1:00 am   #11
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Default Re: Fluke 87 multimeter overload

There is a Fluke video taken by a visitor to their factory. They take a cheap Chinese meter, show that it reads 600V when 600V is applied. The then switch it to ohms and turn on the 600V - it goes up like an incendiary.

https://www.youtube.com/watch?v=OEoazQ1zuUM

He then takes a Fluke 87 and connects 600V, and then turns the selector across all ranges back and forth. Absolutely nothing happens. No drama. Returns to DCV and 600V is read.

I really would not buy anything other than Fluke - you know for sure it is not going to burst into flames in your hand!

Craig
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Old 1st Nov 2020, 9:27 am   #12
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Default Re: Fluke 87 multimeter overload

I have been using a Fluke 11 for 30 or 40 years and have inadvertently tried to measure the resistance of the mains on a number of occasions, all that happens is that it shouts at you. I have never met anyone that has succeeded in destroying one

I bought mine after destroying several other digital meters, it was very expensive at the time but it has sure paid for itself. The LCD display is beginning to degrade now but it still works perfectly.

Peter
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Old 1st Nov 2020, 11:47 am   #13
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Default Re: Fluke 87 multimeter overload

I got my Fluke (8020B I think) when I was an apprentice in 1981 (company issue), I was always amazed that it only went "beep beep..." when measuring the mains resistance as described above. Never did blow it up but lost it 30 years ago, it survived a 30 foot drop onto tarmac.
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Old 1st Nov 2020, 1:47 pm   #14
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Default Re: Fluke 87 multimeter overload

Quote:
Originally Posted by Peter.N. View Post
The LCD display is beginning to degrade now but it still works perfectly.

Peter
Probably just needs the elastomeric (zebra) strip contacts cleaning.

Flukes really are the industry standard. There's no way I'd go back to using cheap DMMs.

Alan
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Old 1st Nov 2020, 3:23 pm   #15
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Default Re: Fluke 87 multimeter overload

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it survived a 30 foot drop onto tarmac.
When one of our riggers did the same with a 73 it didn't. I acquired it as scrap and found that the chip had unglued itself from the PCB. Some microsurgery restored it to health and I've used it for around 15 years since. Not even a crack in the case!
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Old 1st Nov 2020, 5:20 pm   #16
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Default Re: Fluke 87 multimeter overload

Luckily my Fluke 115 has survived a few drops, even from the height of the top of a full colour web offset press. Perhaps the day will come where it's had one too many drops, but I do try to not drop it.
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Old 1st Nov 2020, 7:16 pm   #17
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Default Re: Fluke 87 multimeter overload

I should have posted this video I did earlier. Fluke 25 is what you want for robust meter:

https://www.youtube.com/watch?v=eX4eme6c2S8
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Old 2nd Nov 2020, 12:12 am   #18
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Default Re: Fluke 87 multimeter overload

Quote:
Originally Posted by ajgriff View Post
Quote:
Originally Posted by Peter.N. View Post
The LCD display is beginning to degrade now but it still works perfectly.

Peter
Probably just needs the elastomeric (zebra) strip contacts cleaning.

Flukes really are the industry standard. There's no way I'd go back to using cheap DMMs.

Alan
The actual coating is coming off the glass but it hasn't progressed to the point that it is obliterating anything - yet!

Peter
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Old 2nd Nov 2020, 5:12 am   #19
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Default Re: Fluke 87 multimeter overload

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Originally Posted by Peter.N. View Post
The actual coating is coming off the glass but it hasn't progressed to the point that it is obliterating anything - yet!

Peter
On 70 seies meters there's a thin film of self-adhesive polarising sheet stuck to the glass. Without it the digit segments become invisible. The film can be peeled away completely and replaced.

Alan
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Old 3rd Nov 2020, 12:29 am   #20
Peter.N.
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Default Re: Fluke 87 multimeter overload

They are a bit newer than mine Alan.

Peter
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