Author Topic: Repair Fluke 87V  (Read 9390 times)

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Offline wizzer

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Repair Fluke 87V
« on: November 12, 2015, 05:03:44 am »
This is my first post....go easy on me  :)

I have a Fluke 87-V multimeter that I am trying to repair. When I select mV or Ohm, the screen shows four dashes on the screen. It also displays F87 on the screen when first powered on. All other functions work.

When I received the meter it had a broken LCD, the back metal shield was pressed up against the circuit board and the plastic RSOB housing had a crack. I replaced the LCD, bent the metal shield back and replaced the plastic RSOB housing. I had to move the RSOBs (metal contacts) to the new plastic housing. I thought maybe I screwed up the RSOB housing, but I tried one out of a working meter and there was no change.

Does anyone have any suggestions on what I should test or what the problem might be?

Thanks
 

Offline retiredcaps

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Re: Repair Fluke 87V
« Reply #1 on: November 12, 2015, 06:38:37 am »
1) Can we get a clear focused picture of the front pcb with the white rotary switch removed?
2) Can we get a clear focused close up picture of the front switch contact with the white rotary switch removed?
3) The 4 dashes problem has been seen before due to some pcb tracks being corroded.  See

http://mrmodemhead.com/blog/fluke-77-iv-copper-corrosion/
 

Offline Robomeds

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Re: Repair Fluke 87V
« Reply #2 on: November 12, 2015, 07:28:17 pm »
It looks like there are some water marks of some sort on the back of the metal shield.  That would suggest the PCB might be contaminated.
 

Offline Tim F

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Re: Repair Fluke 87V
« Reply #3 on: November 13, 2015, 02:26:16 am »
Yeah check the PCB contacts for the rotary switch. If you position the rotary switch between two working modes you'll see that it changes to the dashes. It's likely they are dirty or damaged and the meter is behaving as if there is no mode selected.
« Last Edit: November 13, 2015, 02:28:13 am by Tim F »
 

Offline wizzer

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Re: Repair Fluke 87V
« Reply #4 on: November 13, 2015, 06:03:10 am »
I have attached additional photos. I have also cleaned both sides of the board, including the contacts for the dial. When I slowly turn the dial, I am still unable to get the Mv and OHM function to appear.

I only see two spots on the back of the board that could be corrosion. I've tested the pathways and they tested ok.

Does anyone know what F87 when the meter power ups?

Any other ideas?

Thanks.
 

Offline TheSteve

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Re: Repair Fluke 87V
« Reply #5 on: November 13, 2015, 06:05:37 am »
The "F87" at power up just means it is a Fluke 87.
VE7FM
 

Offline tec5c

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Re: Repair Fluke 87V
« Reply #6 on: November 13, 2015, 06:33:41 am »
The "F87" at power up just means it is a Fluke 87.

+1

Is the pcb or dial warped in any way?

You need to break the fault location down further before finding the cause.

One idea would be to see if you can manually put the meter into ohms range without using the dial, i.e., short the appropriate tracks and see if the dashes still appear. If so then you should focus your attention on the pcb and eliminate the dial being the cause and vice versa.

 

Offline wizzer

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Re: Repair Fluke 87V
« Reply #7 on: November 13, 2015, 01:10:05 pm »
I had thought of manually shorting out the contacts to enable the Ohm function, but with four contacts on the dial it's a bit of a puzzle. I was hoping someone had a schematic or could identify which pads belong to which function. I'm almost positive the contacts on the dial are doing their job correctly so I don't think it's worth the effort to try and do it manually. Remember, I have tried a known working dial in the meter with no difference.

Thanks
 

Offline retiredcaps

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Re: Repair Fluke 87V
« Reply #8 on: November 14, 2015, 06:47:42 am »
When I received the meter it had a broken LCD, the back metal shield was pressed up against the circuit board and the plastic RSOB housing had a crack.
4) Was this meter dropped from a high height?
5) Was this Fluke 87V purchased from an authorized Fluke dealer?
6) Is the owner of this 87V the original owner/purchaser?
 

Offline tec5c

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Re: Repair Fluke 87V
« Reply #9 on: November 14, 2015, 09:42:49 am »
If you hold down the 'RANGE' button while turning the dial from off to Vdc you can put the meter into rotary switch (dial) test mode. A number should appear on the display. Rotate the dial through each function while verifying the values below.

All values have a tolerance of +- 12
Vac: 0
Vdc: -32
mVdc: -64
Ohms: -96
Diode: -128
mA/A: -160
uA: -192

Try this and let me know what values you get.

Edit: I believe this was only a feature for the first generation of 80 series meters and was not carried on to the V series.

« Last Edit: November 14, 2015, 09:58:47 am by tec5c »
 

Offline TiN

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Re: Repair Fluke 87V
« Reply #10 on: November 14, 2015, 09:46:30 am »
Mine just gives "5---" if turn it on with RANGE held. No matter how I rotate switch.  :-//
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Offline tec5c

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Re: Repair Fluke 87V
« Reply #11 on: November 14, 2015, 09:55:54 am »
Mine just gives "5---" if turn it on with RANGE held. No matter how I rotate switch.  :-//

"S---" is the smoothing feature. Which is used for when the input signal is fluctuating rapidly.

My bad. I believe this was a self test feature for the first generation of 80 series meters and was not carried on to the V series.
 

Offline ModemHead

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Re: Repair Fluke 87V
« Reply #12 on: November 14, 2015, 02:47:29 pm »
My bad. I believe this was a self test feature for the first generation of 80 series meters and was not carried on to the V series.
Yes the original 8x and 8x-III models had a "code switch" on  the back side that selected from a voltage divider chain, so that the switch position was voltage-level-encoded.  The self-test checks the divider and contacts.  The -V doesn't have that arrangement, so I presume that one of the contacts on the front is dedicated to switch position.
 

Offline wizzer

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Re: Repair Fluke 87V
« Reply #13 on: November 14, 2015, 08:19:25 pm »
4) Was this meter dropped from a high height?
5) Was this Fluke 87V purchased from an authorized Fluke dealer?
6) Is the owner of this 87V the original owner/purchaser?

The meter was part of a bulk equipment purchase. I have no idea how it was broken or where it was originally purchased from.

 

Offline retiredcaps

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Re: Repair Fluke 87V
« Reply #14 on: November 14, 2015, 10:30:40 pm »
The meter was part of a bulk equipment purchase. I have no idea how it was broken or where it was originally purchased from.
I asked because I wondered if you would qualify for Fluke's warranty repair service.
 


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