Need help for a Fluke 8520A Bench DMM

[Radiosmoker]

This is a letter and the response from Fluke.
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Response from Fluke:

Hello,

Unfortunately we are unable to help you with service here as this item is beyond repair support and we have no direct replacement plan. It was obsolete in 1996.

You can call our Fluke calibration support group at 877-355-3225 and ask to speak with the technical department.

Thank you,
Anne C.
Fluke Industrial Customer Service
888-993-5853

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My Letter:


To: Fluke Service Status
Subject: Repair or simple solution?



I have a Fluke that is Model# 8520A
When I first turn it on the display shows the normal 8520A

then shows IEEE – 01
then shows –.000 VDC

---Volts DC works on start

I have not used AC function

I have used nS in the past and at that time it worked

Then when I switch to the Ohms 2 wire it displays a random changing 4 0r 5 digit number with the word Ohm and the auto button is on.

I push the range up bottom and it continues random numbers starting at 5.123 for instance or such other random numbers after the 5 and counting in an upward directed count with the decimal positioned over the display 100 position.

I push the range button again and it goes to the 1000 position and continues its upward count at this point its reading 100.00 and still counting

I push the range button again and it goes to the 10 position and is still counting upward, at this point it shows 1.1360 KOhm and is till counting

I push the range button again and it goes to the 100 position and shows HH.HHH KOhm with the decimal flashing.

I push the range button again and it goes to the 10 position and shows . HHHHH MOhm with the decimal flashing.

I push the range button again and it goes to the 100 position and shows HH.HHH MOhm with the decimal flashing.

I then used a Resistor to test without pushing any buttons, the resistor is a 10Kohm (Brown, Black, orange, silver) and the display shows .011 Mohm.

I push the range button to go down and it changes the display to .01087 MOhm. with the decimal on the #1 position.

I push the range button to go down and it changes the display to 10.880 KOhm with the decimal on the #100 position.

I push the range button to go down and it changes the display to 10.8820 KOhm with the decimal on the #10 position.

I push the range button to go down and it changes the display to HHH.HH Ohm with the decimal on the #1000 position.

I push the range button to go down and it changes the display to HH.HHH Ohm with the decimal on the #100 position.

I push the range button to go down and it changes the display to H.HHHH Ohm with the decimal on the #10 position. And goes no further down.

Then start to go up in positions 10, 100, 1000, 10, 100 (at 100 I hear a Click.)

then I go up again and it goes to 1 and I hear a click again

then I go up again and it goes to 100 and I hear a click again and it stops at that point

I connect my resistor and the display shows .011 MOhm

sequencing Down again displays:

1- .01086 MOhm

100- 10.880 KOhm

10 Click- 10.8816 KOhm

1000- HHH.HH Ohm

100 faint beep- HH.HHH Ohm

10- H.HHHH Ohm

stops



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I don’t think this is normal.

After being on for at least 1 hour I can get readings but I have to fiddle with the range buttons.

When it works I can hear a relay every time I change resistor's or short the test leads.

The only thing I can think of is there are some wrong settings in Memory stack or others that I am not aware of.

I have used the % of change math OK

and the Zero test leads OK

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Do I need to Have this unit Repaired?

If so what would be the Cost?



(For Me at least, The manual isn’t that easy to follow. I have used the Reset button quite a few times. )

I have used math test 1

I have seen the display, tests OK



I know its out of warranty, but cannot afford and do not want to upgrade to a new Meter.

I don’t need calibration as my use is for my Hobby, I do have several multimeters but I like the feature of testing resistors on a pass/fail math function. By the way that math function does work.

What are your Thoughts?

Thank You

Cliff Jones
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To all who read this on ARF:
I could just cut my loses and abandon all Hope, but it may be just a simple fix.
The unit has a test sequence that I found and used.
Most tests passed, but with these exceptions:
I read the manual to find the error details, so here they are:
First number is actual reading I think, then Error number being FL09 I will underline display readings.

(Note I think the last two numbers are in tolerance max and min range of voltage in bold.)

+ .7798 FL09 1vac ZeroCHK
+.0498 -.010

next reading is FL10
+.0922 FL10 10Vac
+.0250 -.0100

next reading is FL13
+9.4911 FL13
1VAC gain +9.4871 -9.4437

it passes Digital PASS DTGL
Another forum mentioned Dust as a known culprit which I will look into later, that posting was several years old.
Any suggestions?

[Leigh]

That's a decent meter. I've worked on a few of them.

IIRC it has a memory backup battery ("coin cell"). That's probably gone dead, and you lost your cal info.

First suggestion would be to locate / replace that coin cell (with power applied).
That will preserve whatever cal data is still present.

- Leigh

[Radiosmoker]

I don't remember seeing any thing in the manual, but that I will definitely look for it. Thanks!
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This machine, for every math function that it has, is great. It has (for information for our other members reading this thread) it has IEEE-488 connector for remote control, being able to record extensive readings,
built in programs for :
-entering direct multimeter measurement data
- filtering
- common mode noise
- guard connection
- conduction to resistance measurements
- AC measurements
- DC measurements
- AC + DC measurements
- 2 wire resistance measurements
- 4 wire resistance measurements
- Conductance measurements
Burst v.s. trigger measurements
ASCII format
Its math functions are:

#1 TEST (four diagnostic self tests)

#2 ZERO (Automatic meter zeroing for lead and DC voltage offsets test)

#3 XREF (Ratio between input voltage reading and external reference voltage)

#4 OSR (subtracts offset from input, multiplies a scale factor, divides by a ratio value and displays)

#5 PCT (Displays the percentage of Deviation of input to stored normal value)

#6 PEAK (captures upper and lower Peaks and displays P-P value)

#7 LIM (Tests the reading against stored upper and lower limits, and displays the results of each reading, the number High, the number Low, the number that Pass, and the number of readings)

[MarkPalmer]

The 8520A was a condensed and less expensive version of the 8502/8505A lab meters. It is similar to the HP 3455/3456 meters just not as many math functions and one less digit of resolution. It didn’t use the motherboard/option module construction of the 8502/8505, and didn’t use software calibration memory (Thus no non-volatile or battery back-up memory.) It used conventional calibration via potentiometer adjustments. If you really like the 8520A, you’ll be able to find a working replacement on E-Bay much cheaper than anyone is going to be able to repair yours for you. They are about a $50.00-75.00 item.

-Mark-