Fluke 8020B Teardown - 30yo DMM Technology

[ModemHead]

Thanks to a tip from EEVBlog forum member retiredcaps, I recently picked up a Fluke 8020B DMM for $5 + postage from the usual auction site. This model dates from somewhere in the early to mid-80s and is an updated version of the 8020A, Fluke's first handheld DMM. The seller's description said this one "would not power up". However, when I installed a battery, it worked perfectly. Overall, the unit is in very good cosmetic shape, especially after a thorough cleaning. Unfortunately the button for the AC/DC selector switch is missing.

So for those who may be interested in 30 year-old DMM technology, let's take it apart!


The case is held together by 3 self-tapping screws. I deem myself qualified to remove the screws.


Accessible (barely) from the battery compartment is a 2A glass fuse, with a spare thoughtfully provided in a plastic clip. The battery cover fits tightly and is a major pain to remove and re-install.


Flexible shielding material wraps around most of the circuit board assembly, bonded by a small screw to a metal stand-off. The shield is permanently attached to the case bottom half with melted-over plastic studs. The 3A HRC fuse is not accessible until the meter is disassembled to this point. Also accessible is a DC cal adjustment, AC cal adjustment, and a "high-frequency" compensation adjustment. The meter is spec'ed to 5KHz bandwidth with reduced accuracy from 1kHz to 5kHz.


The circuit board layout is dominated by the push-button switches. The daughter board on the right contains the continuity beeper circuitry and piezo noisemaker. The fuse block is quite firmly attached at that angle.


Double-sided board. All through-hole components. Wrinkly solder mask, which is common for PCBs of this era. The PCB artwork is dated 1981.


The LM358 op-amp on the main board is the AC converter and is factory-selected for 600kHz GBW. The continuity piezo noisemaker is on the little daughter board, triggered by an LF442 op-amp comparator and a 74C00 quad nand gate as oscillator and driver. The JFET-input LF442 is selected for 100pA input bias current. The continuity buzzer is supposed to be used with the 2K-ohm range which results in a 115-ohm threshold. But since the buzzer is driven by a comparator from the voltage divider, the buzzer also operates in other resistance ranges at non-useful thresholds.


The 3A fiber tube HRC fuse is in series with the 2A glass fuse, providing 10kA interrupting capability in case of a serious fault. Series varistors, a thermistor(obscured) and a 1K 2W fusible resistor provide over-voltage protection. The two beefy 2A diodes limit voltage across the current measurement shunt.


All through-hole components, no SMD in sight. The large gray-black tapped resistor is the current shunt for measuring up to 2A. The blue resistor network behind it is the primary voltage divider. The input thermistor is fully visible in this shot beside the 1W 100K resistor.


External power input jack is under the display. Not usually found on modern DMMs due to the safety hazard. The power rails are not isolated from the meter's input jacks, and thus could raise the 9V input to hazardous voltages.


The 4030 quad exclusive-OR gate is used to drive the LCD decimal points and lo-bat annunciator, gated with the LCD backplane clock. The rectangular orange components are resistor arrays.


Those are some sturdy-looking switches.  They consume a lot of space, but there are no extra components hidden underneath.


This meter is 3-1/2 digit, 2000-count. The display is a fairly generic "1888" with decimal points, leading minus sign and a "BT" low-battery annunciator.  There are no bar graphs or units indication.


The black elastomeric connector is tall and thin and held in place with a removeable plastic piece.  The protective transparent lens is 2.4mm thick Perspex.


The A/D converter/LCD driver is a 40-pin DIP Intersil chip marked with Fluke p/n 429100. Probably very similar to the ubiquitous ICL7106. Looks like a 1985 date code. The device in the TO-18 metal case below the trim-pot in the upper left is a 1.22V bandgap voltage reference. The clock crystal is 3.2MHz.


Measuring an 806-ohm 0.25% precision resistor mounted on a dual banana plug. The tilt stand is a bit short, but the display is already angled, so the net result is a good viewing angle. Note the external power jack at top right.


Measuring a 5.000V reference voltage. I never touched the trim-pots. It arrived this way. Not knowing this unit's history, I have no idea if it was ever in a calibration program. But in any case it's still perfectly useable.


Thanks for looking.

Edit 1-July-2017: Photobucket sucks.

[robrenz]

Nice review, great pictures

[Amarbir[Lynx-India]]

Well,
    beautiful mind blowing review  ,just curious how old is the hrc fuse technology is btw

[robrenz]

@ Amarbir 

This is the kind of review I am talking about in your meter thread.  Great pictures, Lots of detail, Nothing left out, some basic accuracy checks, good commentary.

[david77]

Very nice tear down, lovely photos.

Have been looking for a 8060 for some time, I like these old Fluke meters.
Just one thing: It is not Flukes first hand held DMM, they introduced the 8030 and the 8040 in about 1974. Very different technology and form factor but hand held and portable none the less.

[saturation]

Nice, very good restore job.  You could easily get another one on eBay and cannibalize a keycap.  This model made Fluke famous for DMMs back in the late 1970s.  It set a trend for a style that was heavily copied.  I lusted after that and could only afford a kit copy, and it doesn't look half as good as the 8020a 30+ years later, but its still calibrated [ one feature was it was manually self calibrating] and working.

http://www.fluke.com/Fluke/usen/community/fluke-news-plus/ArticleCategories/RD/25-Years+of+DMMs.htm

A pdf history of the Fluke DMM:

http://support.fluke.com/find-sales/download/asset/2386856_a_w.pdf

[Excavatoree]

Unfortunately the button for the AC/DC selector switch is missing.

PM or e-mail me your address - I'll send you one that, hopefully, will be up to the rest of the meter's appearance.

I've got several of these, most are in pretty bad shape, but many of them still work and still meet specs.

I don't have any in that nice of a condition.

[ModemHead]

Nice, very good restore job.  You could easily get another one on eBay and cannibalize a keycap.  This model made Fluke famous for DMMs back in the late 1970s.  It set a trend for a style that was heavily copied.  I lusted after that and could only afford a kit copy, and it doesn't look half as good as the 8020a 30+ years later, but its still calibrated [ one feature was it was manually self calibrating] and working.

As for restoration, I didn't do much but clean off some grime. It worked right off the bat. Even the fuses are good. I think this unit had an easy life somewhere, it obviously has not been abused. I was only a little disappointed that I missed the opportunity to fix it or go off in search of something made of unobtainium.

When this unit was new, I was a junior engineer who got assigned the beat-up old Simpson 260. The senior engineers got the new stuff.  So it's fun for me to get this so cheaply and play with it. And share the pix.

[ModemHead]

Unfortunately the button for the AC/DC selector switch is missing.

PM or e-mail me your address - I'll send you one that, hopefully, will be up to the rest of the meter's appearance.
...

Thanks! That's very kind of you.

[retiredcaps]

Have been looking for a 8060 for some time, I like these old Fluke meters.

Initally, I alerted ModemHead with this auction, but was too slow in typing

http://www.ebay.com/itm/130773179911

$6 for a potentially working 8060A with a faded lcd.  From what I read, the old Fluke 8060a has insanely wide AC bandwidth (100kHz for some ranges)

Even if it didn't work, I would pay $6 for it because the manual has full schematics and with all through hole components I might have a decent chance of learning a lot.

[EEVblog]

Great photos!
The ducks guts of old Flukes is the 8060A. Still has potent specs by today's standards.

Dave.

[firewalker]

30 years old and still safer than many new DMMs...

Alexander.

[EEVblog]

Heads up:
Fluke 27 in awesome nick for $40:
http://www.ebay.com.au/itm/280984986629?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_5707wt_1397
2 available.

Dave.

[Salas]

Make cheap or make proper is older policy than merely 30 yrs old.

[ejeffrey]

I know a lot of people who still swear by these things.  Particularly if you need manual ranging these meters can be operated one handed and are much nicer than the typical rotary switch with 20 positions.

[Flávio V]

Might teardown my 8060A to show...i have recently fixed the battery connector so it is not 100% original...

[saturation]

That's a great buy.  Older Fluke's had an issue with debris collecting under the elastomer of the LCD, all it needs is a cleaning and it likely will work as good as new.  Many old Flukes make great lab and home DMM; they are all pre-CAT rating, do not have built in transient protection and if used in a professional setting could incur some liability.

Have been looking for a 8060 for some time, I like these old Fluke meters.

Initally, I alerted ModemHead with this auction, but was too slow in typing

http://www.ebay.com/itm/130773179911

$6 for a potentially working 8060A with a faded lcd.  From what I read, the old Fluke 8060a has insanely wide AC bandwidth (100kHz for some ranges)

Even if it didn't work, I would pay $6 for it because the manual has full schematics and with all through hole components I might have a decent chance of learning a lot.

[david77]

Thanks for the heads-up, but shipping costs from the US are insane. I'll wait until one shows up here in Europe. It's not something I need urgently, just one piece of kit I'd like to have.

Have been looking for a 8060 for some time, I like these old Fluke meters.

Initally, I alerted ModemHead with this auction, but was too slow in typing

http://www.ebay.com/itm/130773179911

$6 for a potentially working 8060A with a faded lcd.  From what I read, the old Fluke 8060a has insanely wide AC bandwidth (100kHz for some ranges)

Even if it didn't work, I would pay $6 for it because the manual has full schematics and with all through hole components I might have a decent chance of learning a lot.

[lowimpedance]

 Nice clear full detail pics., and in nice condition -  good score.
The main chip is indeed an Icl7106!. I own 2 8020A 's which had stuffed LCD's so I 'hard wired' repaired them with modern displays easily and cheaply available. A small amount of fitting mechanically and the meter is good to go. The thread is in the blogs archives under Fluke 8020a with bad LCD.
low Z

[amyk]

Does anyone else find it interesting that Fluke used the same ADC chip that's now found in the cheapest Chinese DT-830 series DMMs?

[saturation]

It was state of the art at the time, DMMs that flooded the market thereafter in the early 1980s used the same chip, how the chip has survived in panel meters today and such is a testament to good chip design.  Note the 8020 is occupied mostly by the switch assembly rather than electronics; the 7106 made it possible to make DMMs affordable to most everyone.

[ModemHead]

Yes, it's very interesting that my 30 year old $5 meter shares the same basic technology as today's $5 Harbor Fright meter.  A testament to good chip design, but the fact that this one is still here and working is also a testament to good solid product design.  I'm not so sure anything made today will still be around in 30 years.

@low-Z: That was a great thread! I learned about removing the polarizing film from an LCD there, plus the inspiration from seeing someone hack old equipment back into use.

[saturation]

Yes, they are made very well, while there are a few DMMs from that era are also good, they are not as prolific as Fluke from top brands: HP had a few DMMs as well as Tek.  Functionality and practical accuracy came out of the 1980-1990 period pretty much based on Fluke's models, while HP set the standard for bench DMMs.  By 1987, the Fluke 80 series came into the catalog and has been there ever since, and what's new with different generations are higher IC integration, CAT and Pollution rating, increase toughness and IP ratings, but the accuracy ratings, design and features  [ capacitance, frequency counter etc.,] are unchanged.  Can the Chinese or lesser brand DMMs, endure?  They probably can but a typical Fluke is made to survive desert heat, Alaskan cold, humidity of a seagoing vessel, military applications helped its reputation. The original Fluke's weren't IP or Pollution Degree rated but they empirically survived and created its reputation.  So for home labs and consumers, this level of toughness is overkill, but if you can get a used Fluke DMM cheap on eBay, its most likely will last a lifetime compared to a newer meter from lesser brands because Fluke has a legacy, while the other's still have to make theirs.

Yes, it's very interesting that my 30 year old $5 meter shares the same basic technology as today's $5 Harbor Fright meter.  A testament to good chip design, but the fact that this one is still here and working is also a testament to good solid product design.  I'm not so sure anything made today will still be around in 30 years.

@low-Z: That was a great thread! I learned about removing the polarizing film from an LCD there, plus the inspiration from seeing someone hack old equipment back into use.

[free_electron]

Don't diss the 'lowly 7106. The technology in that device is still the most accurate way of measuring a voltage as it is completely self adjusting and self-nulling. These machines are a voltage to time-interval converter ( and not an 'ADC' like we know it in the traditional sense like a SAR or a thermometer system ). The conversion mechanism is dual slope. Even the Agilent 3458 8 1/2 digit machine uses that technique. that's how accurate it can be made.
Can't get there with any other known a/d convertor technique.

The fluke parts are probably a bit 'selected'.

my first digital multimeter ( 1984) was a hung-chang clone of the 8020 .

[SeanB]

7106 only has a few needs for accuracy. A short term stable clock, it only has to be stable over under 5000 cycles, nothing more. A reference voltage of the desired accuracy, and you have a built in one good enough for room temp operation right on the chip, which will give accuracy of 199x at least. You need one good film capacitor to store charge, and all it needs is low leakage and no voltage dependance, easily met by most modern polyester film units.

Not terribly sensitive to supply voltage. Can work with a lot of noise on the input, and if you select the clock right it ignores mains hum completely. Very god for ratiometric use, which can be done totally without any trim at all needed if you use precision resistors. Robust device as well, and easy to interface to the LCD displays.

[LaurenceW]

Nice picture, Modemhead. Nostalgia is not what it used to be, eh?

[Bored@Work]

I just wounder what the deal between Fluke and Intersil was. Fluke claims they designed the IC. And we know Intersil manufactures it, even back then.

If Fluke designed it, they must have agreed to Intersil marketing it under their own name, too. Maybe Intersil was allowed to keep the floor sweeps?

[free_electron]

7106 only has a few needs for accuracy. A short term stable clock, it only has to be stable over under 5000 cycles, nothing more.

correct. the rampup cycle is 2000 counts with the rampdown a maximum of 2000 counts. throw some additional steps in there to do a null check and you end up at about 5k cycles.

You need one good film capacitor to store charge, and all it needs is low leakage and no voltage dependance, easily met by most modern polyester film units.

low leakage and soakage and low tempco is what you are after. pyloester film performs fine. silver-mica if you want it really right.

[SeanB]

Nice is that the chips are now made by many manufacturers, and are pretty much the same performance wise. The original design has held up well, you get improved parts, but they are backwards compatible with the original. Nice is that you can get a 7106 variant that has a full scale of 20mV and is stable at that, the originals did 200mV.

[Rick]

Fluke 27 in awesome nick for $40:
http://www.ebay.com.au/itm/280984986629?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649#ht_5707wt_1397
2 available.

I missed that one.
So I contacted the seller to ask if he had more and he had used ones. The one mentioned by Dave being a "new one without box" obviously it was used very little.
The ones (2) I bought do not have very "sharp" looking displays (they are not delivered yet but I have seen the pics) so may be should I clean the contacts or replace the display ? I wonder if Fluke would sell spare parts such as LCD displays, elastomers and the glass on top of the LCD.
It was not a good bargain either because I got them for the same price as the "new" one.

I beware when a pic shows the meter turned off, like recently a guy from the middle east has told me the DMM works fine (a Fluke 8021b) but it has no battery, so I told him "buy a battery and show me the pic of it and I shall pay you the price of the battery too". But there is no answer yet...   
As it is an international shipment they know you wouldn't send the item back as it is a low cost item.
 

[ModemHead]

Great discussion on the venerable 7106. I am inspired to read up on how it really works.  And thanks to Excavatoree, my 8020B is no longer missing a button and is ready for service again!

[T4P]

Cyrustek themself has a ICL7106 drop in replacement 
http://www.datasheetcatalog.org/datasheet/CyrustekCo/mXrvszy.pdf
Found it on my wavetek DM5XL

[Lawsen]

I used to own a Fluke 8060A, before it broke.  The microprocessor counting display chip needs replacement.  Fluke exchanged it for a Fluke 187.  A Fluke 8060A was sold for $425.00 new in 1989.  My Fluke 8060A stopped working by 2000 and Fluke simply exchanged it for a Fluke 187.  Thanks for posting the Fluke 8020B.  There was also a black color version of the Fluke 8024A.  I did not see much of them.  Surf here for the Fluke 8024A manual.  The old Fluke 8060A came with two manuals, a self service manual with all the parts listed and where to buy them and detailed mechanical and schematic circuit and probing tips and a general users manual.  Hardly any electronics company in the world still practices this much detail.  Fluke 187 multimeter that was exchanged did not has a service manual and the users manual was not much, just simple pictures in different languages, but no details or any use.  I wondered, maybe, I should have repaired the Fluke 8060A myself at the studio than send it in only to be e wasted and traded in.  The bench top equivalent to the Fluke 8060A is the Fluke 8050A and it came with quite a detailed manual in service and using, too.  These are truly classics, both instrument and documentation, never again by Fluke.

http://www.ko4bb.com/Manuals/Fluke/Misc/8024A_Manual.pdf

[rsjsouza]

And thanks to Excavatoree, my 8020B is no longer missing a button and is ready for service again!

Sorry for revamping an old thread, but I too would like to publicly thank Excavatoree for sending me two button caps for a recently purchased Fluke 8060A!

[YashEE]

I know that I'm rather late to this Post. The pix are a nostalgic delight and are inviting this question:

I have since new (ca. 1979) 8020A model that I managed last week (!) to damage (voltage spike) the input section (over voltage protection portion)  - blowing the R2 (1000 ohm /2 watt) resistor and two of the 430V varistors (RV1 and RV2).

Is there a parts source to get the 'original components' or what would you good folks recommend an appropriate replacement of same

(btw, I replaced the 1K 2W resistor with a 1% metal oxide type -not fusible type as in 8020B)   

[Excavatoree]

The 1K 2W fuseable resistors are getting difficult to find.  There was a replacement I used to purchase from Digi-key, but it was discontinued.  Modemhead mentioned one, it may be available in Canada, but it wasn't available on the US site when I checked.  I wish I had ordered more of them - I'm out myself and all my parts meters have had them removed.

Parts availability may depend on your location.  Where in the world are you?

[MarkPalmer]

Factory new parts should still be available from Fluke themselves, Tucker Electronics or Talon Electronics using the Fluke part numbers.  474080 for the 2W resistor, 447672 for the varistors, both varistors are the same.  But.....

You can probably buy a used 8020A for use or one to scab the parts from for much less than what it will cost to buy new factory parts.  If it's sentimental I understand, I still have my 8020A I bought brand new in 1983.   

-Mark-

[YashEE]

Thanks for such a quick replay -I am in the Philadelphia area...

The fried R2  1000 +/- 10% resistor was not fusible as such (not sure I can tell) so I simply replaced it with a metal oxide 2W type (1%).   

The varistors (430V type) are cylindrical / vertically mounted -need at least two of those or recommended replacement   

[Excavatoree]

I'll check my "junkyard."

[retiredcaps]

The 1K 2W fuseable resistors are getting difficult to find.

The Fluke 8020A manual just says

R2, ww, 1k +/-10%, 2W

Nothing about it being fusible. edit: However the part number for the A and B are identical.

PS. If you need 1K 2W fusible resistors, modemhead got his latest batch from Moyer (part number F2W210)

http://www.moyerelectronics.com/BVModules/ProductTemplates/MoyerProductTemp/Product.aspx?productid=37a1f44f-b860-407d-93b6-a7601a4423d8

NTE Fusible Power Oxide Resistor 2W 1K OHM 5% Fuse.  Data sheet at

http://www.nteinc.com/resistor_web/pdf/1w_2w_fusible.pdf

Shipping, iirc, was a very reasonable $2.50 ish using USPS first class mail for USA customers?

I got 10 even though I personally have never subjected my meters to abuse, but the ones I buy used sometimes requires a replacement fusible resistor.

[Excavatoree]

The 1K 2W fuseable resistors are getting difficult to find.

The Fluke 8020A manual just says

R2, ww, 1k +/-10%, 2W

Nothing about it being fusible.

PS. If you need 1K 2W fusible resistors, modemhead got his latest batch from Moyer (part number F2W210)

http://www.moyerelectronics.com/BVModules/ProductTemplates/MoyerProductTemp/Product.aspx?productid=37a1f44f-b860-407d-93b6-a7601a4423d8

NTE Fusible Power Oxide Resistor 2W 1K OHM 5% Fuse

Shipping, iirc, was a very reasonable $2.50 ish using USPS first class mail for USA customers?

I got 10 even though I personally have never subjected my meters to abuse, but the ones I buy used sometimes requires a replacement fusible resistor.

Thanks for the info.  I  suppose when I saw the older 70 series meters with the same resistor as the 80xx series, I just assumed they were fuse resistors as well because the replacements were.   I know better, but I still do it.

[retiredcaps]

I  suppose when I saw the older 70 series meters with the same resistor as the 80xx series, I just assumed they were fuse resistors as well because the replacements were.

Just to make it more confusing, the 8020B, which is what this thread is based on, does say in the manual, the word "fusible" for R2. 

[retiredcaps]

The varistors (430V type) are cylindrical / vertically mounted -need at least two of those or recommended replacement   

Looking at "my always open" 8020A, there seems to be enough room to use the radial disc varistors (if I'm using the correct terminology)?

For example, this random one that I chose at digikey

http://www.digikey.com/product-detail/en/ERZ-V05D431/P7245-ND/162591

is 430V and 5mm.

[MarkPalmer]

The resistor was the same fusible one in both the 8020A and 8020B, part number 474080.

-Mark-

[retiredcaps]

The fried R2  1000 +/- 10% resistor was not fusible as such (not sure I can tell) so I simply replaced it with a metal oxide 2W type (1%).   

reply from drtaylor

https://www.eevblog.com/forum/testgear/old-fluke-multimeters/msg515471/#msg515471

Now you see what I mean about information spread all over the place...

[retiredcaps]

The resistor was the same fusible one in both the 8020A and 8020B, part number 474080.

Yes, you are correct.

In looking how I made that error  , I see the Fluke 8020B manual at

http://exodus.poly.edu/~kurt/manuals/manuals/Fluke/FLUKE%208020B%20Instruction.pdf

has the BOM sideways and the 8020A manual at

http://exodus.poly.edu/~kurt/manuals/manuals/Fluke/FLUKE%208020A%20Instruction.pdf

has the BOM vertical.

While looking at the 8020B sideways BOM, the part number is not in the screen so I didn't notice they were the same part number.  I will correct my posts above to reflect this.

[Excavatoree]

Thanks for such a quick replay -I am in the Philadelphia area...

The fried R2  1000 +/- 10% resistor was not fusible as such (not sure I can tell) so I simply replaced it with a metal oxide 2W type (1%).   

The varistors (430V type) are cylindrical / vertically mounted -need at least two of those or recommended replacement   

PM sent - hopefully these parts can remain  useful by allowing another 8020 to keep running.

[drtaylor]

Just for the record... This excellent tear down by ModemHead had one misleading comment ("Probably very similar to the ubiquitous ICL7106"). The 429100 is NOT the same as a ICL7106 (though it is indeed similar). The Fluke part was the basis for the ICL7106, but the 7106 lacks one key feature. The 429100 chip can digitally switch between a 200mVFS and 2VFS range. The ICL7106 requires part changes to accomplish the same thing. I wrote more on this topic in the forum subject titled "Old Fluke Multimeters."

If you sub an ICL7106 into a Fluke 802x series DMM, it will not work properly.

I have a small stock of 429100 chips if anyone needs one. They have been in antistatic foam for >30 years, so I don't know if they function. I could try them in one of my vintage Flukes to see if they're still functional.

[YashEE]

Thanks to Excavatoree, the 8020 lives / works again...most generous to send a full complement of original 430V veristors including the classic R2 befitting the ca. 1979 DMM. Had some pangs of nostalgia and trepidations replacing the fried components but all went well and functioning as per specs (!)

Much appreciated advice from the Board.
 

[lowimpedance]

Just for the record... This excellent tear down by ModemHead had one misleading comment ("Probably very similar to the ubiquitous ICL7106"). The 429100 is NOT the same as a ICL7106 (though it is indeed similar). The Fluke part was the basis for the ICL7106, but the 7106 lacks one key feature. The 429100 chip can digitally switch between a 200mVFS and 2VFS range. The ICL7106 requires part changes to accomplish the same thing. I wrote more on this topic in the forum subject titled "Old Fluke Multimeters."

If you sub an ICL7106 into a Fluke 802x series DMM, it will not work properly.

I have a small stock of 429100 chips if anyone needs one. They have been in antistatic foam for >30 years, so I don't know if they function. I could try them in one of my vintage Flukes to see if they're still functional.

 I think many including me had just assumed it was just a 7106 but thanks to you we know its not a substitute. From my perspective having come across quite a number of meters employing this IC , not one of them needed that part replaced, so its quite a reliable component.
I wonder just how many have had to replace one ? not many I'll bet.

[SeanB]

Only time I replaced them was due to them getting blown up, either from supply voltage faults or from massive input overloads.

[MarkPalmer]

Excellent review!  Here is my faithful 8020A I bought in '83 being checked against calibrator.  Short of a few new batteries, the internals have never been touched.  This model was not Fluke's first portable, but it was their first handheld DMM.  The series was imitated by many, but it took a long time to be matched in quality or performance by anyone else in its day. 

-Mark-



-Mark-

[leppie]

These old meters really have no cal/drift issues. Recently picked up a Fluke 867B and it was one count (4.5 32k count) out from my Chinese 2.5-10V reference. The cal date is Oct 2000, and looking at the cal report, the numbers are still within what the cal report says  O0

[sibeen]

I'm in to report a sad, sad tale.  I was noodling around the site tonight and noticed a thread about cheapish Keysight U1252B. My venerable old 8050B, in my possession since about '89 has been playing up a bit. I've finally *sob* decided to put her down. I shamelessly went and ordered two of the 52Bs. I haven't told her yet. I'll need to drink rather heavily before I can face up to that conversation.

[drtaylor]

Does anyone else find it interesting that Fluke used the same ADC chip that's now found in the cheapest Chinese DT-830 series DMMs?

As stated in some of my earlier posts, the 429100 chip is not the same as the ICL7106. In fact, Intersil took the Fluke design, removed a feature, and then marketed it. The original 8020 chip was defined and designed by a joint team of Fluke engineers and Intersil engineers. The main difference is the 429100 chip has two voltage ranges, 200mV and 2V. It switches these internally. You cannot put a ICL7106 in any variety of Fluke designs and have it work properly.

The difference between the 8020A and the 8020B is the addition of the small board that has a continuity piezo beeper. No other significant improvements.

BTW I have a small inventory of 429100 chips if anyone needs one. For more information about the 8020 design and my 8060 design, please visit the Old Fluke Multimeters topic.

[saturation]

Given how the 7106 made low cost DMM and panel meters easily made Fluke can be seen as a major force for most modern DMM or LED/LCD panel meters.

Does anyone else find it interesting that Fluke used the same ADC chip that's now found in the cheapest Chinese DT-830 series DMMs?

As stated in some of my earlier posts, the 429100 chip is not the same as the ICL7106. In fact, Intersil took the Fluke design, removed a feature, and then marketed it. The original 8020 chip was defined and designed by a joint team of Fluke engineers and Intersil engineers. The main difference is the 429100 chip has two voltage ranges, 200mV and 2V. It switches these internally. You cannot put a ICL7106 in any variety of Fluke designs and have it work properly.

The difference between the 8020A and the 8020B is the addition of the small board that has a continuity piezo beeper. No other significant improvements.

BTW I have a small inventory of 429100 chips if anyone needs one. For more information about the 8020 design and my 8060 design, please visit the Old Fluke Multimeters topic.

[karlo]

My Fluke 8020B display has gone all black. Is it still possible to get an LCD display for this model? 

[Fungus]

My Fluke 8020B display has gone all black.

It's a common problem in those meters. John Fluke refused to use any Japanese parts in the meter and it turned out the USA-made LCDs weren't very durable.

Is it still possible to get an LCD display for this model?

Two options:
a) Buy a broken meter with a good screen (not easy - the screen is usually the first thing to go)
b) https://www.sbprojects.net/repair/fluke8020a/index.php

[frozenfrogz]

Or you could go all the way down the rabbit hole and try an LED conversion like http://mrmodemhead.com/blog/a-very-unique-fluke-8060a/

[rsjsouza]

The resident "Fluke Jedimaster" mr modemhead published another repair procedure at:
http://mrmodemhead.com/blog/fluke-8020a-lcd-replacement/

I followed it to repair my dad's 8020A.

[AGANTE2011]

Good morning,
I´ve 3 multimeters Fluke 8020B and 2 of them has the same problem, the voltage reading in all scales of DC and AC is floating a lot and doesn´t match with the real voltage applied in the probes. I already replaced the A/D Intersil 429100 by new one in both equipments and the problem was not solved. Before start a more deep troubleshooting anyone had this problem or have any idea to solve?  Many thanks in advance for support. AGANTE2011

[frozenfrogz]

Welcome to the forums

I would start with checking the electrolytic caps. Everything else is pretty robust.

[drtaylor]

I already replaced the A/D Intersil 429100 by new one in both equipments and the problem was not solved.

Please be aware that the 429100 chips are not the same as Intersil ICL7106. Only a Fluke actual 429100 (but it is made by Intersil) will fully function on all ranges. As already suggested, the most likely problem would be old Electrolytic caps, and circuit board contamination caused by them.