Fluke 8020B Teardown - 30yo DMM Technology

[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.