Old FLUKE 8021B taken apart - Page 1
Forum section: electronics / general

author: johnmx
author_rank: Frequent Contributor
timestamp: November 11, 2010, 09:25:37 pm
content: Born almost 30 years ago and lived most of the time in a rough environment. It survived in my father’s workshop for so many years, thus for sure it’s good stuff.Now I just use it as a backup multimeter, however it’s still working very well.The first attached picture shows that it wasn’t treated very carefully all the time.In consideration to the EEVBLog community I’ve taken apart the 8021B and took some pictures of it (attached bellow)It lacks the auto power off feature but the continuity test beeper is the fastest I ever seen in this type of multimeter.The text on the bottom side of the PCB reveals the year of production (1981).I’ve never calibrated this multimeter and I will show you why.Measurements between the 8021B, a recent Fluke 115 and the 1905a multimeter from Thurlby Thandar Instruments (5½ digit resolution, ± 210000 counts):scale8021B1151905aV DC2V1.8961.8951.8951V DC20V7.007.007.0001V DC200V64.264.1664.220V AC750V218217.5218.0I DC2mA0.0660.000*0.0656I DC2mA1.9620.002*1.9658I DC20mA19.880.020*19.9511I DC200mA23.40.023*23.320I DC200mA198.70.198*198.358I DC2000mA110.011*10.85I DC2000mA19271.923*1927.92*2A ScaleResistence:scale8021B1151905ashorted2000.30.20.02325.5 / 0.1%20025.525.625.5041k78 / 0.1%2k1k7811k7801k7794010k / 0.1%20k10k0010k009k9982180k / 5%200k178k6179k4178k890820k / 5%2M829k831k828k7010M / 5%20M10M1310M1510M1005Well the numbers speak for themselves. Not a top multimeter, still not ready for retirementBest regards,johnmx

author: david77
author_rank: Frequent Contributor
timestamp: November 11, 2010, 09:57:17 pm
content: Nice one!You can see that integration has taken some big steps forward compared to my 8040.Btw. what causes the traces on the PCB to "bubble"?

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: November 11, 2010, 10:09:14 pm
content: I don't think the traces are "bubbled", that's just the solder mask that puckers up over time.

author: SG-1
author_rank: Regular Contributor
timestamp: November 12, 2010, 11:16:55 pm
content: I see the 9 volt battery connector has been replaced. The origional looked like a super thick piece of fish paper about the same colour as the meter, grey.I have a 8024A & had to replace the connector, or I would not know this...

author: SG-1
author_rank: Regular Contributor
timestamp: November 12, 2010, 11:42:29 pm
content: Here is a link to a Fluke article that covers some of the history.http://support.fluke.com/find-sales/download/asset/2386856_a_w.pdf

author: johnmx
author_rank: Frequent Contributor
timestamp: November 13, 2010, 12:55:23 am
content: Quote from: david77 on November 11, 2010, 09:57:17 pmIt’s not the solder mask, it’s actually the PCB traces. But it’s strange because if I press really hard on a bubble with a tip of a small screwdriver it doesn’t tear nor break.Quote from: SG-1 on November 12, 2010, 11:16:55 pmActually it’s the original. You can check that the solder joints are untouched.

author: JohnS_AZ
author_rank: Frequent Contributor
timestamp: November 13, 2010, 04:47:13 am
content: I just added this to the Wiki under Vintage testgear.You know, until I saw your photos I had forgotten that I owned one of those a long LONG time ago. It was a great meter.

author: SG-1
author_rank: Regular Contributor
timestamp: November 13, 2010, 04:51:38 am
content: Quote from: SG-1 on November 12, 2010, 11:16:55 pmActually it’s the original. You can check that the solder joints are untouched.My circuit board says 1980 & I am not the first owner. Mine could have been changed before I got my hands on it. The leads are discoloured (with age?) on mine & that is why I thought yours had been replaced. It shows the same bubbling on the circuit board.Here is a picture.

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: November 13, 2010, 06:22:27 am
content: Quote from: SG-1 on November 13, 2010, 04:51:38 amYour circuit board says 1981, and the bad news are that you are out of warrantyNever the less , this one are from the most hard to die models, and many of those are still alive, and in action even today.The Greek army has many of those.The PCB looks great , only the varnish looks to have issues due age.

author: SG-1
author_rank: Regular Contributor
timestamp: November 13, 2010, 07:33:19 am
content: Quote from: Kiriakos-GR on November 13, 2010, 06:22:27 amOut of warrenty for sure...My circuit boards do say 1980.

author: jahonen
author_rank: Super Contributor
timestamp: November 13, 2010, 08:54:37 am
content: Quote from: david77 on November 11, 2010, 09:57:17 pmI think that the board solder mask is not "SMOBC"-style (solder mask over bare copper), but older way where mask was printed over HASL or similar plating. When the board is wave soldered, this plating layer melts under the solder mask and it causes the traces to "bubble". It also makes it possible for solder during wave soldering to "suck" under the solder mask creating even bigger bubbles.Regards,Janne

author: Chad1
author_rank: Contributor
timestamp: November 13, 2010, 09:17:40 am
content: Ahhh neat! "Retro porn for engineers!" haha! It's stuff like this that get me excited and makes me absolutely sure that I'm in the correct field. Thanks for sharing! And how 'bout them there specs eh? Very cool! I love multimeters!!!!!!!!!!!!!!!!

author: Kiriakos-GR
author_rank: Super Contributor
timestamp: November 13, 2010, 06:17:16 pm
content: Quote from: SG-1 on November 13, 2010, 07:33:19 amYes , I got confused by the pictures above.

author: Ernie Milko
author_rank: Regular Contributor
timestamp: November 14, 2010, 07:06:47 pm
content: These are *SUPERB* meters. Stated accuracy is better the the 70-series that replaced them.