Author Topic: Old FLUKE 8021B taken apart  (Read 9596 times)

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Offline johnmx

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Old FLUKE 8021B taken apart
« on: November 11, 2010, 09:25:37 pm »
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) ;D

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):

  scale 
  8021B 
  115 
  1905a 
V DC
2V
  1.896  1.895  1.8951
V DC
20V
  7.00  7.00  7.0001
V DC
200V
  64.2  64.16  64.220
V AC
750V
  218  217.5  218.0
I DC
2mA
  0.066  0.000*  0.0656
I DC
2mA
  1.962  0.002*  1.9658
I DC
20mA
  19.88  0.020*  19.9511
I DC
200mA
  23.4  0.023*  23.320
I DC
200mA
  198.7  0.198*  198.358
I DC
2000mA
  11  0.011*  10.85
I DC
2000mA
  1927  1.923*  1927.92
*2A Scale

Resistence:
  scale 
  8021B 
  115 
  1905a 
shorted
200
  0.3  0.2  0.023
25.5 / 0.1%
200
  25.5  25.6  25.504
1k78 / 0.1%
2k
  1k781  1k780  1k77940
10k / 0.1%
20k
  10k00  10k00  9k9982
180k / 5%
200k
  178k6  179k4  178k890
820k / 5%
2M
  829k  831k  828k70
10M / 5%
20M
  10M13  10M15  10M1005

Well the numbers speak for themselves. Not a top multimeter, still not ready for retirement :)

Best regards,
johnmx
« Last Edit: November 11, 2010, 09:29:33 pm by johnmx »
Best regards,
johnmx
 

Offline david77

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Re: Old FLUKE 8021B taken apart
« Reply #1 on: November 11, 2010, 09:57:17 pm »
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"?
 

Offline JohnS_AZ

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Re: Old FLUKE 8021B taken apart
« Reply #2 on: November 11, 2010, 10:09:14 pm »
I don't think the traces are "bubbled", that's just the solder mask that puckers up over time.
I'm either at my bench, here, or on PokerStars.
 

Offline SG-1

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Re: Old FLUKE 8021B taken apart
« Reply #3 on: November 12, 2010, 11:16:55 pm »
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... 
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Offline SG-1

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Re: Old FLUKE 8021B taken apart
« Reply #4 on: November 12, 2010, 11:42:29 pm »
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
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Offline johnmx

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Re: Old FLUKE 8021B taken apart
« Reply #5 on: November 13, 2010, 12:55:23 am »
Btw. what causes the traces on the PCB to "bubble"?
It’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.

I see the 9 volt battery connector has been replaced.
Actually it’s the original. You can check that the solder joints are untouched.
Best regards,
johnmx
 

Offline JohnS_AZ

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Re: Old FLUKE 8021B taken apart
« Reply #6 on: November 13, 2010, 04:47:13 am »
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.
I'm either at my bench, here, or on PokerStars.
 

Offline SG-1

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Re: Old FLUKE 8021B taken apart
« Reply #7 on: November 13, 2010, 04:51:38 am »

I see the 9 volt battery connector has been replaced.
Actually it’s the original. You can check that the solder joints are untouched.
[/quote]

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.

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Offline Kiriakos-GR

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Re: Old FLUKE 8021B taken apart
« Reply #8 on: November 13, 2010, 06:22:27 am »

My circuit board says 1980 & I am not the first owner.

Your circuit board says 1981 , and the bad news are that you are out of warranty  ;D  ;D  ;D
Never 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.
« Last Edit: November 13, 2010, 06:25:38 am by Kiriakos-GR »
 

Offline SG-1

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Re: Old FLUKE 8021B taken apart
« Reply #9 on: November 13, 2010, 07:33:19 am »

My circuit board says 1980 & I am not the first owner.

Your circuit board says 1981 , and the bad news are that you are out of warranty  ;D  ;D  ;D
Never 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.

Out of warrenty for sure...
My circuit boards do say 1980.


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Offline jahonen

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Re: Old FLUKE 8021B taken apart
« Reply #10 on: November 13, 2010, 08:54:37 am »
Btw. what causes the traces on the PCB to "bubble"?

I 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
 

Offline Chad1

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Re: Old FLUKE 8021B taken apart
« Reply #11 on: November 13, 2010, 09:17:40 am »
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!!!!!!!!!!!!!!!!
 

Offline Kiriakos-GR

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Re: Old FLUKE 8021B taken apart
« Reply #12 on: November 13, 2010, 06:17:16 pm »
Out of warrenty for sure...
My circuit boards do say 1980.

Yes , I got confused by the pictures above.  :)
 

Offline Ernie Milko

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Re: Old FLUKE 8021B taken apart
« Reply #13 on: November 14, 2010, 07:06:47 pm »
These are *SUPERB* meters. Stated accuracy is better the the 70-series that replaced them.
 


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