Author Topic: Advantest R6581 8.5 digit DMM mini teardown/repair  (Read 58715 times)

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Offline branadic

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #600 on: August 27, 2019, 11:54:05 am »
Don't get me wrong Kleinstein, but beside the turn over issue there is no INL issue. It's more like there is a gain error present, that results in a negative slope over the entire 10V range, thus +10V /= -10V.

-branadic-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 

Online Dr. Frank

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #601 on: August 27, 2019, 12:01:44 pm »
Hi branadic,
haven't you calibrated the 4000As gain yet?
Frank
 

Offline branadic

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #602 on: August 27, 2019, 04:02:25 pm »
Frank, it's not a gain issue of the Datron 4000A, but a gain issue of the R6581D, if gain is the correct word for it. You can clearly see that, as K3458A shows that Datron 4000A produces the correct output voltage. Both meters were in parallel to the Datron 4000A.

-branadic-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 

Online Kleinstein

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #603 on: August 27, 2019, 04:48:04 pm »
The calibration of the 6581 seems to be off a little (e.g. some 5 ppm) compared to the other instruments.

For most of the part the linearity looks good. The range from 0 to about -2 V and especially the jump near zero is probably the worst part of it. For the U³ part it looks like that much of the error is due to the calibrator, as the curves look similar for both meters. Still there is a little difference.
However the curve does not look like there should be a lot of turn over error.
 

Offline branadic

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #604 on: August 27, 2019, 05:29:51 pm »
Kleinstein, no calibration is not off, it was freshley calibrated at 0V and +10V comparing a 10V reference to the K3458A (artifact calibration), however -10V doesn't fit and therefor the slope in the deviation plot. To make it more clear, the plot of deviation [V] is meter reading - set voltage. The resulting slope from +10V to -10V is exactly my issue and I have no idea how to get rid of that.

-branadic-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 

Online Kleinstein

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #605 on: August 27, 2019, 06:08:18 pm »
Is the zero offset OK ? The first curve for the 6581 looks like there may be quite some error at 0 V.

The deviation plot also has a slope for the positive side, so the error is no just for the negative side.
A turn over error suggests that the positive and negative behave different. However the curve does not look that asymmetric. Still it is hard to judge how much is from the calibrator and how much from the meter(s).

A possible problem could be from fast versus slow measurements. Thermal effects could take some time and thus behave different for just a zero reading and the zero reading as part of the AZ cycle. So there could be some settling effects, that might effect the calibration measurement. An error in the zero (e.g. thermal EMF from the relay) could also be a factor if rather large. This could improve with the relay fix, especially if the internal correction for the offset is somewhat handled the wrong way during calibration.
 

Offline branadic

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #606 on: August 28, 2019, 05:53:44 am »
I think I had a temperature issue and temperature changed over time, since the measurement was done with NPLC100, 10 values per voltage step and 20s delay time between each voltage step for the calibrator to stabelize and from +11V to -11V.
I will repeat this measurements with NPLC20, only 5 values per step, 10s of delay between each step and an alternating voltage step strategy, which means +0V, -0V, -100mV, +100mV and so on. This way I should get similar results for both, positive and negative values without temperature variations effecting the measurement to much and since the Datron 4000A switches output polarity only results will become better, hopefully.

-branadic-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 

Offline e61_phil

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #607 on: August 28, 2019, 06:06:20 am »
20s seems a bit short to me. My Fluke 5440B takes much longer to get very stable. For the first experiments I took measurements with the 3458A and I did that until three succeeding 3458A measurements are within a given range.

If you want to test transfer accuracy it might be better (or another experiment) to jump between 0, 1V and 10V with some random numbers on top. Such a meausrement is done in a couple of minutes and don't need ultra stable temperature enviroment. And the result is more meaningful than these nice looking, but not much saying INL curves. They are nice for comparisions, but for absolute numbers to calc with, I prefer the steps.
 

Online Kleinstein

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #608 on: August 28, 2019, 07:58:56 pm »
To reduce the temperature effect and make is visible one should run the same points several (e.g. 5 x) times. This may require a shorter measurement (may not be that practical as the settling time can be significant) or less points. (e.g. 0.25 V steps and fine steps only for a smaller range, possibly as a separate run).
 

Offline branadic

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #609 on: September 03, 2019, 07:53:34 pm »
Finalized my binding post mod. The adapter is 3D printed and designed to match the LowThermal binding posts. It looks like Advantest initially planed to install this higher quality posts, but decided for the brittle plastic solution instead. It's still no 3458A, but definitely higher grade now and I like it.  :-+

-branadic-

EDIT: Attached are the CAD files for the adapter.
« Last Edit: September 04, 2019, 06:45:12 am by branadic »
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 
The following users thanked this post: TiN, Andreas, e61_phil, TheSteve, 0.01C, antintedo

Offline branadic

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #610 on: September 05, 2019, 08:36:46 pm »
And just for completeness I received two 3D printed adapters with a ceramic filled resin today, so I changed the front adapter and also installed the rear binding posts. There is no drilling or other modification needed, just simply install the binding posts to the adapter and srew it down to the chassis.

-branadic-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 
The following users thanked this post: TiN, 0.01C

Offline MiDi

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #611 on: September 06, 2019, 10:56:54 am »
A very nice update, it gives even a higher value look.
Could you reveal where to get this posts and their price?
 

Offline branadic

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Re: Advantest R6581 8.5 digit DMM mini teardown/repair
« Reply #612 on: September 06, 2019, 01:23:40 pm »
You can get the binding posts here: http://www.lowthermal.com/cables-and-connectors.php
Please contact them yourself for a quote.

-branadic-
Fluke 8050A | Prema 5000 | Prema 5017 SC | Advantest R6581D | GenRad 1434-G | Datron 4000A | Tek 2465A | VNWA2.x with TCXO upgrade and access to: Keysight 3458A, Keithley 2002, Prema 5017 SC, 34401A, 34410A, Keithley 2182A, HDO6054, Keysight 53230A and other goodies at work
 
The following users thanked this post: 0.01C


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