Author Topic: Prema 5017 / 8017  (Read 11583 times)

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Offline branadic

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Prema 5017 / 8017
« on: October 24, 2017, 04:51:25 am »
I start a new topic on Prema 5017 / 8017. I here posted the question:

What noise would one expect, if DMM measures its own voltage reference in 10V range?

I'm currently observing the reference voltage on my Prema 5017 by itself and I'm the opinion that the noise is rather high. Attached is a picture directly after powering the unit up with capturing data with 0.5Hz repetition rate. I will go one measuring and will then measure the reference voltage with 3458A for comparison. Maybe there is some room for improvement within the circuit by changing some opamps by lower noise types?



For me ~30µVpp is rather high noise in 10V range, when comparing the result with my own LM399.
I found LM399 connected to the non-inverting input of an AD707, which is an improved pin-for-pin replacement for the LT1001, but obsolete by now. I will go on measuring within the cicuit to find where those excessive noise is coming from and how the schematic looks like.

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Online Kleinstein

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Re: Prema 5017 / 8017
« Reply #1 on: October 24, 2017, 05:32:48 am »
The LM399 is way more noisy than a reasonable quality OP. So changing the OP in the reference section has little chance to improve noise. If at all drift might change, if the old one was a poor choice.
The first point would be to find out where the noise is mainly comming from. Usually there are 3 main contributions:
1) input amplifier (including input protection)
2) ADC itself
3) the reference

I would first test the noise with a shorted input. This excludes more of the reference noise. For the 10 V range the input amplifier should not add very much, as the ADC is usually way more noisy than the input amplifier. It is only in the lower ranges that the input amp gets important. Usually the main noise source in the lowest range. The high voltage ranges with a divider might not help very much in the analysis, as they are similar to the lower ones.

Comparing the noise with a short to the noise of a low noise voltage source (e.g. 9 V block) makes the LF reference noise visible.

Normally the noise when measuring the internal reference should be similar to the noise with a short, but it depends - things like filtering could change things for some time scales.
 

Offline The Soulman

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Re: Prema 5017 / 8017
« Reply #2 on: October 24, 2017, 06:03:11 am »
...
The first point would be to find out where the noise is mainly comming from. Usually there are 3 main contributions:
1) input amplifier (including input protection)
2) ADC itself
3) the reference
...

I'd like to add a 4) measurement setup (includes connections, induced noise, etc.)

When measuring the internal reference: how was the connection made and was the housing closed?
« Last Edit: October 24, 2017, 06:20:49 am by The Soulman »
 
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Offline Andreas

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Offline Andreas

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Re: Prema 5017 / 8017
« Reply #4 on: October 24, 2017, 06:18:17 am »
The LM399 is way more noisy than a reasonable quality OP.

But a good (selected) LM399 has around 4uVpp 0.1 - 10 Hz noise.
Further reduction takes place (~1uV) when integration over 2 seconds is done.

with best regards

Andreas
 

Offline branadic

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Re: Prema 5017 / 8017
« Reply #5 on: October 24, 2017, 06:51:30 am »
The LM399 is way more noisy than a reasonable quality OP. So changing the OP in the reference section has little chance to improve noise. If at all drift might change, if the old one was a poor choice.
The first point would be to find out where the noise is mainly comming from. Usually there are 3 main contributions:
1) input amplifier (including input protection)a
2) ADC itself
3) the reference

I would first test the noise with a shorted input. This excludes more of the reference noise. For the 10 V range the input amplifier should not add very much, as the ADC is usually way more noisy than the input amplifier. It is only in the lower ranges that the input amp gets important. Usually the main noise source in the lowest range. The high voltage ranges with a divider might not help very much in the analysis, as they are similar to the lower ones.

Comparing the noise with a short to the noise of a low noise voltage source (e.g. 9 V block) makes the LF reference noise visible.

Normally the noise when measuring the internal reference should be similar to the noise with a short, but it depends - things like filtering could change things for some time scales.

I'm currently performing the short circuit test. Short circuit measurement indicates noise in the same order as measuring the internal reference itself.

Quote

I'd like to add a 4) measurement setup (includes connections, induced noise, etc.)

When measuring the internal reference: how was the connection made and was the housing closed?

No problem, the measurement was done with the case closed and some probe put through some small opening in the chasis.

Question: What noise would one expect, if DMM measures its own voltage reference in 10V range?

I'm currently observing the reference voltage on my Prema 5017 by itself and I'm the opinion that the noise is rather high.

Hello,

if I look at the datasheet of the ADC the noise is explainable for me:

https://www.ohh.de/5610.htm

2 seconds integration time correspond to N1=30 and N2 = 10 thus around 23.6 bits.
Input range is +/-30 V so 60V / 23.6 bits gives 4.7uV.

If I assume that the 3 sigma has to be multiplied (and not divided)
we get around 15uVp / 30uVpp noise alone from the ADC.

So I fear that the analog path with 2uVpp estimated maximum noise is not the mayor source of the noise.

with best regards

Andreas

Seems to be the most reasonable answer by now. However, PRI 5610 was offered in some 28pin DIP package while the Pr BK7 adc inside the Prema 5017 is in a 20pin DIP package, so I expected some difference between both devices also in performance.



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« Last Edit: October 24, 2017, 08:10:32 am by branadic »
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Online Kleinstein

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Re: Prema 5017 / 8017
« Reply #6 on: October 24, 2017, 07:07:06 am »
The LM399 is way more noisy than a reasonable quality OP.
But a good (selected) LM399 has around 4uVpp 0.1 - 10 Hz noise.
...
For a voltage reference the noise of the LM399 is not that bad, but for comparison the 0.1-10 Hz noise for an OP07 is around 0.4 µV. The 1/f noise cross over for the LM399 is also not that different from precision OPs, so looking at different frequency bands would not change that much on the ratio. The LM399 is more noisy than the OP07  at any reasonable frequency. This probably still works for the 741 and LM358.

It takes a really not suitable CMOS OP like the MCP6002 to get something like 6 µV_pp noise.

Also remember that noise from different sources adds like squares. So it would not be a row of 10  OP07 configured as a buffer to give a 4 µV noise, but 100.

OPs noise can be a problem if at a position where the noise is amplified.

One reason for the rather high noise is the 30 V range used to measure 7 V. This range already uses a divider at the input - a divider by 10 and the 3 V if you are lucky, but it could be even divide by 100 and the  300 mV range.
 

Offline zhtoor

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Re: Prema 5017 / 8017
« Reply #7 on: October 24, 2017, 08:23:21 am »
power wires going right over the lm399 reference? is that okay. right next to the toroidal filter core?
 

Offline carl_lab

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Re: Prema 5017 / 8017
« Reply #8 on: October 25, 2017, 01:36:11 am »
power wires going right over the lm399 reference? is that okay. right next to the toroidal filter core?
I think that's the input wires.
 

Offline branadic

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Re: Prema 5017 / 8017
« Reply #9 on: October 25, 2017, 03:39:20 am »
power wires going right over the lm399 reference? is that okay. right next to the toroidal filter core?
I think that's the input wires.

Correct. This is the original wiring, even in my unit.

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Offline branadic

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Re: Prema 5017 / 8017
« Reply #10 on: October 26, 2017, 04:23:20 am »
So Andreas seems to be absolutly right. I performed a "short" measurement on my DVM with integration time of 2s (values 0 - 4.900), 20s (4.900 - 8.300) and 100s (8.300 - till end) in the last days. At 100s integration time the stability of the measurement is mainly dominated by changes in ambient temperature, while noise is as low as ~1.5µVpp (in +/-30V range).

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Offline e61_phil

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Re: Prema 5017 / 8017
« Reply #11 on: October 26, 2017, 05:27:34 am »
It's a pity that this DMM has such ranges (30V). In this case a 10V to 1V transfer can't benefit from the linearity.
 

Offline branadic

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Re: Prema 5017 / 8017
« Reply #12 on: October 26, 2017, 07:57:30 am »
It's a pity that this DMM has such ranges (30V). In this case a 10V to 1V transfer can't benefit from the linearity.

Don't get this statement as the DVM uses 300mV, 3V, 30V, 300V and 1000V ranges, which is quiet useful when measuring a 10V reference with slightly higher output voltage, while a normal 10V range would already go into overload.

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Offline e61_phil

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Re: Prema 5017 / 8017
« Reply #13 on: October 26, 2017, 07:11:45 pm »
The HP ones normaly have an overrange to 120%. So if your 10V reference is more than 20% off, than the range shouldn't be your problem.

Another disadavantage of the 30V range is the input impedance. On all DMMs I know with this 3 instead of 1 FS the high impedance input is only available up to 3V. Therefore, you can't measure 10V directly which such a DMM. You will always have at least an attenuator in the input path. Such a design will not help to reduce noise.


It would be very interesting to do a detailed comparison of the 5017 against a 34401A.

Do you have a computer controllable calibrator to measure the linearity of the 5017 against a 3458A?
« Last Edit: October 26, 2017, 07:16:48 pm by e61_phil »
 

Offline branadic

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Re: Prema 5017 / 8017
« Reply #14 on: October 27, 2017, 02:26:09 am »
Quote
Do you have a computer controllable calibrator to measure the linearity of the 5017 against a 3458A?

No. :(
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Offline The Soulman

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Re: Prema 5017 / 8017
« Reply #15 on: October 27, 2017, 10:30:23 am »
Quote
Do you have a computer controllable calibrator to measure the linearity of the 5017 against a 3458A?

No. :(

If you can do simultaneous data-logging on the 5017 and 3458A you don't need a accurate calibrator, only a bunch of (noise free..)
voltage points, measure those at the same time and plot/compare.
Making a graph of both meters while measuring a slowly discharging capacitor could be all you need.
 

Offline e61_phil

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Re: Prema 5017 / 8017
« Reply #16 on: October 27, 2017, 04:04:41 pm »
A capacitor can't work. I believe for the best result the Prema will need 100s. Therefore, your capacitor should stay sub-ppm stable over 100s. Even if that would be possible, how long should it take from 10V to 0?

Nevertheless, it is of course enough to take any datapoints within in range and measure them with both meters. Measuring simultanously is always a good idea in this case. I also triggeded both instruments simultanously over GPIB. A controllable calibrator is very convienient if you plan to do severeal runs with 100 datapoints.

I also tried to measure linearity with a SR1010. This won't give you 100 datapoints, but no 3458A is needed.
 

Offline branadic

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Re: Prema 5017 / 8017
« Reply #17 on: October 28, 2017, 04:31:51 am »
The maximum I have at hand is a Burster 3401 and a Burster 6401, a 5 decade voltage standard. Nothing for automated measurements though.

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Offline e61_phil

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Re: Prema 5017 / 8017
« Reply #18 on: October 28, 2017, 05:02:31 am »
Is it sub-ppm stable over a few minutes? That should be enough together with a 3458A
 

Offline branadic

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Re: Prema 5017 / 8017
« Reply #19 on: January 03, 2018, 05:51:59 am »
Is it sub-ppm stable over a few minutes? That should be enough together with a 3458A

This question in mind I measured one of the Burster Mikromat DC Standards Typ 3401 we have some 8 hours with our 3458A, both running 24/7 the last weeks, so everything is fully warmed up. Burster DC Standards are based on 1N827.

It seems my LM399 based reference with it's 10V output is even more stable, beside higher noise. Burster 3401 is mains line power, while my reference is powered by a lab power supply. I wonder if this noise can be reduced by using a battery supply? Need to test that.

https://www.eevblog.com/forum/metrology/lm399-based-10-v-reference/msg1389741/#msg1389741

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Offline e61_phil

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Re: Prema 5017 / 8017
« Reply #20 on: January 03, 2018, 08:31:49 am »
Hi,

interesting data! Is it possible to plot the temperature against the output voltage? Or do you simply have some raw data for us?

I like the (old) Burster stuff :)
 

Offline branadic

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Re: Prema 5017 / 8017
« Reply #21 on: January 03, 2018, 09:46:42 am »
Sure, attached are the plot and the raw data set.

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Offline branadic

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Re: Prema 5017 / 8017
« Reply #22 on: February 03, 2018, 06:27:34 am »
I had a call today with Prema respective Mr. Stricker. He remembered that I was once searching for a Prema 5017 / 8017 and wanted to offer me a unit. That said, if you are interested in a Prema device just write to Mr. Stricker and let him know. Most likely you get a mail and the possibility to get what you were searching for with the guarantee of a working unit.

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Re: Prema 5017 / 8017
« Reply #23 on: February 28, 2018, 04:01:50 am »
Hi brandic,

many thanks for extremely useful info -
for years, i have been watching for one Prema 8017, no luck at all, seems almost like one unobtainium.
And now, finally one refurbished, fresh calibrated and adjusted unit is on the way to me - great :-+ ;D :-+
« Last Edit: March 01, 2018, 08:57:56 am by bozidarms »
 

Offline branadic

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Re: Prema 5017 / 8017
« Reply #24 on: September 17, 2018, 07:05:31 am »
There is currently a Prema 8017 available on the bay. Even though stated as defect there seems to be only an issue while booting. Nothing that sounds unfixable.

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Offline branadic

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Re: Prema 5017 / 8017
« Reply #25 on: October 02, 2018, 04:24:43 am »
Again I have to vote for Prema meters and their service.  :-+
Had my unit out for service and calibration in Mainz. The unit was sold to Bosch in 2001. After 17 years without calibration the values on DCV only in 300mV range where slightly out of spec. ACV fully in spec, ACV+DCV  fully in spec, DCI fully in spec, ACI fully in spec, ACI+DCI fully in spec, 2W and 4W ohms where selective out of spec.
Only 6 electrolytic capacitors where replaced. Saftey inspection passed wihtout any issues. Scanner is fully working. So this gear is reliable as hell and received without any additional errors today. The price was below half of what Keysight asks for calibration of a 3458A, so maybe you pay them for the extra errors they integrate to your gear?  :-DD

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Offline e61_phil

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Re: Prema 5017 / 8017
« Reply #26 on: October 02, 2018, 04:30:05 am »
The accuracy is also below half of what the 3458A will do.
 
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Offline branadic

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Re: Prema 5017 / 8017
« Reply #27 on: October 02, 2018, 04:36:40 am »
Sure, but Prema understood service from a customers point of view as LT did, while Keysight is more like a vampire, hungry for your money.

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Re: Prema 5017 / 8017
« Reply #28 on: October 02, 2018, 05:13:26 am »
If you think Keysight is hungry, try Fluke Calibration  :-DD
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Offline branadic

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Re: Prema 5017 / 8017
« Reply #29 on: October 02, 2018, 05:45:29 am »
Well, calibrating a Keithley2002 at Tektronix/Fluke/Keithley is 480€ for the calibration + 105€ for the report + 50€ for transport.  :wtf:
Keysight asks for 712€ without telling you what you pay in detail for, a vampire policy.  |O
The price list of Prema is public and says 55€ for the as found report + 262€ for the adjustment and calibration including report.

Since calibration is a fully automated process, everything else would be silly, Keithley and Keysight ask to much money, that's for sure. But the business model works since this crazy quality management system forces you to blow out this money and there are only a few competitors out there with sometimes unknown or suspect quality.

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Offline e61_phil

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Re: Prema 5017 / 8017
« Reply #30 on: October 02, 2018, 06:06:38 am »
712€ is much and ~1500€ for the 8508A is much more and perhaps it is much more than it is worth, BUT you can't compare a 3458A or 8508A with the lower accuracy meters. There is no calibrator which can directly calibrate a 3458A or 8508A with a good TUR. There is some more work to do to lower the uncertainties. In contrast to that a 20ppm meter is really as easy as you described it.

The quality management don't force you to bring the 3458A to keysight. You have to have a unbroken chain to your NMI, but another cal lab is also ok. We pay much less than 712€ for our 3458As.
« Last Edit: October 02, 2018, 06:09:39 am by e61_phil »
 
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Offline branadic

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Re: Prema 5017 / 8017
« Reply #31 on: October 02, 2018, 06:39:08 am »
That said, you will always find someone who is more barefaced, no worries whatsoever. It's pretty simple, put a label like "baby", "marry" or "metrology" on it and you can ask any price you want. As long as noone complains, nothing will change.

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Re: Prema 5017 / 8017
« Reply #32 on: October 02, 2018, 07:41:49 am »
The quality management don't force you to bring the 3458A to keysight.

e61_phil So true :)
One can calibrate 3458A even to 9V battery and 10K resistor 0.1% from Digikey, and it will be calibrated indeed. Question is, to what?  :=\

Without exact datapoints (we didn't see any of it for above-mentioned 8017 nor 3458) talking about calibration prices is just waste of bits and bytes. Even 100$ for 10V 20ppm calibration might be too much, while 2000$ for 10V 2ppm calibration - justified if needed. And automated calibration does not mean it's free. Maintaining calibrator/standards to their best spec is lot of time, money and effort, automated or not. :)
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Offline branadic

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Re: Prema 5017 / 8017
« Reply #33 on: October 02, 2018, 08:00:08 am »
Quote
Without exact datapoints (we didn't see any of it for above-mentioned 8017 nor 3458) talking about calibration prices is just waste of bits and bytes.

So is your comment on that.

Quote
And automated calibration does not mean it's free. Maintaining calibrator/standards to their best spec is lot of time, money and effort, automated or not. :)

Noone asked for something free, but the bucks they ask for is definitely to much. And the price for printing what they have measured is simply barefacedness. You can have your opinion, I have mine. Thank you very much.

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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 branadic

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Re: Prema 5017 / 8017
« Reply #34 on: October 07, 2018, 06:42:43 am »
There are currently two Prema 5017 units sold as defect / spare parts on ebay. At least on of them has the scanner build in. Maybe someone wants to start a repair thread?

-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
 

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Re: Prema 5017 / 8017
« Reply #35 on: October 23, 2018, 08:22:27 am »
I couldn't resist and since noone of this board took the chance I bought both units. They arrived today and both of them came with the scanner  :-+

One is hanging, which simply indicates a communication issue between the MCU board and the analog board, maybe due to some bad power rail. Need to check that, which shouldn't be of an issue, since I received the schematics from Prema Semiconductor and since almost all parts are standard components available today.

The second one didn't power up. The issue was pretty simple to find. The POWER ENTRY MODULE EMI FILTERS (Delta Electronics 06AK5) had a broken 110V/220V switch. So I simply used the one from the first unit and bingo, it's working. Ordered two of them today and will replace them in both unit.

By the way, I got some insider information why they stopped selling and developing meters. The 5017 and 8017 have been the first meters using SMD components. They only sold about 400 unit per year. In the very beginning of the year 2k it was hard to almost impossible to get even standard passive SMD components. Prices for precision opamps doubled. TI controller discontinued even though they where told the that they will be in production for a very long time like the 8086. So most of the developer had nothing to do. This was the time when the management decided to stop developement and production. After SMD crisis, when management wanted to continue, all developers had left the comany, so there was noone left except some technicans. Pretty sad.

-branadic-
« Last Edit: October 23, 2018, 08:39:27 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
 
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Re: Prema 5017 / 8017
« Reply #36 on: October 23, 2018, 03:53:27 pm »
Thanks for the story. Now it's the opposite situation, that you can't find thru-hole packaged parts. For example direct replacement for LF356BN ain't easily available, you either have to go expensive hermetic TO-packages or bodge adapters for SOIC8 or SSOP parts.  :rant: Sure there are other parts in DIP that can be subbed, but I like to keep repairs as 1:1 when possible , unless I'm convinced in improvement.
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Re: Prema 5017 / 8017
« Reply #37 on: November 10, 2018, 06:21:23 am »
There is currently a Prema 5017 SC for offer:

https://www.eevblog.com/forum/buysellwanted/fs-prema-5017sc-7-5-digit-dmm-(location-germany)/msg1900313/#msg1900313

I recently sold one of my units, fresh serviced (hardware and software updates) and calibrated.

-branadic-
« Last Edit: November 14, 2018, 04:56:23 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
 

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Re: Prema 5017 / 8017
« Reply #38 on: November 11, 2018, 02:28:00 am »
Also have a fully working Prema 5017 that I wouldn't mind selling, if the price is right.
I want $800 or 800Swiss Francs. Local pickup or shipped to Switzerland/Germany.

 

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Re: Prema 5017 / 8017
« Reply #39 on: March 01, 2019, 03:32:28 pm »
branadic, did you had the chance to compare the noise level on your different units ? also I'm wondering if servicing improved the noise problem.

Recently got a Prema 5017 and compared to my 34401a it's really noisy. Pretty sure something is wrong inside. probably some caps.
 

Offline maginnovision

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Re: Prema 5017 / 8017
« Reply #40 on: March 01, 2019, 07:20:00 pm »
branadic, did you had the chance to compare the noise level on your different units ? also I'm wondering if servicing improved the noise problem.

Recently got a Prema 5017 and compared to my 34401a it's really noisy. Pretty sure something is wrong inside. probably some caps.

I bought his recently serviced Prema 5017. I calibrated a couple of power supplies but I've had it connected to my DMMCheck Plus(aged about 6000 hours now) and it's been sitting between 4.9999365 and 4.9999512 for a couple hours. Seems ok considering the conditions here. When the AC isn't going off and on it doesn't usually move more than 1 uV a step when it does(10s time).
 
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Re: Prema 5017 / 8017
« Reply #41 on: March 01, 2019, 11:13:13 pm »
I bought his recently serviced Prema 5017. I calibrated a couple of power supplies but I've had it connected to my DMMCheck Plus(aged about 6000 hours now) and it's been sitting between 4.9999365 and 4.9999512 for a couple hours. Seems ok considering the conditions here. When the AC isn't going off and on it doesn't usually move more than 1 uV a step when it does(10s time).

Interesting. It confirm my suspicion. 2s integration time ? filter on or off ?

Thanks a lot for the info.
 

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Re: Prema 5017 / 8017
« Reply #42 on: March 02, 2019, 04:17:06 am »
I bought his recently serviced Prema 5017. I calibrated a couple of power supplies but I've had it connected to my DMMCheck Plus(aged about 6000 hours now) and it's been sitting between 4.9999365 and 4.9999512 for a couple hours. Seems ok considering the conditions here. When the AC isn't going off and on it doesn't usually move more than 1 uV a step when it does(10s time).

Interesting. It confirm my suspicion. 2s integration time ? filter on or off ?

Thanks a lot for the info.

2s, filter on it changes by 1uV when it changes.. Can't be sure if it's the meter or ref though. dmmcheck plus isn't the best especially looking at uV. I think it's a couple uV p-p noise.

EDIT: My rs232 card died(found out when I tried to hook up meter) when the ne one comes I can graph it.
« Last Edit: March 02, 2019, 04:29:32 am by maginnovision »
 
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Re: Prema 5017 / 8017
« Reply #43 on: March 03, 2019, 07:19:49 am »
So I spent some time yesterday doing a setup to compare my 34401a to the 5017.

The setup:
- 10V LT1021 based voltage source.
- 34401a in High impedance mode, NPLC 10, 10V range.
- 5017, 2s Integration, Filter ON.
- Boths meter connected to the same source.
- 2 hours warmup time (source is always hot).
- Sampling every 3 sec for 7 hours.

This is the deviation in ppm of each meters


Considering the integration time of the 5017 vs the 34401a (2s vs 166.66ms), I was expecting the 5017 to be a lot more stable. So my 5017 is definitly sick.



« Last Edit: March 03, 2019, 10:43:51 am by Kosmic »
 

Online Kleinstein

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Re: Prema 5017 / 8017
« Reply #44 on: March 03, 2019, 07:35:39 am »
The curve really looks like a sick meter.

There are a few more test that could be done: like check the noise with a short at the input in a few ranges. This would eliminate the meters reference from the test.
One could also directly check the noise of the 5017 internal reference.

A possible other cause of trouble could be a relay contact at the input. When not used for a long time contacts can have contact problems.
 
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Offline branadic

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Re: Prema 5017 / 8017
« Reply #45 on: March 03, 2019, 07:49:15 am »
branadic, did you had the chance to compare the noise level on your different units ? also I'm wondering if servicing improved the noise problem.

Recently got a Prema 5017 and compared to my 34401a it's really noisy. Pretty sure something is wrong inside. probably some caps.

Did some minor comparisons but nothing I really documented to show here. Your noise looks really high and I would suggest checking the hardware. If you sent me an email I can send you the schematics including the upgrades they made. You can also contact Prema for the software update that all my units got when they were for service and calibration.

-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
 
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Offline maginnovision

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Re: Prema 5017 / 8017
« Reply #46 on: March 03, 2019, 06:23:00 pm »
I'm going to log overnight. After about an hour I was getting peaks of 2ppm/-1.6ppm and average of -9.34E-10ppm, so most likely longer sample time would make that better. Running 2S, filter on. Not logging temp but it's still getting colder. Should stabilize soonish.
« Last Edit: March 03, 2019, 08:15:20 pm by maginnovision »
 
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Re: Prema 5017 / 8017
« Reply #47 on: March 04, 2019, 02:34:06 am »
If you sent me an email I can send you the schematics including the upgrades they made.

PM sent
 

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Re: Prema 5017 / 8017
« Reply #48 on: March 04, 2019, 02:35:44 am »
I will probably stop the tests right away on my unit and put it in the repair queue for a complete disassembly  :)

Thanks a lot for your feedback guys.
« Last Edit: March 04, 2019, 08:18:19 am by Kosmic »
 

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Re: Prema 5017 / 8017
« Reply #49 on: March 04, 2019, 08:04:32 am »
I know you're gonna get it fixed but here is what I got. 12 hours from 11:00pm - 11:00am, and one graph when I was actually asleep from 2:00am - 8:00am. The heater would have been running off/on during the night as well. Still 2 seconds integration with filter on. I threw a sweater over the DMMCheck Plus while I slept to try to insulate it from the heater but the DMM was fully exposed.
 
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Re: Prema 5017 / 8017
« Reply #50 on: March 04, 2019, 08:14:16 am »
Hello,

would be interesting to have a Allan Deviation Diagram on the sleeping part.

with best regards

Andreas
 

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Re: Prema 5017 / 8017
« Reply #51 on: March 04, 2019, 12:07:25 pm »
Here is one from alavar. Thought I'd add that was WITH math ax+b to get 100nV digit adding extra noise. Going to do another log without it tonight and compare.
« Last Edit: March 04, 2019, 12:33:54 pm by maginnovision »
 
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Re: Prema 5017 / 8017
« Reply #52 on: March 05, 2019, 05:49:53 am »
I know you're gonna get it fixed but here is what I got. 12 hours from 11:00pm - 11:00am, and one graph when I was actually asleep from 2:00am - 8:00am. The heater would have been running off/on during the night as well. Still 2 seconds integration with filter on. I threw a sweater over the DMMCheck Plus while I slept to try to insulate it from the heater but the DMM was fully exposed.


Really usefull data for me. Give me a target to declare my meter fixed  :)

Thanks a lot!
 

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Re: Prema 5017 / 8017
« Reply #53 on: June 05, 2019, 07:14:38 am »
So I finally opened up my 5017 to test some caps and do a visual inspection. I ended up changing all the electrolytic on the analog board (tested bad) and some in the power supply.



I didn't really check the dimension of the replacement capacitors I ordered, so I had to install 2 of them on the side.



Did another comparison with my 34401a and the 10V LT1021 source. Integration time was 200ms (averaging disabled) on the 5017 and NPLC 10 on the 34401a.



Standard deviation
5017:  0.0000447757571
34401a: .0000172379238

Look like changing the bad caps helped a lot. I need to check the other measurement mode though. I think there still a problem with 4Wires resistance mode.
« Last Edit: June 05, 2019, 12:02:58 pm by Kosmic »
 

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Re: Prema 5017 / 8017
« Reply #54 on: June 05, 2019, 07:26:53 am »
Very good, when I had problems not long ago with some severe "noise" it turned out to be one of the power supply caps as well. One of them was very very hot the other was only warm. I replaced both of the big ones near the edge and it came back to normal.
 

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Re: Prema 5017 / 8017
« Reply #55 on: June 06, 2019, 04:37:56 am »
Is this a known issue also with 8017? I’m just about to send my 8017 to Prema for calibration and input socket replacement. I wonder if they replace these/bad caps by default?
« Last Edit: June 06, 2019, 04:39:38 am by exor »
 

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Re: Prema 5017 / 8017
« Reply #56 on: June 06, 2019, 05:05:25 am »
I'm not sure if it's a known issue but I'd say that supply rails are important on any device and if the caps are sat next to the regulators they're eventually going to fail in a way you notice. I'm not sure if they do replacement by default, branadic might know better. I believe he said they replaced them on both of the 5017's he sent in but he may have asked for that.

If they update the software perhaps you could upload a drive image?
« Last Edit: June 06, 2019, 05:23:58 am by maginnovision »
 

Offline chronos42

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Re: Prema 5017 / 8017
« Reply #57 on: June 06, 2019, 05:47:02 am »
I'm not sure if it's a known issue but I'd say that supply rails are important on any device and if the caps are sat next to the regulators they're eventually going to fail in a way you notice.
If they update the software perhaps you could upload a drive image?

The caps are a well known issue of these devices, all caps should be replaced.
The latest 5017 firmware is rev. 12, I have attached it.

For a firmware update of a 8017 I recommend to ask Prema for the updatesoftware.
« Last Edit: June 06, 2019, 07:25:17 am by chronos42 »
 
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Re: Prema 5017 / 8017
« Reply #58 on: June 06, 2019, 06:10:44 am »
Thanks to both for the information, I will ask them about caps. The FW update I already wrote to Service Request form.
 

Offline jaromir

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Re: Prema 5017 / 8017
« Reply #59 on: June 06, 2019, 07:46:03 am »

Did another comparison with my 34401a and the 10V LT1021 source. Integration time was 200ms (averaging disabled) on the 5017 and NPLC 10 on the 34401a.


Please correct me if I am reading the graph wrong, but does both 34401 and 5017 read roughly 50-100uV peak-to-peak of noise from LT1021?
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Online Kosmic

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Re: Prema 5017 / 8017
« Reply #60 on: June 06, 2019, 11:23:46 am »
Please correct me if I am reading the graph wrong, but does both 34401 and 5017 read roughly 50-100uV peak-to-peak of noise from LT1021?

Yes around 100uV p-p. The source is powered by a bench power supply (linear).
 

Online Kosmic

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Re: Prema 5017 / 8017
« Reply #61 on: June 06, 2019, 11:26:20 am »
I'm not sure if it's a known issue but I'd say that supply rails are important on any device and if the caps are sat next to the regulators they're eventually going to fail in a way you notice.
If they update the software perhaps you could upload a drive image?

The caps are a well known issue of these devices, all caps should be replaced.
The latest 5017 firmware is rev. 12, I have attached it.

For a firmware update of a 8017 I recommend to ask Prema for the updatesoftware.

Yeah, kind of disappointing that they were installing cheap capacitors  :-\ I left some of them in place since they tested ok but I should have replaced them all.

Thanks a lot for the firmware! will update mine.
« Last Edit: June 06, 2019, 11:28:28 am by Kosmic »
 

Offline e61_phil

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Re: Prema 5017 / 8017
« Reply #62 on: June 06, 2019, 07:11:14 pm »
Please correct me if I am reading the graph wrong, but does both 34401 and 5017 read roughly 50-100uV peak-to-peak of noise from LT1021?

Yes around 100uV p-p. The source is powered by a bench power supply (linear).

100uVpp is way to high for a 34401A. Could it be the reference source?
 

Online Kosmic

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Re: Prema 5017 / 8017
« Reply #63 on: June 07, 2019, 12:08:08 am »
Please correct me if I am reading the graph wrong, but does both 34401 and 5017 read roughly 50-100uV peak-to-peak of noise from LT1021?

Yes around 100uV p-p. The source is powered by a bench power supply (linear).

100uVpp is way to high for a 34401A. Could it be the reference source?

Yes, I don't think it's coming from the 34401a. I checked the power supply and it seam to be ok. The regulator in the voltage reference seem to do a poor job at filtering noise.

Anyway, my goal was to try to fix the 5017. So, in the end it seem noisier then the 34401a but nevertheless accurate over time.

 

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Re: Prema 5017 / 8017
« Reply #64 on: June 07, 2019, 01:58:38 am »
Please correct me if I am reading the graph wrong, but does both 34401 and 5017 read roughly 50-100uV peak-to-peak of noise from LT1021?

Yes around 100uV p-p. The source is powered by a bench power supply (linear).

100uVpp is way to high for a 34401A. Could it be the reference source?

My results weren't much different powering an LT1021 with a rigol dp832. About 10ppm p-p over 12 hours, 5ppm p-p while it was mostly left alone. Mine was a DMMCheckPlus completely unshielded using pretty crappy leads and alligator clips.
 

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Re: Prema 5017 / 8017
« Reply #65 on: June 07, 2019, 02:13:13 am »
I attached a measurement of my 34401As connected to my Fluke 5440B at 10V. The temperature varies a lot on a hot summer day. But even with that kind of temperature variations it is far from 100µVpp (10ppm)
 

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Re: Prema 5017 / 8017
« Reply #66 on: June 07, 2019, 02:22:46 am »
My ltz1000A and non-A are also way lower with temp variations but those aren't LT1021's.
 

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Re: Prema 5017 / 8017
« Reply #67 on: June 15, 2019, 12:12:17 am »
Captured some data over night again, but this time with 10s integration (averaging off). And as expected, noise was reduced at around 50uV p-p (over multiple hours). I double checked the power supply and it seem to be in spec in term of ripple and noise (1mV p-p).



I'm also done testing the PM5017 and it seem to be working perfectly in all mode. So changing the caps was the only thing he needed.
« Last Edit: June 15, 2019, 12:20:35 am by Kosmic »
 


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