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Offline e61_philTopic starter

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Fluke 5440B Problems
« on: July 11, 2016, 08:55:31 am »
Hi,

I bought a Fluke 5440B. Unfortunately, the unit has two issues. The first one is a fault message on power up "INSIDE GUARD FAULT  CHECK GUARD CONTROL BUS". I think that isn't a big deal. And everything seems to work after pressing any key.

The real problem is a instability of the output voltage, if the voltage is above aprox. 500V. The reading on my HP 3456A jumps up a few tens of mV (10NPLC) at 1000V every few seconds and returns.

I attached two scope measurements (only different time scales). The measurement was taken with a 10nF capacitor in series to 1:10 Probe.

My guess is, there is a high voltage breakdown anywhere (component or PCB) and the output stage of the 5440B isn't fast enough to regulate the voltage.

I've measured the driving waveform which drives the high voltage transformer and the peak-peak values matches the values given by the service manual. But the rise time of the square wave isn't as steep as described in the manual (1µs). The waveform looks stable on the scope.

I also measured the voltage on the high voltage capacitor on the output PCA and on the Filter B PCA. The voltage is about 30V higher than the output (the manual says 27V, but I think that is ok). And one can measure these instabilities already on these caps.

I wrote this, because I sold my Fluke 343A to buy the Fluke 5440B (cause of the WAF ;) ). Therefore, I have only a few days left with my Fluke 343A which could deliver stable high voltages instead of the high voltage transformer.

Or does anyone has a guess which part could be damaged?

Thanks
Philipp
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Offline zlymex

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Re: Fluke 5440B Problems
« Reply #1 on: July 11, 2016, 09:44:40 am »
Try cleaning all the relays first, that is the suggestion from someone who has successfully repaired many 5440Bs.
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Offline e61_philTopic starter

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Re: Fluke 5440B Problems
« Reply #2 on: July 11, 2016, 11:11:50 am »
That sounds relaxing :)

Do you know a preferable cleaning procedure?
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Offline Dr. Frank

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Re: Fluke 5440B Problems
« Reply #3 on: July 11, 2016, 12:03:57 pm »
@Philipp:
Sorry, I was not able in the weekend, to make your requested comparison measurements.
Maybe I find a bit of time during the week.

@zlymex:
I also wonder, how to clean these relays contacts, without scratching or destroying this sensitive Au plating.

I also thought about cleaning, as my 5442A shows a difference between plus and minus polarity regarding offset, gain and linearity behaviour. Everything is inside specification, but if the negative range would behave exactly like the positive, which I would suspect due to the relays switching scheme, then my instrument would be much more consistent and precise.

Thanks - Frank
 
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Offline e61_philTopic starter

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Re: Fluke 5440B Problems
« Reply #4 on: July 11, 2016, 12:11:50 pm »
@Dr. Frank: I already thought you have no time to do this measurement. In cause of your fast reactions to my questions everytime :) Thanks a lot for your time!
I think I should try to clean the relays before you spend your time in measuring anything for me.
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Offline RobK_NL

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Re: Fluke 5440B Problems
« Reply #5 on: July 11, 2016, 01:57:22 pm »
@Philipp:
The power-on fault message may be due to  malfunctioning of the inguard Power-on-Reset circuit (#GPOP). I had a similar problem and tracked it down (eventually) to a dead cap; C31 on the A10 board.
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Offline e61_philTopic starter

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Re: Fluke 5440B Problems
« Reply #6 on: July 11, 2016, 09:17:29 pm »
Quote from: RobK_NL on July 11, 2016, 01:57:22 pm
@Philipp:
The power-on fault message may be due to  malfunctioning of the inguard Power-on-Reset circuit (#GPOP). I had a similar problem and tracked it down (eventually) to a dead cap; C31 on the A10 board.

Someone has already replaced C31 with a new 100µF Cap... But that is a good starting point :) Thanks
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Offline zlymex

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Re: Fluke 5440B Problems
« Reply #7 on: July 12, 2016, 12:25:19 am »
I cleaned all the relays of my 5440B once, it showed some guarding related error messages before the cleaning.
I used paper card soaked with pure alcohol to rub all the contact.
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Offline ManateeMafia

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Re: Fluke 5440B Problems
« Reply #8 on: July 12, 2016, 01:30:37 am »
I used the same method as zlymex on a Fluke 5450A. I also followed the cleaning with some Deoxit Gold on card stock. It did a great job cleaning the contacts.
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Offline e61_philTopic starter

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Re: Fluke 5440B Problems
« Reply #9 on: July 12, 2016, 08:59:35 pm »
This evening I started cleaning the relays on the output PCA. I started with the big relays (they were much easier to open). As I finshed cleaning the big relays I want to go to bed, but first I have to give it a try ;)

Therefore, I selected 1000V on the Fluke 5440B and had a look on my HP 3456A. The reading was very stable (except the warm up drift, but that is only drift no jump). I left it running for about 10 to 15 minutes and then the jumping output was back. It seems to be a thermal issue. What do you think? I wouldn't expect such a behavior from a dirty relay contact? Or should I?
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Offline acbern

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Re: Fluke 5440B Problems
« Reply #10 on: July 12, 2016, 09:05:52 pm »
better check caps.
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Offline e61_philTopic starter

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Re: Fluke 5440B Problems
« Reply #11 on: July 13, 2016, 04:51:35 am »
@acbern: which caps do you mean? The high voltage ones or electrolytics?

Below approx. 500V these jumps vanishes. Therefore, I would expect something in the high voltage path.
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Offline RobK_NL

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Re: Fluke 5440B Problems
« Reply #12 on: July 13, 2016, 01:25:12 pm »
The high voltage is generated by a converter on the "Filter B" PCA. The supply voltage for it is changed based on the output voltage range. I would check C21 and C22 and also the opto triacs that do the switching.
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Offline BU508A

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Re: Fluke 5440B Problems
« Reply #13 on: July 18, 2016, 07:32:54 pm »
Hi,

Quote from: e61_phil on July 13, 2016, 04:51:35 am
@acbern: which caps do you mean? The high voltage ones or electrolytics?

Below approx. 500V these jumps vanishes. Therefore, I would expect something in the high voltage path.

Yes, probably. But it is always a good idea to replace in such old gear all the tantalum caps.
Did it so in my Fluke 3330B and jumping of the output calms down significantly.
Tantalums have a tendency to "sparkle", especially the old ones.

Andreas
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Offline e61_philTopic starter

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Re: Fluke 5440B Problems
« Reply #14 on: July 18, 2016, 09:59:34 pm »
Quote from: BU508A on July 18, 2016, 07:32:54 pm

Yes, probably. But it is always a good idea to replace in such old gear all the tantalum caps.
Did it so in my Fluke 3330B and jumping of the output calms down significantly.
Tantalums have a tendency to "sparkle", especially the old ones.

Andreas

Thanks. I already started replacing most of the electrolytics. I will go on with the tantalum ones. Did you replace these caps with anything special?
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Offline BU508A

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Re: Fluke 5440B Problems
« Reply #15 on: July 19, 2016, 06:13:52 am »
Quote from: e61_phil on July 18, 2016, 09:59:34 pm
Thanks. I already started replacing most of the electrolytics. I will go on with the tantalum ones. Did you replace these caps with anything special?

Yes. First, I look into the schematic if it is available. Most of these Tantalums are used as blocking capacitors. These I'll replace
with Wima MKP caps (Polypropylen dielectricum) if the capacity and mechanical dimensions fits.
If the Wima doesn't fit, I'm looking for low ESR, low leakage  types, e.g. from Panasonic.

I'm trying to avoid Tantalum caps for some reasons:
- I do not trust them at all, even the new ones (Yes, I know they have improved. But ...)
- Tantalum is political problematic
- piezoelectric effect

I suspect, that in the 70's and 80's a lot of Tantalums were used because it was new, fancy and they have usually a real low ESR.

Btw, here is a nice overview from Wima, comparing some different caps:

English version:
  http://www.wima.de/EN/characteristics.htm
  more information: http://www.wima.de/EN/technicalinformation.htm

German version (interestingly, they show a bit different information, compared to the english one):
  http://www.wima.de/DE/technicalinformation.htm
  http://www.wima.de/DE/characteristics.htm

Panasonic caps (Yes, I know, these are SMDs, but soldering some silver coated copper wire will do the job  ;) ):
  http://www.mouser.de/ds/2/315/ABE0000C65-911134.pdf
  http://www.mouser.de/panasonic-polymer-caps/

Andreas

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Offline ap

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Re: Fluke 5440B Problems
« Reply #16 on: July 19, 2016, 08:24:55 pm »
Instead of Wima PP (which may not fit) I would recommend Oscons. They are especially good at filterung and do not have the ripple current restrictions that should have led to the conclusion  back then to not use them. How do I know? We built industrial computer boards at that time, and when we looked at that, we found there was no way to use Tantalums as 5V blocking specs, so we had to change them. We learnt it the hard way, unfortunatelly...
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Offline Echo88

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Re: Fluke 5440B Problems
« Reply #17 on: December 30, 2017, 11:57:14 pm »
I also recently got my Fluke 5440B/AF which had an error. Maybe someone has the same problem and my solution might help.
 
Calibrator starts okay, but after a few seconds doenst respond anymore to the Frontpanel, all Frontpanel-LEDs flickering, Display shows "Fluke DV Calibrator", Fault-LED lights. Sometimes it also did show Front-Communic-Error or Memory-Error.

The solution: The 5V-supply-voltage (Test point 2, not 5V-HR) on the Outguard-control-Supply was jumping between 4.8 - 3.9V, which led to the Frontpanel-Errors and the flickering LEDs. In my case the pcb under R1 (current shunt) was slightly dark due to the heating of R1. I checked the value of R1 and found it to be about 350mR while it should be 150mR according to the service schematic. After changing the resistor the 5V-supply-voltage was nice and smooth again with the correct value.
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Offline Bill158

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Re: Fluke 5440B Problems
« Reply #18 on: January 01, 2018, 05:00:49 pm »
Quote from: Echo88 on December 30, 2017, 11:57:14 pm
The solution: The 5V-supply-voltage (Test point 2, not 5V-HR) on the Outguard-control-Supply was jumping between 4.8 - 3.9V, which led to the Frontpanel-Errors and the flickering LEDs. In my case the pcb under R1 (current shunt) was slightly dark due to the heating of R1. I checked the value of R1 and found it to be about 350mR while it should be 150mR according to the service schematic. After changing the resistor the 5V-supply-voltage was nice and smooth again with the correct value.
How interesting.  I had the same failure of R1 in my 5440B when I first received it.  But what made things a little more interesting was that the resistance would go radically up as the temperature of R1 went up.  So when I first turned on the unit everything was ok and then things would start going bad slowly.  I also saw that the 5V was dropping slowly until it was below what was needed to make everything work correctly.  I replaced R1 but increased it to a 5W just in case.  FLUKE must have gotten a batch of bad resistors but of course they were OK in the beginning and only became defective over the years.
Bill
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Offline Echo88

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Re: Fluke 5440B Problems
« Reply #19 on: January 02, 2018, 01:01:18 am »
Just tried to do the Intern Calibration Routine, but it gets stuck in the +10V Zero Calibration and just clicks relays. Seems i also need to clean the relays? Hopefully its nothing serious. Analog and Digital Self Test states no errors. I also wanted to build a RS232-cable to get the capability of reading out the calibration values/analog self test results. Anyway, gotta read the handbooks.  :popcorn:

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Offline Echo88

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Re: Fluke 5440B Problems
« Reply #20 on: January 02, 2018, 08:13:51 pm »
Couldnt get the RS232-cable to work properly today (need to get my hand around the DTR-stuff the calibrator requires). But then again i tested the calibrator after 2h warm-up time with the Internal Calibration Routine and it did work today without problems. After a ACAL of my 3458A i was absolutely flabbergasted: It shows spot on 10.000000V when the Calibrator puts 10V out.  :scared: :-+

And all that after the trip from the USA to here and i see no sticker on it / cant conclude when it was last calibrated. I love this thing.  ;D

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Offline e61_philTopic starter

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Re: Fluke 5440B Problems
« Reply #21 on: January 02, 2018, 09:27:35 pm »
Quote from: Echo88 on January 02, 2018, 08:13:51 pm
Couldnt get the RS232-cable to work properly today (need to get my hand around the DTR-stuff the calibrator requires). But then again i tested the calibrator after 2h warm-up time with the Internal Calibration Routine and it did work today without problems. After a ACAL of my 3458A i was absolutely flabbergasted: It shows spot on 10.000000V when the Calibrator puts 10V out.  :scared: :-+

And all that after the trip from the USA to here and i see no sticker on it / cant conclude when it was last calibrated. I love this thing.  ;D

Great! :)

The RS-232 doesn't need anything special. I built one in december and I only connected TX and GND to the PC.
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Offline Dr. Frank

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Re: Fluke 5440B Problems
« Reply #22 on: January 02, 2018, 09:41:04 pm »
Quote from: Echo88 on January 02, 2018, 08:13:51 pm
.. But then again i tested the calibrator after 2h warm-up time with the Internal Calibration Routine and it did work today without problems. After a ACAL of my 3458A i was absolutely flabbergasted: It shows spot on 10.000000V when the Calibrator puts 10V out.  :scared: :-+

And all that after the trip from the USA to here and i see no sticker on it / cant conclude when it was last calibrated. I love this thing.  ;D

Congrats!

What about the other ranges, 22V, 275V and 1100V, to which degree  do they linearily agree with the 11V range, when measured with your 3458A?
(Test 300V on the 1100V range..)

Frank
« Last Edit: January 02, 2018, 09:43:05 pm by Dr. Frank »
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Offline Echo88

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Re: Fluke 5440B Problems
« Reply #23 on: January 02, 2018, 11:03:29 pm »
@Dr. Frank: Its a little late today, i will let both instruments run over night and make those measurements tomorrow. Can you specify the needed datapoints? Otherwise i will just measure
+-10V,15V,22V,100V,220V,300V,400V,500V,600V,700V,800V,900V,1000V. How much time is needed for the 3458A to thermally stabilize at the high voltages? I know the 3458A will be a few ppm off at the high voltages.
@e61_phil: Thanks, the RS232-cable works well now that ive disconnected the DTR/DTS-wires. Thought they were necessary.

Just did a Analog Selftest and Internal Calibration Routine. I have absolutely no idea if that plotted data might help someone fix their 5440B or show them which values are plausible, but here it is:


JOHN FLUKE MFG. CO., INC.                          5440  ANALOG DIAGNOSTICS

---------------------------------------------------------------------------

     ADM1: +.000000V
     ADM2: -.002547V
     ADM3: +2.53159V
     M1: +13.0654V
     M1: +13.0654V
     M3: -11.6912V
     M4: -16.7795V
     C1: +5.08826V
     M5: -5.05291V
     M6: -16.5145V
     M7: -9.67262V
     C2: -13.0935V
     M8: -13.0935V
     C3: ¼.000000V
     M9: -4.96851V
     M10: -1.51081V
     C4: -3.23966V
     M11: -3.24050V
     C3: +.000844V
     M12: -15.5156V
     M13: -16.7690V
     C5: +1.25335V
     M14: -10.0664V
     M15: +9.97923V
     M16: -.045014V
     M17: +.000000V
     M18: -.001394V
     C6: +.001394V
     M19: -.000236V
     M20: -.001776V
     C7: +.001539V
     M21: -.000285V
     M22: -.000348V
     M23: +.000058V
     M24: +.000066V
     M25: +.005150V
     M26: +10.0026V
     M27: +20.0420V
     M28: -10.0026V
     M29: +.000000V
     M30: +19.9995V
     M31: -.093966V
     M32: +19.9995V
     M33: -.000371V
     M34: +20.0350V
     M35: +20.0280V
     M36: +17.8040V
     M37: -.157540V
     M38: +.188073V
     M39: +.839009V
     M40: +.857412V
     C8: -.018403V

END OF ANALOG DIAGNOSTICS

JOHN FLUKE MFG. CO., INC.                        5440  INTERNAL CALIBRATION

---------------------------------------------------------------------------

+10V ZERO
     1: N1=  8, N2=13514, Offset    +.3uV

RESOLUTION RATIO
     1: N1=  7, N2=20763, Offset    +.4uV

-10V ZERO
     1: N1=  8, N2=10489, Offset    -.1uV

+20V ZERO
     1: N1=  8, N2=13189, Offset   +1.2uV

-20V ZERO
     1: N1=  8, N2=10805, Offset    +.6uV

+250V ZERO
     1: N1=  8, N2=12818, Offset   +1.0uV

-250V ZERO
     1: N1=  8, N2=11163, Offset   +7.5uV

+1000V ZERO
     1: N1=  8, N2=12830, Offset  +30.5uV

-1000V ZERO
     1: N1=  8, N2=11155, Offset  +29.5uV

GAIN SHIFT
     +10:  -285.21uV
     +20:  -347.95uV
     +Hi:  -370.59uV
     -Hi:  +463.96uV
     -20:  +441.90uV
     -10:  +378.15uV

END OF INTERNAL CALIBRATION
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Offline e61_philTopic starter

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Re: Fluke 5440B Problems
« Reply #24 on: January 03, 2018, 12:01:09 am »
Quote from: Echo88 on January 02, 2018, 11:03:29 pm
How much time is needed for the 3458A to thermally stabilize at the high voltages? I know the 3458A will be a few ppm off at the high voltages.

I think one can't specify that exactly. We have two 3458A at work and both behave quite different at 1kV.
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