Test Equipment Anonymous (TEA) group therapy thread

[Kosmic]

It has nothing to do with volt-nuttery... He paid "New From the Distributor" price for that Siglent to have "one meter to rule them all". And now he has 3 high-end used meters that all agree (to certain definitions of the term) with each other... but NOT with that "brammy-spankin' new meter", and haven't since he got it.

I can see where that's a reasonable gripe. I'd have sent it back and requested they double-check it under warranty myself. Given that it's long past warranty period now, I agree with the argument that it should be re-cal'd by a Cal Lab & given a cal cert, so he has that "one cal'd meter to rule them all", which is what he paid the big bux for in the first place.

mnem
*huggles his 189 close*

What if the ref in the Siglent continue drifting after calibration ? Personally I would leave it on 24/7 (with screen off) to try to stabilize and age the voltage reference a little bit before sending it in for calibration. It's a shame it has not been done before building the meter. They could also use a better ref that doesn't really need aging.

That's all just armchair quarterbacking at this point. My suspicion is that the difference is more likely a matter of how this older generation of meters was compensated for circuit loading vs how this new generation is compensated, and that it may very well still have that discrepancy, and that discrepancy may very well not be linear.

Bottom line is that it is entirely possible for all 4 meters to read differently at this level of resolution and still be considered correct... it has to do with the process, not the numbers on the screen.

That is the major brain-fuckery of volt-nuttery: Uncertainly principle multiplied by the inherent inaccuracy of observation=Plato's Cave.

mnem
"Man with one watch always knows what time it is. Man with two is never sure." ~allegedly Chinese proverb

I'm talking about the voltage ref because tautech mentioned previously that the ref in the SDM was potentially drifting a little bit. See quote bellow.

It will be automated using a universal calibrator with a PC running a cal script but it's been reported SDM's drift a little until their references become suitably aged and stable so the user cal process has been developed for owners with decent references to make fine adjustments to accuracy.

Defpom tweaked his 3065X using one of IanJ's references that have been calibrated with a 8.5 digit DMM.
AFAIK it worked out just fine even though the adjustment process was still in the beta stages and Defpom provided some feedback to Siglent for them to polish it some.

[med6753]

What if the ref in the Siglent continue drifting after calibration ? Personally I would leave it on 24/7 (with screen off) to try to stabilize and age the voltage reference a little bit before sending it in for calibration. It's a shame it has not been done before building the meter. They could also use a better ref that doesn't really need aging.

Trust me, that voltage reference is aged. That Siglent has several hundred hours on it by now, maybe even more.

[med6753]

3456A Porn.  Beautiful construction. 






Front panel de-stickered. Bd reminder tag for 6.5 digits.  The 8505A has been removed and shelved in the bedroom.

And yes, that is very stable on top of the Type 535A. It's not going anywhere.

[factory]

There's another PM2421 on the german 'bay: https://www.ebay.de/itm/Philips-Digital-Multimeter-PM-2421-altes-Gerat/133651733259

Less than 16 hours to go and standing at less than 16 €.

I'd like to have those claws! 

And, of course, I had forgotten about it this morning. It went for 25.50 €. Had I remembered, I'd bid at least 30 € for it. Sigh. Perfectly fits the "Items you forget to bid sell for a low price" rule.

Same here. Forgot to bid on some nice Bourns 3296W 20R trimpots. Missed it about on two minutes.
They are gone for ca. 20 Euro.     

https://www.ebay.de/itm/402666716862

Don't cry guys, the buyer probably had a max bid of 50 Euro in there.

^{(Who am I kidding?)}

Looking at sold listings on ePay.de two have sold on auction last year for €50 each (one mislabelled as a 242) and no it wasn't me either, there does seem to be plenty of them around, four are listed in Europe at the moment from €55...      ..... to €240

David

[med6753]

And......I'm sick of this shit. 

[Kosmic]

I shall look out for a quiet one! 

Hp was selling a conversion kit at some point. My guess is that it was simply some wires and a aluminum plate that fit the hole in the back.

Kosmic,
Do you have more information about this change?
What exactly was the purpose - intention?

Regards, Frans

I don't know the reason. Probably to lower production cost and eliminate failure points.

Some pictures of my 3456a with the fan:





The fan main purpose of the fan is to cool down the digital section of the meter (the analog section is isolated). And on that section the only thing that can generate heat is the big transistor mounted on a tick bracket connected to the aluminum chassis. The transfo can probably produce a little bit of heat but that's generally not a problem.

I think they inherited that design from the 3455a and then realized they could drop the fan by moving the heat source outside the enclosure. It's mostly speculation from my part but I think it's plausible.

Look like the bridge rectifier was also moved at the back.



I need to check some caps on my 3456a, will probably try the modification at the same time.

[factory]

It has nothing to do with volt-nuttery... He paid "New From the Distributor" price for that Siglent to have "one meter to rule them all". And now he has 3 high-end used meters that all agree (to certain definitions of the term) with each other... but NOT with that "brammy-spankin' new meter", and haven't since he got it.

I can see where that's a reasonable gripe. I'd have sent it back and requested they double-check it under warranty myself. Given that it's long past warranty period now, I agree with the argument that it should be re-cal'd by a Cal Lab & given a cal cert, so he has that "one cal'd meter to rule them all", which is what he paid the big bux for in the first place.

mnem
*huggles his 189 close*

What if the ref in the Siglent continue drifting after calibration ? Personally I would leave it on 24/7 (with screen off) to try to stabilize and age the voltage reference a little bit before sending it in for calibration. It's a shame it has not been done before building the meter. They could also use a better ref that doesn't really need aging.

That's all just armchair quarterbacking at this point. My suspicion is that the difference is more likely a matter of how this older generation of meters was compensated for circuit loading vs how this new generation is compensated, and that it may very well still have that discrepancy, and that discrepancy may very well not be linear.

Bottom line is that it is entirely possible for all 4 meters to read differently at this level of resolution and still be considered correct... it has to do with the process, not the numbers on the screen.

That is the major brain-fuckery of volt-nuttery: Uncertainly principle multiplied by the inherent inaccuracy of observation=Plato's Cave.

mnem
"Man with one watch always knows what time it is. Man with two is never sure." ~allegedly Chinese proverb

Do we know what the input resistance is for all the 4 meters, sometimes they have a selectable high impedance option too. For example the HP 735A ref I have is loaded down by meters with a 10M input, the manual clearly states this.
One day I'll try and get several meters warmed up & play the same game, nothing I have here is calibrated.

David

[med6753]

Do we know what the input resistance is for all the 4 meters, sometimes they have a selectable high impedance option too. For example the HP 735A ref I have is loaded down by meters with a 10M input, the manual clearly states this.
One day I'll try and get several meters warmed up & play the same game, nothing I have here is calibrated.

David

I check for that too. Regardless of the input impedance if I'm going to connect 2 DMM's to same source I check first to make absolutely certain there is no interaction between them.

[med6753]

I need to check some caps on my 3456a, will probably try the modification at the same time.

I've already started a BOM to replace the electrolytics in the PSU only.

[Kosmic]

I need to check some caps on my 3456a, will probably try the modification at the same time.

I've already started a BOM to replace the electrolytics in the PSU only.

Someone made an adapter board for C5 (big 4,000uF at 15V)

https://oshpark.com/shared_projects/EVFWnnBD

[med6753]

I need to check some caps on my 3456a, will probably try the modification at the same time.

I've already started a BOM to replace the electrolytics in the PSU only.

Someone made an adapter board for C5 (big 4,000uF at 15V)

https://oshpark.com/shared_projects/EVFWnnBD

Thanks. I didn't realize that was going to be a hassle. I'm going to order the adapter. 

Update...ordered.

[factory]

Quick update on the HP 5243L counter, the oven controller section is faulty as it doesn't turn the crystal oven heater on at all.
Trouble is now I've done some testing & comparison with a parts mule 5245L (missing all removable boards) I've come to the conclusion the fault is within the oven assembly itself. I've posted more to the 5245L thread here as it also had oven problems too;
https://www.eevblog.com/forum/repair/repair-of-hp-5245l-nixie-frequency-counter/msg3455940/#msg3455940

For anyone else with a 5243L, 5244L or 5245L series counter with the 5243A-69A crystal oven assembly, it's a good idea to add a fuse to prevent the transformer from burning out if the oven heater fails S/C, as they sometimes do.


Before & after fuse mod.



David

[Saskia]

ott graphics card arrived today. However the seal of the box was broken and the antistatic bag was torn.
Asked the dealer to clarify.

[mnementh]

mnem

[Specmaster]

Both the 3456A and 8505A have been on for approx 18 hours and I have some interesting results.

Test set-up. One of the AD584-M's powered by USB and powered continuously during the test. It was set to the indicated 9.99691V. That voltage is achieved at 25 C. I noticed during the Winter months that both my AD584-M's read lower due to ambient 21 C and take a while to warm up.

Results: Within approx 2 hours the 3456A stabilized and didn't vary all night. The 8505A did not fair well. It started out agreeing with the 3456A within one or two digits but as the test progressed it's measurement kept continuing to drift lower and lower and it wasn't until maybe 12 hours into the test that it stopped. The 3465A stabilized at 9.99693V to 95. The 8505A finally stopped drifting at 9.99676V to 78. In real world applications that doesn't mean a hill of beans. But to a volt-nut that's tragic. And if you compare it to the other three AD584-M voltages it begins to tell a story....


AD584-M         3456A            8505A

2.50066V          2.50061V       2.50062V

4.99794V          4.99792V       4.99790V

7.50011V          7.50012V       7.50000V

You can clearly see a pattern here. As the voltage increases the 8505A becomes more and more inaccurate.

And as further proof that something is amiss with the 8505A. Here is the other AD584-M
 
AD584-M         3456A             8505A

2.49937V          2.49938V       2.49938V 

5.00030V          5.00034V       5.00030V

7.50042V          7.50050V       7.50038V     

10.00096V       10.00108V      10.00094V

I don't have the ability to perform a full calibration on the 8505A and I don't think it's worth the effort and expense to send it to a cal lab. And unfortunately there are no cal labs within reasonable driving distance. But I suspect there's more going on here than just a calibration. The non-linear delta as the voltage increases is very suspicious. And in order to troubleshoot this DMM you need an extender board which is almost impossible to find. So my choices are sell this 8505A as a parts only unit or just quietly retire it and hope that one day an extender board shows up. I haven't decided what to do yet.

And as a side note. Speaking of the Siglent SDM 3055. I've decided that when the budget allows I'm going to sent it in for a full calibration rather than attempt to “tweak” it myself. And here it is measuring the same 9.99691V after it's been powered up for over 12 hours. I would expect at least a reading of 9.9968V or 69. And it's off at least that much on all the other references. 

Very interesting, and it's plain to see that you are not just teetering on the edge of that rabbit hole but rapidly sliding head first down it and for what other reason than OCD, I mean we are just talking of micro volts, when was the last time you had to measure or adjust something to that level  Bugs Bunny is waiting at the bottom of rabbit hole and when you get there, he'll ask you only the way he can "Err whats up Doc?"

It has nothing to do with volt-nuttery... He paid "New From the Distributor" price for that Siglent to have "one meter to rule them all". And now he has 3 high-end used meters that all agree (to certain definitions of the term) with each other... but NOT with that "brammy-spankin' new meter", and haven't since he got it.

I can see where that's a reasonable gripe. I'd have sent it back and requested they double-check it under warranty myself. Given that it's long past warranty period now, I agree with the argument that it should be re-cal'd by a Cal Lab & given a cal cert, so he has that "one cal'd meter to rule them all", which is what he paid the big bux for in the first place.

mnem
*huggles his 189 close*

Totes agree 100% about the Siglent, I was referring to the Fluke and HP. The Siglent ought to have agreed with the AD584's in the first instance, but even then its only a very tiny amount (uV) off the mark and given the type of thing its used for, old scopes just don't demand that level calibration. The other 3,4 and 5 digit meters are IIRC "dead nuts"

The only 6.5 digit meter that I'll end up with is my 1905A, my 2 Solartrons are going, I don't need that number of digits as I never look past the mV anyway, so they might as well be funding other TEA item acquisitions. I have plenty of 3, 4 and 5.5 digit meters, including 4.5 and 5.5 digit handhelds.

[Robert763]

<SNIP>

That's all just armchair quarterbacking at this point. My suspicion is that the difference is more likely a matter of how this older generation of meters was compensated for circuit loading vs how this new generation is compensated, and that it may very well still have that discrepancy, and that discrepancy may very well not be linear.

Bottom line is that it is entirely possible for all 4 meters to read differently at this level of resolution and still be considered correct... it has to do with the process, not the numbers on the screen.

That is the major brain-fuckery of volt-nuttery: Uncertainly principle multiplied by the inherent inaccuracy of observation=Plato's Cave.

mnem
"Man with one watch always knows what time it is. Man with two is never sure." ~allegedly Chinese proverb

There is NO compensation for circuit loading in any of these meters. They measure what appears at the terminals regardless of the load they place on the external voltage. The meters are in parallel so differences in input impedance is irrelevent. The impedance should not matter with a modern Voltage standard anyway because it's imedance is tiny compared to the meter.

The Uncertainly Principle has nothing to do with Voltage measurement, Time measurement, yes.

[Saskia]

mnem

Well, the serial numbers of the card and the box match. The card still may be unused. However for a card of this particular cost I would very much like to break the seal myself.

Unless I knowingly buy it open box. That would be a completely different matter.

[Ice-Tea]

ott graphics card arrived today. However the seal of the box was broken and the antistatic bag was torn.
Asked the dealer to clarify.

Should they decide to send you an additional card to make up for the screwup, consider your friendly neighbour if you must get rid of the exces card...

Also: I'd give this a B+ for packaging.

[Specmaster]

Do we know what the input resistance is for all the 4 meters, sometimes they have a selectable high impedance option too. For example the HP 735A ref I have is loaded down by meters with a 10M input, the manual clearly states this.
One day I'll try and get several meters warmed up & play the same game, nothing I have here is calibrated.

David

I check for that too. Regardless of the input impedance if I'm going to connect 2 DMM's to same source I check first to make absolutely certain there is no interaction between them.

Yeah, agree, I do the same thing myself when checking mine with each other.

[AVGresponding]

Very interesting, and it's plain to see that you are not just teetering on the edge of that rabbit hole but rapidly sliding head first down it and for what other reason than OCD, I mean we are just talking of micro volts, when was the last time you had to measure or adjust something to that level  Bugs Bunny is waiting at the bottom of rabbit hole and when you get there, he'll ask you only the way he can "Err whats up Doc?"

If you go back and read what I wrote I stated in the real world this doesn't mean squat. Almost all the equipment we deal with could not care less about a few microvolts. The point here is if we have the tools to measure something it damn sure better be accurate. I had noticed that the 8505A was drifting over time but I couldn't tell if it was the reference or the DMM. I now have my answer. The 3456A clearly shows that once the reference is warmed up it's stable and the Fluke has the issue.

Same with the Siglent. It never agreed with the two Fluke 8800A's that track each other perfectly. The Siglent tracked consistently low. Yes, that bugged me from day one because it's inaccurate. (and now with the 3456A it further proves it is inaccurate) Tautech sent me the procedure for tweaking it and when I get a chance I'm going to give it a try.

I'm a little unclear about what you mean by the 8505 drifting over time.

Do you mean over a period of months, or over the 12 hours warm up?

In the former, after having looked at the specs, it would seem to be probably well inside the specified limits.

If the latter, the manual states the specified accuracy is achieved after a 4 hour warm up, and within 1 hour of zeroing. I wonder, did you zero it within an hour of each reading, or just leave it connected permanently?

If the reference is self heating I guess maybe the heater is past its best, though I've no idea what temperature you like in your house, maybe the ambient is lower than the Fluke likes?



I found it slightly surprising that some Siglents came with un-aged or not fully aged references, I thought it was standard practice to use properly aged, and sometimes even selected, references.

[Ice-Tea]

One of you lovely people wouldn't happen to know where to get a few button caps for this series?

[McBryce]

One of you lovely people wouldn't happen to know where to get a few button caps for this series?

Out of a 3D printer?

McBryce.

[Ice-Tea]

One of you lovely people wouldn't happen to know where to get a few button caps for this series?

Out of a 3D printer?

McBryce.

Kids these days 

[bd139]

One of you lovely people wouldn't happen to know where to get a few button caps for this series?

https://www.keysight.com/my/partDetail/E3630-40007

Phone up your local rep

[Ice-Tea]

One of you lovely people wouldn't happen to know where to get a few button caps for this series?

https://www.keysight.com/my/partDetail/E3630-40007

Phone up your local rep

Heh. I know they have a comprehensive spare part catalog but I never ordered from them, TBH.