Author Topic: New Keithley DMM6500 and now DAQ6510  (Read 296671 times)

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Offline optotester

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1375 on: September 20, 2021, 08:58:47 am »
Hi all,

Just bought DMM6500 (manufactured in Mar/Apr 2021) and looks like hardware quality did not really improve. I was hoping that two years after release the quality issues would have been fixed. Transformer 'hum' is there but the most annoying is really the screen. If put on a bench (so viewing from slightly above) it is almost impossible to read text due to reflections in the TFT layers...
Are all units affected the same or am I just unlucky ? I am considering switching to 34465A instead although price is different and it seems to have less functions.

Regards
« Last Edit: September 20, 2021, 09:23:54 am by optotester »
 

Offline voltsandjolts

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1376 on: September 20, 2021, 09:17:12 am »
I have the DMM flat on my workbench, under my monitor. Sitting at my desk, I can read it clearly, no problem.
It does hum slightly, if I listen for it, but doesn't annoy me. Seems like this varies between units.
 

Offline LordXaos

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1377 on: September 20, 2021, 09:28:02 am »
I did have it standing on my bench and nowadays have it up on a shelve, with no viewing issues whatsoever - but I did remove the protective plastic.
 

Offline optotester

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1378 on: September 20, 2021, 09:36:55 am »
When I unpacked it I thought, ok, it is just the protective plastic but then I removed it a little and noticed that display was looking equally bad without it (so I did not peel it off completely and just put everything back in the box).
Right now I hesitate between:
- Returning to seller and buying 34465A (but it is much more expensive)
- Sending for warranty to Tektronix and hope that everything will be fine afterwards
 

Offline Kleinstein

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1379 on: September 20, 2021, 09:49:46 am »
The reflections of the screen are not nice, as the limit the viewing angle for small details. The large main numbers shoud still be OK though.
I think this is more like a weakness in design and nothing a warranty rapair could fix. It just is this way on all units. I would be defect only if they for some reason forgot an anti reflective coating. So the question is, if other units are also that way.
Without the protective foil it may be a little better, though likely not much. Refelxtions and fingerprints are kind of the price you pay for a touchscreen.
 

Offline HighVoltage

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1380 on: September 20, 2021, 10:12:29 am »
Although I find the screen of the DMM7510 a little better to read in comparison, I really have nothing to complain about the DMM6500 screens readability.
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Offline optotester

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1381 on: September 20, 2021, 10:41:37 am »
Thank you all for the feedbacks  :). I am not that picky, I am actually very satisfied with my other bench equipment (SDS1104X-E and SPD3303X-E) even if they have drawbacks too (like the bezel of the oscilloscope hiding the first line and fan noise).
One of the issue is that my lab room is quite small so the bench is less that 80cm deep. Although the previous picture viewing angle is a bit extreme, real use case is almost as bad as that. Keysight DMM being shorter it may help a lot for readability.

Or maybe DMM6500 can be fully controlled with a mouse from the web UI ? If it is the case, then maybe it could be ok to keep it ? ("hum" noise is not that much of an issue, I can take the plug off anyway).
« Last Edit: September 20, 2021, 10:44:03 am by optotester »
 

Offline KedasProbe

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1382 on: September 20, 2021, 11:06:37 am »
Or maybe DMM6500 can be fully controlled with a mouse from the web UI ? If it is the case, then maybe it could be ok to keep it ? ("hum" noise is not that much of an issue, I can take the plug off anyway).
With digitizing you could get update problems on the WebUI also multi touch for zooming isn't an option.

I don't have any viewing angle issues. I use the WebUI just to see the graphs bigger.
Not everything that counts can be measured. Not everything that can be measured counts.
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Offline Hydron

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1383 on: September 20, 2021, 11:29:09 am »
I've had two different units here with widely spaced build dates - the earlier one had a bad transformer hum (bad enough to be sent back for transformer replacement), but the screens were pretty similar, and both showed the issue at the same specific angle.

I also wish that they had managed to do better with the panel, but it's still usable and I decided to put up with it in exchange for the significantly better price and features vs the Keysight equivalents. This is especially true now that Keysight has decided to not support anyone in europe who isn't a VAT registered business - I would have been completely fucked with the KS even for calibration once the warranty ended. The Tek salesman on the other hand managed to dig up an ex-demo unit for me to save money on when I told him I was buying as a hobbyist (ex-demo being the reason for the unit being older - the other was a new one I was loaned due to brexit-related delays in shipping/servicing).
 

Offline thm_w

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1384 on: September 20, 2021, 11:26:59 pm »
I never noticed any hum people were discussing here. Yesterday I picked up the unit while powered on and when it was at an angle it started to hum very loudly, until horizontal again.
Which makes me think it can be an internal mechanical issue, that could easily be fixed with some rubber washers, etc? Of course if its a new unit and you don't want to take it apart that is understandable.

As for the LCD issue, do what you can to angle it upwards or set it at eye height.
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Offline Hydron

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1385 on: September 22, 2021, 12:26:34 am »
The hum is a combination of running the transformer a little closer than is ideal to saturation and not having enough damping for noise/vibrations. When I compared the noisy vs quieter units they both pulled similar magnetising current, so it seems that the improvements to the revised transformer design are mostly mechanical.

Note that my mains runs close to 250V @ 50Hz so is pretty much worst case for saturation - both 60Hz and lower mains voltage would significantly reduce the issue, though the revised transformer is quite acceptable from a noise perspective.
 
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Offline KaneTW

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1386 on: September 24, 2021, 03:07:44 am »
The hum on my Keithley is barely present after an RMA but it does scale with line voltage.
 

Offline E-Design

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1387 on: September 24, 2021, 11:36:03 am »
The hum issue is one that has been improving over time but proven quite difficult to resolve completely.

The transformer supports both the DMM and DAQ model. As such, there are 2 transformers that are present in the instrument, 1 for the DMM and 1 for the DAQ that powers the switch modules.
In order to fit both of these transformers into the instrument (for both models), they required being bolted together in a metal frame that is affixed to the chassis.

The transformer design and housing is the way it is completely for cost and mechanical reasons. However, this has actually made the hum problem worse.
It turns out that this metal bracket actually vibrates and sort of resonates the sound not only from the natural transformer vibration but introduces larger harmonics of it.

The transformers are *double* dipped in varnish AND the metal bracket has an epoxy fillet along the perimeter of the mounting to help dampen vibrations. Yet still, some hum can be heard in some cases.

The factory has some controls in place to make sure it is not "too bad" -- again though, this is subjective!

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Offline HighVoltage

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1388 on: September 24, 2021, 02:34:46 pm »
I must have been very lucky because my DMM6500 has no hum at all.

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Offline Hydron

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1389 on: September 24, 2021, 09:25:43 pm »
I must have been very lucky because my DMM6500 has no hum at all.
I'm surprised that you're saying "no hum at all", but if your mains voltage is on the low side (especially if you've got it in the 240V setting) then it could be minimal - I found a fairly strong dependence on mains voltage, with a ~10% drop making a major reduction in noise. Not unexpected given the physics involved, just a shame the design was so on-the-limit for saturation in high-line 240V/50Hz areas.

E-Design - interesting to hear about the reason for the double unit; is the second (DAQ supply) transformer actually used in a DMM6500? Or just when an optional scanner card is plugged in?
 

Online skander36

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1390 on: September 24, 2021, 10:43:48 pm »
I must have been very lucky because my DMM6500 has no hum at all.
I'm doubt. Maybe you have in the same room other sources of hum which your mind is used to ignore.
Put the meter in a quiet room and see.
For me it is the only and most terrible source of hum from my bench.
Siglent SDM 3065 has also a linear power source in standby but it doesn't make any noise.
 

Offline rcjoy

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1391 on: September 24, 2021, 11:57:03 pm »

No transformer hum at all on my 2019 DMM6500.

Also, I keep the unit at eye-height on my instrument stack, and the display looks perfect.  It does wash out somewhat at extreme angles, but that has not been a problem for me.
I'm really happy with the unit.
 

Offline E-Design

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1392 on: September 25, 2021, 12:47:11 am »
I must have been very lucky because my DMM6500 has no hum at all.
I'm surprised that you're saying "no hum at all", but if your mains voltage is on the low side (especially if you've got it in the 240V setting) then it could be minimal - I found a fairly strong dependence on mains voltage, with a ~10% drop making a major reduction in noise. Not unexpected given the physics involved, just a shame the design was so on-the-limit for saturation in high-line 240V/50Hz areas.

E-Design - interesting to hear about the reason for the double unit; is the second (DAQ supply) transformer actually used in a DMM6500? Or just when an optional scanner card is plugged in?

Yes, 1 transformer is for analog supplies only (both models) and the second one powers the digital system (on both models and also the scanner cards)
These 65xx models are the upgrade for the Model 2700 and 2701 and the transformer design was leveraged from those models. However, those older models do not have a dual arrangement with the bracket configuration.

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Offline cgroen

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1393 on: September 25, 2021, 06:51:36 am »
I got 2 DMM6500, also no hum (230VAC). Both are from 2019
 

Offline Hydron

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1394 on: September 26, 2021, 12:02:15 am »
The older of the two (2019 I think) I had was totally unacceptable - the whole thing was vibrating when you touched it, let alone the noise!
RMA'd it and it got sorted, came back similar to the newer unit (the loner which then went back). No significant change in magnetising current though.
« Last Edit: September 26, 2021, 12:07:14 am by Hydron »
 

Offline mawyatt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1395 on: September 26, 2021, 02:46:23 pm »
Looked around and couldn't find anything on how the DMM6500 measures RMS AC. Does anyone know how this is done, an analog RMS chip converter, or like the KS3446x using the computed values from the ADC?

Believe the Siglent SDM3065X using an analog RMC converter chip and not a computed value like the KS.

Also, how does the DMM6500 behave with high crest factor waveforms?

Thanks for the reply.

Best,
« Last Edit: September 26, 2021, 04:06:17 pm by mawyatt »
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Offline E-Design

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1396 on: September 26, 2021, 11:48:38 pm »
Looked around and couldn't find anything on how the DMM6500 measures RMS AC. Does anyone know how this is done, an analog RMS chip converter, or like the KS3446x using the computed values from the ADC?

Believe the Siglent SDM3065X using an analog RMC converter chip and not a computed value like the KS.

Also, how does the DMM6500 behave with high crest factor waveforms?

Thanks for the reply.

Best,

The digitizer hardware is used to capture the waveform and then the RMS value is calculated. There is no RMS converter IC present. As far as high crest factor performance,  IIRC, it was mostly comparable to the IC solution. It might be slightly better or worse in a few particular cases. Consult the datasheet for details.
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Offline MegaVolt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1397 on: October 21, 2021, 08:53:41 pm »
New firmware 1.7.10

The captions on the charts have become beautiful.

 
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Offline RBBVNL9

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1398 on: October 22, 2021, 06:55:53 am »
Quote
New firmware 1.7.10
The captions on the charts have become beautiful.

Nice! I see they also solved one issue that I reported a while ago to Keithley (and shared here on the forum), which was a crash when hitting the print screen button twice within 10 seconds or so. 


 

Offline MegaVolt

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Re: New Keithley DMM6500 and now DAQ6510
« Reply #1399 on: October 22, 2021, 07:04:20 am »
Nice! I see they also solved one issue that I reported a while ago to Keithley (and shared here on the forum), which was a crash when hitting the print screen button twice within 10 seconds or so.
Can you tell me where you wrote to report the problem? My messages have been ignored for years.
 


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