Author Topic: Keithley 614 electrometer  (Read 4875 times)

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Offline feedback.loop

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Keithley 614 electrometer
« on: November 28, 2015, 06:45:52 am »
Check out this repair video of a Keithley 614 electrometer from mid-1980s. 4.5 digit meter with 50TOhm input impedance, 20pA current range, and 200GOhm resistance range.


 
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Offline Vgkid

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Re: Keithley 614 electrometer
« Reply #1 on: November 28, 2015, 05:44:42 pm »
Thanks for the video, good job on those repairs/upgrades. Surprised that the switches can case such interesting issues.
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Online TiN

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Re: Keithley 614 electrometer
« Reply #2 on: November 28, 2015, 07:49:08 pm »
Great job on repair and calibration. Congratz!
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Online HighVoltage

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Re: Keithley 614 electrometer
« Reply #3 on: November 28, 2015, 11:32:33 pm »
Very impressive repair of the 614.
Thanks for sharing.

I am also surprised of how accurate the little DATEL DVC-8500A is.
May be you can open that one and show us what is inside.

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Offline eas

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Re: Keithley 614 electrometer
« Reply #4 on: November 29, 2015, 04:07:39 am »
Thanks!  I have one of these that I got fairly cheap. I didn't need it, but I figured I'd learn something from it.

So far the main thing I've learned is that I have a hard time with paying $100+ for a triax lead for a meter I paid $50 for :)
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Offline feedback.loop

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Re: Keithley 614 electrometer
« Reply #5 on: November 29, 2015, 10:42:47 am »
I am also surprised of how accurate the little DATEL DVC-8500A is.
May be you can open that one and show us what is inside.

Yes, a nice instrument. I have a pile of projects waiting, and not enough time, and I want to sell the thing since I got myself 6 digit Fluke 341A (see another repair video). I will keep this in mind. Perhaps one day...

Here is a description of this DVC-8500:
The DVC-8500 is a low cost 4 1/2 digit voltage reference source with a full-scale output range of +19.999 Volts to =19.999 Volts in 1 millivolt steps. The calibrator features high performance for such a small, low-cost instrument. An active buffered output amplifier provides very low output impedance and up to 25 milliamps output current. An oven-stabilized zener diode internal reference provides an overall output accuracy of ±500 uV and ±25 ppm of the setting with zero drift of ±5 uV/°C and full-scale drift of 4 ppm/°C max. Output is set by unique front-panel lever switches which provide rapid, positive contact adjustment. Voltage outputs may be continuously varied within ±1.5 millivolts of selected readings by using a front panel vernier control. The DVC-8500 output is available from both front panel banana jacks and rear panel gld-plated connector fitted with lug terminals. The rear connector has sense feedback inputs to reduce errors caused by cable resistance. A front-panel LED overload lamp lights if the output exceeds 25 mA and current limiting occurs at 70 mA output. The output circuit accepts up to ±25 mA source or sink current at rated accuracy. The rear connector also includes a low-Z output of the +10 Volt reference source with 5 mA maximum. Powered by a choice of 100, 115 or 230 VAC ±10% and 47 to 440 Hz at 10 watts, the DVC-8500 offers transformer isolation up to ±300V dc. Output line rejection is within ±50 microvolts of zero. The black-anodized extruded aluminum housing provides excellent shielding from electrical noise. The small size and light-weight design of the DVC-8500 makes it an ideal portable instrument for a technician's repair kit. When mounted on its bench-top tilt stand, the DVC-8500 uses very little space and can be positioned close to test circuits.
« Last Edit: November 29, 2015, 04:37:16 pm by feedback.loop »
 

Online HighVoltage

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Re: Keithley 614 electrometer
« Reply #6 on: November 29, 2015, 11:55:17 pm »
Powered by a choice of 100, 115 or 230 VAC ±10% and 47 to 440 Hz at 10 watts, the DVC-8500 offers transformer isolation up to ±300V dc.

The one I see on ebay.com has only a label for 115V
Can you switch them internally to 230V AC or do you need a new transformer?
If you know.
Although I have 115 V in my lab, I rather prefer a 230V unit.
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Offline feedback.loop

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Re: Keithley 614 electrometer
« Reply #7 on: November 30, 2015, 04:42:09 am »
Powered by a choice of 100, 115 or 230 VAC ±10% and 47 to 440 Hz at 10 watts, the DVC-8500 offers transformer isolation up to ±300V dc.

The one I see on ebay.com has only a label for 115V
Can you switch them internally to 230V AC or do you need a new transformer?
If you know.
Although I have 115 V in my lab, I rather prefer a 230V unit.

I opened it up. See the photos. It seems to me that it is a factory option - a matter of swapping the transformer.
By the way, the voltage reference is LM399.

https://drive.google.com/file/d/0B3NWgPtazb_tVUYzaGExaTczbFk
https://drive.google.com/file/d/0B3NWgPtazb_taWlLUzB4OVRMOTg
https://drive.google.com/file/d/0B3NWgPtazb_takRfSEhOTjFqa2M
 

Offline eas

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Re: Keithley 614 electrometer
« Reply #8 on: November 30, 2015, 06:10:06 am »
I was confused for a moment about the LM399. I didn't remember seeing one in my 614. Then I realized you were talking about the VRef in the DATEL.

(which I only mention in case someone else has the same confusion)
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Offline feedback.loop

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Re: Keithley 614 electrometer
« Reply #9 on: November 30, 2015, 06:38:43 am »
I was confused for a moment about the LM399. I didn't remember seeing one in my 614. Then I realized you were talking about the VRef in the DATEL.

(which I only mention in case someone else has the same confusion)

Speaking of the voltage reference in Keithley 614, I didn't look at it in the video at all since it was buried somewhere on the front panel board, which I didn't remove. In the manual it is mentioned as DZ-58 6.35V zener.
 

Online HighVoltage

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Re: Keithley 614 electrometer
« Reply #10 on: November 30, 2015, 07:19:47 am »
The Keithley 614 and the Datel reference are more impressive that I would have expected.

Thanks for the feedback on the transformer and the great pictures.
It should be simple to switch them over to 230V, if I find one for a reasonable price.
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Offline dacman

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Re: Keithley 614 electrometer
« Reply #11 on: November 30, 2015, 02:17:30 pm »
DVC-8500A: 115 Vac
DVC-8500E: 230 Vac
DVC-8500J: 100 Vac
 

Offline eas

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Re: Keithley 614 electrometer
« Reply #12 on: November 30, 2015, 07:31:37 pm »
I was confused for a moment about the LM399. I didn't remember seeing one in my 614. Then I realized you were talking about the VRef in the DATEL.

(which I only mention in case someone else has the same confusion)

Speaking of the voltage reference in Keithley 614, I didn't look at it in the video at all since it was buried somewhere on the front panel board, which I didn't remove. In the manual it is mentioned as DZ-58 6.35V zener.

I snapped a photo of the front panel board when I was looking over my 614. I'm guessing it is the bright red device and that DZ-58 is an internal Keithley part number.
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Offline wiss

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Re: Keithley 614 electrometer
« Reply #13 on: November 30, 2015, 07:43:18 pm »
I am also surprised of how accurate the little DATEL DVC-8500A is.
May be you can open that one and show us what is inside.

Yes, a nice instrument. I have a pile of projects waiting, and not enough time, and I want to sell the thing since I got myself 6 digit Fluke 341A (see another repair video). I will keep this in mind. Perhaps one day...

Here is a description of this DVC-8500:
The DVC-8500 is a low cost 4 1/2 digit voltage reference source with a full-scale output range of +19.999 Volts to =19.999 Volts in 1 millivolt steps. The calibrator features high performance for such a small, low-cost instrument. An active buffered output amplifier provides very low output impedance and up to 25 milliamps output current. An oven-stabilized zener diode internal reference provides an overall output accuracy of ±500 uV and ±25 ppm of the setting with zero drift of ±5 uV/°C and full-scale drift of 4 ppm/°C max. Output is set by unique front-panel lever switches which provide rapid, positive contact adjustment. Voltage outputs may be continuously varied within ±1.5 millivolts of selected readings by using a front panel vernier control. The DVC-8500 output is available from both front panel banana jacks and rear panel gld-plated connector fitted with lug terminals. The rear connector has sense feedback inputs to reduce errors caused by cable resistance. A front-panel LED overload lamp lights if the output exceeds 25 mA and current limiting occurs at 70 mA output. The output circuit accepts up to ±25 mA source or sink current at rated accuracy. The rear connector also includes a low-Z output of the +10 Volt reference source with 5 mA maximum. Powered by a choice of 100, 115 or 230 VAC ±10% and 47 to 440 Hz at 10 watts, the DVC-8500 offers transformer isolation up to ±300V dc. Output line rejection is within ±50 microvolts of zero. The black-anodized extruded aluminum housing provides excellent shielding from electrical noise. The small size and light-weight design of the DVC-8500 makes it an ideal portable instrument for a technician's repair kit. When mounted on its bench-top tilt stand, the DVC-8500 uses very little space and can be positioned close to test circuits.

I have 2 DVC-8500 at work, I was not particularly impressed by them, very tricky to adjust, maybe good for 4 digits as I remember...
 

Online HighVoltage

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Re: Keithley 614 electrometer
« Reply #14 on: December 01, 2015, 01:29:46 am »
I have 2 DVC-8500 at work, I was not particularly impressed by them, very tricky to adjust, maybe good for 4 digits as I remember...
I was only intrigued by the small size and 1 mV setting for the full scale -19 to +19 V
It is definitely not a metrology reference for today's digital bench meters, but sometimes I have to check and verify 4 1/2 digit handheld meters in the production and this one could be handy.

DVC-8500A: 115 Vac
DVC-8500E: 230 Vac
DVC-8500J: 100 Vac
Thanks for this. I will keep looking for the 230V version.
 
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Offline PedroDaGr8

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Re: Keithley 614 electrometer
« Reply #15 on: December 01, 2015, 03:10:29 am »
I was confused for a moment about the LM399. I didn't remember seeing one in my 614. Then I realized you were talking about the VRef in the DATEL.

(which I only mention in case someone else has the same confusion)

Speaking of the voltage reference in Keithley 614, I didn't look at it in the video at all since it was buried somewhere on the front panel board, which I didn't remove. In the manual it is mentioned as DZ-58 6.35V zener.

I snapped a photo of the front panel board when I was looking over my 614. I'm guessing it is the bright red device and that DZ-58 is an internal Keithley part number.

According to the Keithley 175 manual, DZ-58 is a 1N4577 zener (+/-0.002%/oC max Tco).
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Offline wiss

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Re: Keithley 614 electrometer
« Reply #16 on: December 02, 2015, 08:41:26 am »
I have 2 DVC-8500 at work, I was not particularly impressed by them, very tricky to adjust, maybe good for 4 digits as I remember...
I was only intrigued by the small size and 1 mV setting for the full scale -19 to +19 V
It is definitely not a metrology reference for today's digital bench meters, but sometimes I have to check and verify 4 1/2 digit handheld meters in the production and this one could be handy.

Just ran into this ebay-sale: http://www.ebay.com/itm/KEITHLEY-197-MICROVOLT-MULTIMETR-BATTERIES-OPERATED-W-MANUALS-SCHE-wbr-MATIC-PROBES-/181945977996?&_trksid=p2056016.m2518.l4276
Obviously fake or a very lucky shoot! No way the Datel is that accurate!  :-DD  :popcorn:

 

Offline PedroDaGr8

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Re: Keithley 614 electrometer
« Reply #17 on: December 02, 2015, 09:07:58 am »
I have 2 DVC-8500 at work, I was not particularly impressed by them, very tricky to adjust, maybe good for 4 digits as I remember...
I was only intrigued by the small size and 1 mV setting for the full scale -19 to +19 V
It is definitely not a metrology reference for today's digital bench meters, but sometimes I have to check and verify 4 1/2 digit handheld meters in the production and this one could be handy.

Just ran into this ebay-sale: http://www.ebay.com/itm/KEITHLEY-197-MICROVOLT-MULTIMETR-BATTERIES-OPERATED-W-MANUALS-SCHE-wbr-MATIC-PROBES-/181945977996?&_trksid=p2056016.m2518.l4276
Obviously fake or a very lucky shoot! No way the Datel is that accurate!  :-DD  :popcorn:

Notice, that is the only one that they showed the DATEL too.
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Offline Octane

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Re: Keithley 614 electrometer
« Reply #18 on: February 22, 2018, 03:25:26 pm »
Hi,

Has anybody the schematic and the PCB component locations drawing?
It seems that it should be in the manual, but there are only lists, no drawings in the 48 pages.

Thanks,
Michael
 

Offline feedback.loop

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Re: Keithley 614 electrometer
« Reply #19 on: February 22, 2018, 04:48:06 pm »
Hi,

Has anybody the schematic and the PCB component locations drawing?
It seems that it should be in the manual, but there are only lists, no drawings in the 48 pages.

Thanks,
Michael

What manual are you talking about?
There is a link in the video description:
http://exodus.poly.edu/~kurt/manuals/manuals/Keithley/KEI%20614%20Instruction.pdf
 
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Offline Octane

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Re: Keithley 614 electrometer
« Reply #20 on: February 23, 2018, 12:38:20 am »
Thanks feedback! All the manuals that I found googling around only had 48 pages. I obviously am lacking the right googling skills. Thanks again!

Michael
 


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