Keithley 614 electrometer - Page 1
Forum section: electronics / testgear

author: feedback.loop
author_rank: Frequent Contributor
timestamp: November 27, 2015, 07:45:52 pm
content: 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.https://youtu.be/txH6EpqN5V0

author: Vgkid
author_rank: Super Contributor
timestamp: November 28, 2015, 06:44:42 am
content: Thanks for the video, good job on those repairs/upgrades. Surprised that the switches can case such interesting issues.

author: TiN
author_rank: Super Contributor
timestamp: November 28, 2015, 08:49:08 am
content: Great job on repair and calibration. Congratz!

author: HighVoltage
author_rank: Super Contributor
timestamp: November 28, 2015, 12:32:33 pm
content: 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.

author: eas
author_rank: Frequent Contributor
timestamp: November 28, 2015, 05:07:39 pm
content: 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

author: feedback.loop
author_rank: Frequent Contributor
timestamp: November 28, 2015, 11:42:47 pm
content: Quote from: HighVoltage on November 28, 2015, 12:32:33 pmYes, 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.

author: HighVoltage
author_rank: Super Contributor
timestamp: November 29, 2015, 12:55:17 pm
content: Quote from: feedback.loop on November 28, 2015, 11:42:47 pmThe one I see on ebay.com has only a label for 115VCan 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.

author: feedback.loop
author_rank: Frequent Contributor
timestamp: November 29, 2015, 05:42:09 pm
content: Quote from: HighVoltage on November 29, 2015, 12:55:17 pmI 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_tVUYzaGExaTczbFkhttps://drive.google.com/file/d/0B3NWgPtazb_taWlLUzB4OVRMOTghttps://drive.google.com/file/d/0B3NWgPtazb_takRfSEhOTjFqa2M

author: eas
author_rank: Frequent Contributor
timestamp: November 29, 2015, 07:10:06 pm
content: 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)

author: feedback.loop
author_rank: Frequent Contributor
timestamp: November 29, 2015, 07:38:43 pm
content: Quote from: eas on November 29, 2015, 07:10:06 pmSpeaking 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.

author: HighVoltage
author_rank: Super Contributor
timestamp: November 29, 2015, 08:19:47 pm
content: 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.

author: dacman
author_rank: Frequent Contributor
timestamp: November 30, 2015, 03:17:30 am
content: DVC-8500A: 115 VacDVC-8500E: 230 VacDVC-8500J: 100 Vac

author: eas
author_rank: Frequent Contributor
timestamp: November 30, 2015, 08:31:37 am
content: Quote from: feedback.loop on November 29, 2015, 07:38:43 pmI 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.

author: wiss
author_rank: Frequent Contributor
timestamp: November 30, 2015, 08:43:18 am
content: Quote from: feedback.loop on November 28, 2015, 11:42:47 pmI 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...

author: HighVoltage
author_rank: Super Contributor
timestamp: November 30, 2015, 02:29:46 pm
content: Quote from: wiss on November 30, 2015, 08:43:18 amI was only intrigued by the small size and 1 mV setting for the full scale -19 to +19 VIt 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.Quote from: dacman on November 30, 2015, 03:17:30 amThanks for this. I will keep looking for the 230V version.

author: PedroDaGr8
author_rank: Super Contributor
timestamp: November 30, 2015, 04:10:29 pm
content: Quote from: eas on November 30, 2015, 08:31:37 amAccording to the Keithley 175 manual, DZ-58 is a 1N4577 zener (+/-0.002%/oC max Tco).

author: wiss
author_rank: Frequent Contributor
timestamp: December 01, 2015, 09:41:26 pm
content: Quote from: HighVoltage on November 30, 2015, 02:29:46 pmJust 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.l4276Obviously fake or a very lucky shoot! No way the Datel is that accurate!

author: PedroDaGr8
author_rank: Super Contributor
timestamp: December 01, 2015, 10:07:58 pm
content: Quote from: wiss on December 01, 2015, 09:41:26 pmNotice, that is the only one that they showed the DATEL too.

author: Octane
author_rank: Regular Contributor
timestamp: February 22, 2018, 04:25:26 am
content: 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

author: feedback.loop
author_rank: Frequent Contributor
timestamp: February 22, 2018, 05:48:06 am
content: Quote from: Octane on February 22, 2018, 04:25:26 amWhat 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

author: Octane
author_rank: Regular Contributor
timestamp: February 22, 2018, 01:38:20 pm
content: 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