Keithley 2700 component identification - Page 1
Forum section: electronics / repair

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: August 25, 2019, 04:03:07 am
content: Hello, I've got a Keithley 2700 multimeter from usual place with some problems. This is the first one of those I've ever looked at. It doesn't take any meaningful measurements on any range.... tough spot.I wanted to first deal with obvious. When I've opened the meter I've found two components that are definitely burned out.There is a resistor and I guess capacitor that are smoked.I'm attaching some pictures for your entertainment.Maybe somebody out there has idea what I can replace it with.....I've tried to run the test... like Kei2000 but it looks like I can't find the option to run the test... not sure what's wrong with it but I'm getting calibration (the calibration count, dates, run... display test and key test.... am I looking in a right spot....I'm getting a 520 error at the start but it looks like it's related to the setting on the acquisition card, still don't know how to resolve it. I've tried to restore default setting but again.. it doesn't like like it's the same as Kei2000...

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: August 25, 2019, 04:14:59 am
content: It looks like when I short the burned out resistor with my trusty tweezers the resistance measurements are right on the money... almost.So, this is the first measurement I can actually see that's in any way meaningful.

author: fzabkar
author_rank: Super Contributor
timestamp: August 25, 2019, 05:56:18 am
content: Here is a service manual:https://elektrotanya.com/keithley_2700_sm.pdf/download.html#dlR196 is a 2K, 1%, 125mW, metal film resistor.R298 is a 1K, 1%, 100mW, thick film resistor.I would think that the adjacent semis would be suspect.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: August 25, 2019, 03:57:56 pm
content: Thank you. I’ve got rid of an error 520, meter uses saved configuration “save0”, I’ve had to save the new configuration and the error went away.

author: Ordinaryman1971
author_rank: Frequent Contributor
timestamp: September 04, 2019, 03:30:54 am
content: I found two transistors that are blown the Q114 and Q136 the marking on them says (132), in the manual it says... TG389, I wonder where can I find those.Another one that I need is CR116 dual diode, marking on it is (C2Y) RF-95, HSM-2822T31.And of course the resistors... R298 1K and R196 2K.

author: fzabkar
author_rank: Super Contributor
timestamp: September 04, 2019, 04:45:47 am
content: Could the C2Y be a HSMS2822? This dual Schottky diode has a marking of C2x, where x is the date code.http://www.redrok.com/Diode_Schottky_HSMS-282x_1pF_100pS_12O_0.34V_-15V_AVAGO.pdfEdit:Page 109 of the PDF states that CR116 is a BAV99L dual switching diode.https://www.onsemi.com/pub/Collateral/BAV99LT1-D.PDFQ114 and Q136 are n-channel JFETs, SNJ132199.The same transistors appear on page 6 of the following circuit diagram:https://xdevs.com/doc/Keithley/2000/K2000.pdfEdit #2:http://dedius.free.fr/index.php?post/2014/11/06/Keithley-2000-repairQuotehttp://dedius.free.fr/public/Bricolage/KEITHLEY/nj132_interfet_process.pdfhttp://bardagjy.com/?p=1167QuoteMMBF4391L, MMBF4392L, MMBF4393L JFET Switching Transistors, N−Channel:https://www.onsemi.com/pub/Collateral/MMBF4391LT1-D.PDF