On Wed, 26 Jun 2019 at 16:33, Nigel Clarke via volt-nuts < [email protected]> wrote:
> Are we still talking about the HP 34970A data acquisition unit? > Yes Nigel, > I have a service note for the 34401A DMM, ref 34401A-05A dated October > 1994, that refers to this 400K resistor and/or a 40K resistor of the same > type causing problems in some 34401As by ageing out of spec, but although > the 34970A internal DMM is based on the 34401A I do not recall having seen > a similar service note for the 34970A. > There are quite a number of service notes for the 34970A here https://servicenotes.literature.keysight.com/litapp/SearchSN.do?method=openExternalSNSearch&prodNum=34970A The particular one I should probably address is "10 MegOhm and 100 MegOhm ranges drift out of specification due to the Ohm's current source reference resistor. This resistor may change in value with time" http://literature.cdn.keysight.com/litweb/pdf/34970A-13.pdf It applies to these serial numbers MY41003000 / MY41014500 SG41002300 / SG41007600 I have no idea if my S/N falls into one of those ranges, and I don't have any 10 or 100 M ohm resistors of known value. I wish I had a 3458A! The best course of action is probably to replace the resistor. Mine is an old HP unit, so I suspect it was made in the USA, so its S/N it outside those ranges, but I don#t know. There's another issue that may affect you too, regarding a problem on resistance measurements on 50 Hz mains supplies. That needs a firmware upgrade. I have version 12 of the firmware if you are able to blow the PROM, but you will need a pretty decent programmer for that, as its not a common DIL chip. A version 13 PROM is available for about $45, but Keysight UK will replace the PROM free of charge if the instrument is sent for calibration. Another problem is a safety issue. I may of course have missed it, and I don't know when my 34970A was > manufactured although what might be an original hP cal sticker suggests > c2001, but I don't recall either seeing any reference the 34970A in HP > catalogues prior to c1998 so have always assumed that no 34970As would be > affected. > > > Nigel, GM8PZR > Dave -- Dr David Kirkby Ph.D C.Eng MIET Kirkby Microwave Ltd Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, CHELMSFORD, Essex, CM3 6DT, United Kingdom. Registered in England and Wales as company number 08914892 https://www.kirkbymicrowave.co.uk/ Tel 01621-680100 / +44 1621-680100 _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to http://lists.febo.com/mailman/listinfo/volt-nuts_lists.febo.com and follow the instructions there.
