Perhaps if you share EEPROM P/N we can understand why KS cannot replace or update it?
On May 2, 2018 5:37:23 PM GMT+08:00, "David C. Partridge" <[email protected]> wrote: >My bet is that they've lost the "secret sauce" for updating the EEPROM >:( So it's measuring as best it can with no calibration adjustments >stored. > >Dave >-----Original Message----- >From: volt-nuts [mailto:[email protected]] On Behalf Of Dr. >David Kirkby >Sent: 02 May 2018 00:47 >To: [email protected]; Discussion of precise voltage >measurement; [email protected] >Subject: [volt-nuts] Two 4338B high resistance meters fail on the same >range - Keysight can't adjust EEPROM of either. > >I"m pulling my hair out over an identical problem on two instruments. I >am >hoping someone might think of a possible cause I have not thought of. >Sorry >the post is a bit long, but this is not any easy problem to describe. > >I have an Agilent 4339B high resistance meter. This instrument >essentially >consists of a variable power supply (0.1 V to 1000 V) and a very >sensitive >ammeter. It works out resistance using Ohms Law. It can display >resistance, >current, surface resistively and volume resistively. > >The service manual states there are no adjustable components in this - >all >calibration is performed using software that updates an EEPROM. The >EEPROM >is on the CPU board. > >This was sent to Keysight in the UK for a firmware upgrade and >calibration. >They updated the firmware (stored in a ROM), but the 4339B failed >calibration. > >* All the output voltages from the internal PSU were within >specification. > >* The 10nA current range was slightly out of specification. It was >reading >about 0.8℅ high, but the specification is about +/- 0.6%, so it was >only >slightly out of specification. (All other ranges were within >specification, >but some were not far from the limits. One range might have been 0.5% >off) > >I think the full scale of the current ranges are 10 pA to 100 uA, so 10 >nA >is not at either extreme. > >* All resistance measurements were within specification. (Keysight test >up >to 1e11 ohms, but it can read up to 1.6e16 ohms. I guess they simply >can't get accurate resistors above 1e11 ohms). > >Calibration at Keysight includes any firmware upgrades if you request >updates. It also includes the cost of any adjustments needed - unlike >most >calibration labs. > >Keysight said the EEPROM could not be adjusted to bring the 10 nA range >within specification, so it needed a new CPU board. I never received a >formal quote for repair, but I was told about £2000 (GBP), which seemed >a >lot considering the CPU board is about $600 (USD) from Keysight. > >These meters sell for around $3000, but other instruments available for >far >less use the same CPU. I was intending repairing my 4339B by swapping >CPU >boards from a cheaper instrument, and using a new EEPROM, just in case >it >was the EEPROM faulty, as that goes in a socket on the CPU board. > >However, I managed to find another 4339B at a good price, so that was >purchased and plans to repair the first instrument were put on hold. > > >I asked for a quote for calibration based on it having a blank EEPROM. >I >thought this would be advantageous, as Keysight could put each range >"spot >on". I expected the cost to be a bit higher but it was not. > >Much to my surprise, the instrument worked and seemed reasonably >accurate >even with the blank EEPROM. > >I sent this second 4338B to Keysight for calibration. A couple of days >later i received an email from Keysight telling me the second >instrument >has a fault. The fault is on the 10 nA range (as the first instrument) >and >the EEPROM can't be adjusted (like the first instrument). This time it >is >reading about 0.7% low, which is not much out considering the >specification >is about +/- 0.6%. > >So I now have two 4339Bs, both being within specification on all ranges >except 10 nA, and neither being adjustable! So naturally I queried why >both >instruments appear to have the same fault. > >I then received an email from someone st Keysight who had noticed I >said >the EEPROM was blank. He asked where did I get the EEPROM from. LUCKILY >I >had bought the EEPROM directly from Keysight, despite I could have got >s >very similar one from Mouser for a tenth of the price or a supposedly >identical one for even less from China on eBay. > >I am hoping to speak to someone at Keysight tomorrow,, but does >anyone >have any ideas what could cause two instruments to be slightly out of >specification on the same range, but neither instrument will allow them >to >update the EEPROM? > >Note one instrument reads high and the other low. I can understand that >perhaps the resistors used in the current to voltage converter on the >10 nA >range might be a bit less stable than used on other ranges, but I can't >understand why Keysight can't bring the meters in spec just by updating >the >EEPROM. > > > >Dave >_______________________________________________ >volt-nuts mailing list -- [email protected] >To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >and follow the instructions there. > >_______________________________________________ >volt-nuts mailing list -- [email protected] >To unsubscribe, go to >https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts >and follow the instructions there. _______________________________________________ volt-nuts mailing list -- [email protected] To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/volt-nuts and follow the instructions there.
