Keithley 196 EPROM and EEPROM backup equivalents - Page 1
Forum section: electronics / testgear

author: don.r
author_rank: Frequent Contributor
timestamp: September 06, 2017, 02:31:46 am
content: I'm going to back up the firmware and calibration for my Keithley 196. The firmware EPROM is a 27128 and seems readily available new. The calibration EEPROM is a KM2816A-30 (300ns?) and seems to be difficult to find new. Is there an available cross reference for this EEPROM? Can I use a faster one (some NOS 250ns ones appear to be kicking around)?

author: don.r
author_rank: Frequent Contributor
timestamp: September 07, 2017, 11:45:05 pm
content: I have backed up and have a copy of the 196 800/801 B15 firmware in case anyone needs it.

author: bitseeker
author_rank: Super Contributor
timestamp: September 08, 2017, 12:10:49 am
content: I haven't gone inside my 196, but will follow along as I may have to deal with that at some point, too.

author: Ash
author_rank: Regular Contributor
timestamp: September 08, 2017, 01:29:04 am
content: Hi,Same situation here...I have B16 and B17 code, plus images of the associated calibration data. However I don't trust the cal data as the units came to me requiring repair.I'm still working on one (it seems to have suffered an over voltage/current event) and I believe that someone has tried to re-cal it before me.. I've had to replace many of the analog switches and the entire MOSFET stack that switches (I believe) current ranges. It is now kind of working, but the low 3 digits are noise still so there are other faults awaiting discovery (and time to look at them)..Ash.

author: don.r
author_rank: Frequent Contributor
timestamp: September 23, 2017, 08:06:13 pm
content: First attempt with the EPROM was a bust. The ones I received were duds. One tripped the overcurrent protection in the programmer and the other refused to program after about 50 bytes. I'll have to get some from a more reputable source.

author: bson
author_rank: Unknown
timestamp: September 23, 2017, 11:23:45 pm
content: Can't you use any 2716 pin compatible EEPROM from e.g. Winbond?Edit: oh wait, the device needs to be able program it by itself on calibration.

author: don.r
author_rank: Frequent Contributor
timestamp: November 11, 2017, 10:03:47 pm
content: Everything is now programmed. Just need an opportunity to tear down the 196 and try them out.

author: don.r
author_rank: Frequent Contributor
timestamp: February 03, 2018, 07:20:07 pm
content: OK. EEPROM and EPROMs have been installed and work fine.EPROMs are from ebay seller horizon_electronic and are listed here in 5 packhttps://www.ebay.ca/itm/5PCS-M27C128A-10F1-IC-EPROM-UV-128KBIT-100NS-28CDIP-NEW/281986504934?hash=item41a7b498e6:g:BykAAOSwzvlW~JFQEEPROM is from ebay seller crystal830303 and are listed in 10 pack herehttps://www.ebay.ca/itm/10PCS-XLS2816AP-250-Encapsulation-DIP-24-EEPROM/272358161552?hash=item3f69cfbc90:g:lH8AAOSw~oFZ1fbh250ns parts work just fine, as expected.I have 9 of the EPROMs left and am willing to sell a few so PM me for that.Having looked around the boards, I noticed one of my caps beginning to look a little funky. Can anyone confirm that theirs is the same? Its the green Richey cap next to the small heat sinks. Looks like the vents are starting to bulge.

author: bitseeker
author_rank: Super Contributor
timestamp: February 04, 2018, 01:48:04 am
content: That cap looks OK from the photo. Do you see a lot of ripple from the power supply?I opened my 196, but it looks like it requires quite a teardown to get to those caps.

author: don.r
author_rank: Frequent Contributor
timestamp: February 04, 2018, 03:27:36 am
content: I haven't tested it for ripple yet. I've misplaced my esr meter (my son probably has it) but once I find it I'll check it in circuit.Its not too bad to get into. Remove two screws and remove top shield. Unplug front and rear connectors from pcb by pulling pins straight up (colors are marked on pcb). Remove main connector at front of pcb. Remove analog board. Remove 4 screws and lift off second shield and your done.