Tek TDS3000 series and Dallas NVRAM - Page 1
Forum section: electronics / testgear

author: MarkL
author_rank: Unknown
timestamp: September 25, 2014, 04:10:03 pm
content: I was performing a minor repair on a TDS3054 (not B or C version), and I noticed a "Dallas DS1742W-150 Timekeeping RAM" soldered onto the main board. The date code is 1999, and the Dallas datasheet claims a minimum of 10 year life expectancy for the battery.Does anyone know if the cal data or other critical information is stored there? Is there any known backup procedure besides unsoldering it and reading it out on a programmer? Perhaps via the GPIB?Has anyone seen any TDS3000 NVRAM go bad?Given the actual lifetime reported on other Dallas NVRAM parts in other scopes, I probably still have many years left before I have to deal with it, assuming I keep the scope that long.And a side note... The repair was to replace the CCFL tubes on the display which was getting very dim. There are two CCFL tubes and they slide out as modules. It's a trivial repair, although getting to the display itself requires a bit of disassembly. Display is part #NEC NL6448AC20–06, CCFL modules are 65LHS–3L. You can also get bare CCFL tubes (2.6mm x 153mm) and solder them in the modules yourself for much less. FYI.

author: voltsandjolts
author_rank: Unknown
timestamp: September 26, 2014, 09:18:20 pm
content: I replaced the NVRAM in my TDS3034 as a precaution - I didn't know if there was any critical info in there.Turns out there isn't, so its safe to let the NVRAM battery die before replacing it.The only difference I could see by fitting a new blank NVRAM was the "number of powerups" in scope diagnostics was reset to zero.I think the NVRAM just stores scope setups, timebase, volts per division etc.Thanks for the display and CCFL PNs, hopefully I won't need them!

author: David Hess
author_rank: Super Contributor
timestamp: September 26, 2014, 10:19:18 pm
content: Wow, that is good to know.Earlier Tektronix oscilloscopes stored the calibration data in the NVRAM leading to a difficult or costly problem if the contents were lost.

author: HighVoltage
author_rank: Super Contributor
timestamp: September 26, 2014, 10:25:19 pm
content: Quote from: voltsandjolts on September 26, 2014, 09:18:20 pmI also have an older TDS3034 and may be I should replace the NVRAM.Did you replace it with the same "Dallas DS1742W-150 Timekeeping RAM" or are there alternatives?Thanks for this great information.

author: David Hess
author_rank: Super Contributor
timestamp: September 26, 2014, 10:56:45 pm
content: Quote from: HighVoltage on September 26, 2014, 10:25:19 pmYou can use a faster one to replace a slower one. I see plenty available at Mouser and Digi-Key although they cost more than $20 each.I am not aware of any third party equivalent replacements. I know this issue has come up for older Dallas Timekeeping RAMs which they no longer produce. In those cases, the Timekeeping RAMs were replaced with standard NVRAMs and the oscilloscope still worked but without the time and date functions.

author: MarkL
author_rank: Unknown
timestamp: September 27, 2014, 01:57:42 am
content: Thanks for the info on the NVRAM, voltsandjolts!It's good to know design mistakes of the past don't always repeat themselves.

author: voltsandjolts
author_rank: Unknown
timestamp: September 27, 2014, 08:40:30 am
content: @HighVoltage"Did you replace it with the same "Dallas DS1742W-150 Timekeeping RAM" or are there alternatives?"Yes, I used that Dallas part. Not cheap.

author: prot_brot
author_rank: Contributor
timestamp: February 10, 2015, 04:10:46 pm
content: Will DS1642 work? it has the same 2k x 8 ram and pinout as the DS1742 at half the price

author: Jwalling
author_rank: Unknown
timestamp: August 09, 2016, 05:06:35 pm
content: Quote from: MarkL on September 25, 2014, 04:10:03 pmHad an opportunity to read out the contents of the Dallas chip in a TDS3014BIs it possible that there is a back-door into these? I'm no hacker, completely clueless even.I've attached the binary as well.EDIT: Typo. Always a friggin' typo!Jay

author: CNsam
author_rank: Contributor
timestamp: November 23, 2023, 10:11:36 am
content: Copyright 1984-1996 Wind River Systems, Inc.CPU: Tektronix HPP - PowerPC 740Version: 5.3.1BSP version: 1.0.3.0Creation date: Jun 28 2000, 16:52:12Press any key to stop auto-boot...0auto-booting...There's no way I can make it stop! what should I do!

author: duster
author_rank: Newbie
timestamp: April 17, 2025, 11:15:22 am
content: Thanks your share，it works on my TDS3012B scope，Thanks a lot!