2465B / 2467B:  Questions about 50k Serial Number Distinction - Page 1
Forum section: electronics / testgear

author: Electro Fan
author_rank: Super Contributor
timestamp: May 23, 2014, 02:07:26 am
content: Calling all vintage Tektronix enthusiasts and other oscilloscope circuitry and Theory of Operations experts.http://kripton2035.free.fr/Resources/Tektronix%202465B,%202467B%20Oscilloscopes%20(service)%20(1989)%20WW.pdfJust checking to see if anyone here would be up for perusing Section 3 (Theory of Operation) to see what the significance might be of the two Serial Number ranges: SN B050000 & Above as described in Section 3 starting on Page 3a-1 and SN B049999 & Below as described in Section 3 starting on Page 3-1?Presumably the lower serial number range is the older circuitry? Anyone see any significant advantages or disadvantages to one range or the other? (Performance? Reliability? Serviceability/Availability of Parts? Other?)Thanks! EF

author: mtdoc
author_rank: Super Contributor
timestamp: May 23, 2014, 02:31:14 am
content: I believe one important difference is that on scopes with SN <50000 the RAM that holds the calibration data relies on an external battery. This is unlike latter serial numbers which use a Dallas RAM with integrated battery. This makes it more difficult to replace the battery without losing calibration data.

author: Electro Fan
author_rank: Super Contributor
timestamp: May 23, 2014, 03:08:26 am
content: mtdoc, Thanks - just to confirm I understand correctly - the earlier serial number units make it easier to replace the battery without losing data (ie, in this respect the earlier serial number units would be preferred) - yes?Related question: if you lose the calibration data during a battery change will the unit 1) fail to operate or will it 2) operate but be grossly out of order or will it 3) be reasonably close on measurements (but not precise)?Thanks again, EF

author: mtdoc
author_rank: Super Contributor
timestamp: May 23, 2014, 03:21:17 am
content: Quote from: Electro Fan on May 23, 2014, 03:08:26 amThat's my understanding, yes.QuoteI believe it's # 2 - but I'm not sure. I have no personal experience with the differences except that I own a low serial number 2467 and the RAM is separate from the battery in it.Have a look atthis threadfrom the Yahoo classic tek scope group for more info on the differences ( highly recomended BTW).

author: jlmoon
author_rank: Unknown
timestamp: May 23, 2014, 05:45:38 pm
content: QuoteElectro Fan,I believe you're misunderstanding the above quotation. The later serial number 2465b/2467b (>50K) have the DS1225 NVRAM chip with the memory and battery integrated. These models are much easier to maintain the cal constants with a quick backup and replacement of one single chip. The earlier models had the ram and battery separate .I have a later model 2467b and have replaced the NVRAM as of last year just to keep the machine in top shape. Every other year I go through the scope and verify the vertical amps are within cal along with the time bases. Up until a couple of weeks ago this was considered my most versatile instrument in my lab.JLM

author: mtdoc
author_rank: Super Contributor
timestamp: May 23, 2014, 06:08:04 pm
content: Quote from: jlmoon on May 23, 2014, 05:45:38 pmI'm not sure I'm following your logic. With earlier models - it's a simple procedure to replace the battery. No need to copy contents of the NVRAM and program a new one. Of course if you wanted to back up the cal constants you could also easily do it - but I've not heard of those chips failing. Maybe it's a matter of perspective?

author: casinada
author_rank: Frequent Contributor
timestamp: May 23, 2014, 06:24:00 pm
content: 2465B/2467B A5 boards with S/N < 50K are through hole and have a separate battery to store cal information. To replace the battery you have to do a hot swap or place another battery in parallel while replacing the depleted battery. The newer revision boards have the Dallas NVRAM that is a combo Memory battery in one package also the board is SMD. To replace the NVRAM you have to desolder the chip and copy the contents with an eprom programmer.

author: w2aew
author_rank: Super Contributor
timestamp: May 23, 2014, 06:30:55 pm
content: Quote from: jlmoon on May 23, 2014, 05:45:38 pmI think the later models is only easier IF you have the ability to copy the the contents of the NVRAM to a new one. Many folks don't have that ability, and find that the older models are easier - because you can carefully hot-swap the battery without losing the contents of the NVRAM.