Good Things Come to Those Who Wait: Like a Tektronix 2465A - Page 1
Forum section: electronics / testgear

author: Cigarsnob
author_rank: Regular Contributor
timestamp: July 10, 2013, 08:20:09 am
content: Holy smokes! I didn't think I would have been the highest bidder for a non-tested Tektronix 2465A scope, but I guess I was at $142. The scope arrived today and after thinking the worse, I powered the sucker on and to my surprise, she worked flawlessly.I'm used to working with the Rigol scope, but I think I will be making this scope my default scope from now on. I have the service/operating manual that I will definitely be reading as I need to get familiar with this one.

author: BravoV
author_rank: Super Contributor
timestamp: July 10, 2013, 09:13:53 am
content: Congratulation , now homework waiting to fresh up this gem, though its for 2465B, it should be applicable to your 2565A ->Tektronix 2465B Oscilloscope Restoration Repair (PDF), not mentioned in that document is to replace the electrolyte caps in A5 logic board that known to leak and also its very crucial to replace the battery backup ram that holds the calibration data asap.

author: w2aew
author_rank: Super Contributor
timestamp: July 10, 2013, 01:40:44 pm
content: Congratulations! The 2465 series was one of the best benchtop portable analog scopes you could buy, back in the day. Great scope. You'll see mine featured in many of my videos, along with it's special brother, the 2467. Enjoy!

author: Cigarsnob
author_rank: Regular Contributor
timestamp: July 10, 2013, 06:09:32 pm
content: Quote from: w2aew on July 10, 2013, 01:40:44 pmYou're the reason why I got the thing. I came across your youtube channel recently and instantly drooled over your scope. Love the videos...I'm a grad student and I'm always looking for more hands on experience, which is why I'm currently in the process of building some of the boards you discussed in your videos just for the experience and to keep off the mean streets of the Silicon Valley hahahaha. Thank you.Feel free to use the 2465A some more in your videos and discuss some of its features as I'm still trying to figure some of the features out.

author: c4757p
author_rank: Super Contributor
timestamp: July 10, 2013, 06:14:39 pm
content: Quote from: Cigarsnob on July 10, 2013, 06:09:32 pmI still occasionally discover a new feature or way to combine features on my 2445A, or at least rediscover something I forgot! That's not even counting (heh) the additional counter/timer module option, which IIRC is standard on the '65A - all I've ever done with that is frequency display, and I'm pretty sure it's loads more versatile.

author: Cigarsnob
author_rank: Regular Contributor
timestamp: July 10, 2013, 06:22:48 pm
content: Quote from: BravoV on July 10, 2013, 09:13:53 amThank you for the link to the restoration project. I'll give this a read soon and I'll follow your advice on replacing the electrolyte caps and the battery.I'm also trying to restore an HP 1740A that I got a month ago. Here's my link on that:https://www.eevblog.com/forum/testgear/hp-1740a-repair/

author: grenert
author_rank: Frequent Contributor
timestamp: July 10, 2013, 06:54:51 pm
content: Quote from: BravoV on July 10, 2013, 09:13:53 amDoesn't replacing the backup RAM chip wipe out the calibration data anyway? If so, may as well wait till it dies to replace.

author: dfmischler
author_rank: Frequent Contributor
timestamp: July 10, 2013, 07:17:10 pm
content: Quote from: grenert on July 10, 2013, 06:54:51 pmNot if you copy the data from it and load it into the new one. Seriously, lithium batteries are not expected to last as long as that one already has (unless it's already been replaced, but I doubt it).

author: grenert
author_rank: Frequent Contributor
timestamp: July 10, 2013, 07:35:42 pm
content: Quote from: dfmischler on July 10, 2013, 07:17:10 pmAnyone here have the capability to do that, or can share how to do this without special equipment?

author: w2aew
author_rank: Super Contributor
timestamp: July 10, 2013, 07:50:12 pm
content: Quote from: grenert on July 10, 2013, 07:35:42 pmIf you look at the schematic for that board, you can feed in a DC voltage via a diode on the board using an isolated power supply to keep the RAM contents intact while you replace the battery.

author: grenert
author_rank: Frequent Contributor
timestamp: July 10, 2013, 09:19:09 pm
content: Quote from: w2aew on July 10, 2013, 07:50:12 pmSince some models (including mine) do not actually have a separate battery (battery is embedded in the RAM), could a 5V backup battery be "permanently" added using a couple of 3V lithium cells, a voltage divider and a diode?

author: BravoV
author_rank: Super Contributor
timestamp: July 11, 2013, 06:12:24 am
content: Quote from: grenert on July 10, 2013, 09:19:09 pmAssuming its using the same as 2465B, then the cal data is stored in the battery backed up SRAM Dallas DS1225Y, then no, the lithium battery is potted tightly with epoxy with the sram chip in there, and there is no external connection for the power source.The only safe way is to desolder the DS1225Y chip, copy the calibration data, buy a fresh one, copy back the cal data and put it back on board. Digikey has fresh DS1225AD (DS1225Yreplacement), just bought few months ago with batch code dated 2012.Fyi, the cheap MiniPro TL866 Universal Programmer as reviewed by Dave officially supports this chip, mine reads and programs this chip flawlessly.Pic of my A5 board, the BBSram is the black rectangle box labelled Dallas DS1225Y.

author: EEVblog
author_rank: Unknown
timestamp: July 11, 2013, 06:19:11 am
content: Wow, score!Impossible to get in oz at anywhere near that price.

author: Bryan
author_rank: Frequent Contributor
timestamp: July 11, 2013, 07:12:27 am
content: Quote from: BravoV on July 10, 2013, 09:13:53 amI have a 2465A as well, and I found that the logic board is different than the "B" so you should be ok without having to replace the prone to leaking SMD caps on the logic board, Mine has all through hole components, no smd. Although I think I would recap the power supply and the A1 board. What is the speed of the DS1225Y, the digikey replacements are rated anywhere from 85ns to200ns. Not sure if it makes a difference.

author: BravoV
author_rank: Super Contributor
timestamp: July 11, 2013, 07:29:41 am
content: Quote from: Bryan on July 11, 2013, 07:12:27 amThe one I bought from Digikey is DS1225AD-200IND with speed 200ns works fine, anyway, the old part DS1225Y is rated at 200ns too.At the popular TekScopes yahoo group, this DS1225AD-200IND is used most of the times for the replacement, and recommended by lots of Tek experts there.

author: Cigarsnob
author_rank: Regular Contributor
timestamp: July 11, 2013, 09:12:28 pm
content: Quote from: BravoV on July 11, 2013, 07:29:41 amI have yet to open it up as I've been busy, but this weekend, I'll spend some time on it and check the caps and start making a list of caps to order and what not.To perform the DS1225Y replacement, Do I just follow what BravoV said and purchase the MiniPro TL866 Universal Programmer to get the data off the chip and then program the new one? I've never done this before, so I would rather get the proper instructions before mucking with it.

author: endzone
author_rank: Newbie
timestamp: August 21, 2013, 06:04:21 pm
content: they sell them on Maxim (Dallas ower) site.direct and have the newest batteries. (current date code is 1333) ww 33and their NVRAM FAQ page answers that and all other possible questions.after over 25years the ram is faster (Moores law) die shrinks and now are lightning fast. buy the fasted cheapest speed. faster than yours,example: if 25 years ago it was dash 120, buy dash 70 because they have highest yeild for that speed, see the prices, the most fast will be more expensive, just like your microprocessor.the memories are HAND selected. for lower than 1uA stand by current. to assure 10 year + life.it is the best of the best,they also don't leak , from battery failure (the dangling battery ploy?). saving a $5000 instrument.