Author Topic: Tektronix 2465B oscilloscope teardown  (Read 460509 times)

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Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #75 on: March 12, 2014, 03:28:58 pm »
Chksum3, welcome to the forum.

About the Dallas chip DS1225, only buy from big distributor as they constantly refreshes the stock, also Ds1225Y is discontinued, and can be replaced by DS1225AD. This newer version has an unique feature that it's internal battery is disconnected internally until you used it for the 1st time.

Suggesting not to buy those Ds1225 chip from surplus shop as they are mostly very old, and who knows how is the battery freshness inside, and it does not have the new battery disconnected until 1st use feature as newer AD/AB version. Just watch the date code the one that linux-works has, its still very fresh.

Regarding the tl866, lots of info here -> https://www.eevblog.com/forum/blog/eevblog-411-minipro-tl866-universal-programmer-review/

Hope this helps.
« Last Edit: March 12, 2014, 03:45:05 pm by BravoV »
 

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #76 on: March 12, 2014, 03:51:43 pm »
Thanks to linux-works and BravoV for all the info!  I just placed an order for the DS1225 from DigiKey. They did have the DS1225Y-200 in stock! (part#: DS1225Y-200+-ND; IC NVSRAM 64KBIT 200NS 28EDIP). Price: $23.13.  I was about to return the programmer (GQ-4X) that failed to write to the jamco chips; I'll hold off for a few days as the problem may not have been with the programmer. Again, many thanks for helping me out of the NVSRAM ditch.  -- Gary
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #77 on: March 12, 2014, 04:00:55 pm »
jameco is usually ok.  they are not a surplus shop, they are like a mouser, but just smaller and not as common or as cheap to order from.  they go way back to the 70's when they were 'james electronics', so they are not new to the business.  but on this part, they may have old stock and for battery based things, that's not good.

 

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #78 on: March 14, 2014, 11:46:20 pm »
I'm happy to report that I just received a new DS1225Y-200+ NVSRAM from digikey, plugged it into the GQ-4X USB Universal Programmer (under Windows Vista), and got a clean write and subsequent read of linux-works' 2465B calibration .bin file image. This verifies that two DS1225Y-200 chips purchased from Jameco were not functional, and that my GQ-RX programmer works just fine.  The next step is to take my nicely functioning 2465B, de-solder the aging DS1225Y, take that image, write it to the new chip, and install it - via socket - into the scope.  Thank you again to linux-works and BravoV for all your help! 

PS - In word of explanation: I decided to first buy the "Y" version rather than the "AD" version of the DS1225 given the initially frustrating attempts to write to the Jameco chips.  I understand the "AD" chip would have a freshness guarantee, so to speak, given its first turn on would be at first write, but ... I decided to limit variables and take small steps by installing an exact replacement type.  Now, once the .bin image is safely tucked away and the new "Y" is in, the process can be easily repeated with an "AD" version years down the line.
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #79 on: March 15, 2014, 12:06:55 am »
interesting how the jameco chip just would not work.  what was the date code on that one?

glad you got it sorted out.  sounds like you are on your way.
 

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #80 on: March 15, 2014, 01:08:01 am »
I'm not sure how to read the date code.  Here are the numbers associated with the two non-functioning Jameco chips:

NON-PIN SIDE --> Both chips: 1207C 386017
PIN SIDE         --> Both chips: DS1218  1102D1

Here are the numbers associated with the one functioning Digikey chip:

NON-PIN SIDE --> 1334D5 391308
PIN SIDE         --> DS1218  1314D1 113AT 

Are there dates coded here?
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #81 on: March 15, 2014, 02:21:43 am »
I'm pretty sure the 1207 is a date code (year 2012, not very old at all).

ds1218 though?  should be ds1225, no??

1334 is also a date code, and that would be 2013, very fresh chip.
 

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #82 on: March 15, 2014, 03:32:06 am »
I did a little Googling and found that a DS1218 is the CMOS circuit within the DS1225 that monitors power input to it (or not) and switches the battery on when appropriate to provide power to the SRAM module - converting it to a nonvolatile package.  That is, nonvolatile until the battery eventually dies.
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #83 on: March 15, 2014, 03:34:16 am »
ah!  now I know what you are referring to.  'pin side' meaning BELLY side of the chip (lol).  yes, I see that on mine, too.  the 8pin dip embedded (potted) inside the chip.

ignore that.  that chip is not the one you care about.  the whole module date (the top of the module, pins facing away from you) is the date code you care about.
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #84 on: March 15, 2014, 04:18:26 am »
Gary, good to hear you've solved the problem. The Digikey's one looks very fresh, date code 1334, thats 2013 week 34, manufactured about last Aug 2013. This chip even in use will last > 10 years. Mine pulled from the 2465B with date code manufactured in 1989 (25 years  :o) is still working fine when I tested few months ago. 

Meanwhile the two from Jameco are not that old either, made around Feb 2012 (date code : 1207), curious why they're broken ? Assuming these are never used chips.

How much these Jameco DS1225 cost you ? If its too cheap, afraid they're knock off/fake ones like those sold at Aliexpress, some are even selling them at $2 with free shipping.

Btw, since you're using linux-works's SRAM image now, which carries unique calibration settings, have you measure it with some references to see if the cal is out way too much ?
« Last Edit: March 15, 2014, 04:21:28 am by BravoV »
 

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #85 on: March 15, 2014, 06:04:04 am »
Thank you, but I've solved only the reading / writing to a new DS1225 to date.  I used linux-works' SRAM image as a test of the functionality of the new DS1225 and universal programmer -- I was able to get the image in and read it back out.  I haven't yet opened the 2465B, so I haven't yet gotten my hands on the SRAM image contained in my scope.  Once I gather a few more details, I'll dive in, hopefully be able to extract the chip without damaging traces, etc.  Only then will I read the data, program the new DS1225 and reinsert it via a socket.  In other words, there is a long way yet to go. 

Part of my preparation has been to review your terrific tear-down documentation from Nov. 2011.  My plan is to investigate any potential road-blocks in removing the A5 board, then determine whether my solder - desolder station will be sufficient to the task, and if so, what temperature settings and what kind of solder should be used in seating the new socket.  In other words, I plan to go slowly and try not to screw anything up! I've fixed a few things in the past (my ICOM R7000 receiver for example), but the complexity of the 2465B is another level altogether. <gulp>  Oh... you asked about the Jameco chip price -- they were ~$11.00.
« Last Edit: March 15, 2014, 06:05:40 am by chksum3 »
 

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #86 on: March 15, 2014, 04:57:40 pm »
Well, I awoke and just couldn't hold back any longer.  The 2465B was opened and the DS1225Y chip was desoldered, read, re-read, inspected, and photographed. Its date-stamp is 9404D3, which I believe is April 1994 (?). The new DS1225Y was then written to and verified, then inserted into the scope.  Everything was reattached, screwed down, re-cased, and plugged in.  The switch was thrown and behold - the 2465B started up normally and functions perfectly.  Hurray! Again thank you for providing such clear instructions out here!  I'll work on uploading the calibration .bin file.
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #87 on: March 15, 2014, 05:06:26 pm »
Congratulation, well done.  :-+

Btw, if its not troubling you too much, please the photo of your A5 digital board, and also the zipped file of your SRAM image if you don't mind, and attach it here in this thread as another Tek 2465B references.

Hopefully it will be useful someday for other 2465B owners.


Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #88 on: March 15, 2014, 05:28:13 pm »
Thanks. OK, I've attached an image of the reinstalled A5 board and a zipped copy of the .bin file now safely written to the new DS1225Y-200.
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #89 on: March 15, 2014, 05:34:59 pm »
if you did not change out those 4 smd lytic caps, you will want to.  those are on the 'must change out' list.
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #90 on: March 15, 2014, 05:36:12 pm »
Thanks !  :-+

Wow, I noticed there are 3 dark spots that look like scorched badly, the damages caused by the leaked caps is really nasty.  ???

Btw, your firmware there at the EPROM labeled 160-5877-02, any chance you can read and post here too ? Really curious as mine (see the 1st post) is 160-5877-01.

My TL866 reader/writer just can not handle this rom type which is D27011.  :-//

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #91 on: March 15, 2014, 05:49:02 pm »
I bought this scope on EBay from - rcatechalert_guy - as having been refurbished as follows: "The LV power supply filters (Capacitors) replaced with units with better specifications; The A5 control board SMD capacitors were replaced and potted.  Do you see evidence that this was not done?
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #92 on: March 15, 2014, 05:51:26 pm »
I agree, there are LOTS of black areas there!  what the heck is going on??  some exploded parts?

looks like someone also touched some of the red wima caps with a soldering iron? ;)

if you can get some close-ups of the dark areas of that board, that would be useful. 
 

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #93 on: March 15, 2014, 05:52:37 pm »
The areas that look like scorch marks are actually a resin of some sort. I'm assuming that this was done to protect against any future capacitor leakage damage, but I can't see through the stuff.
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #94 on: March 15, 2014, 05:53:08 pm »
I bought this scope on EBay from - rcatechalert_guy - as having been refurbished as follows: "The LV power supply filters (Capacitors) replaced with units with better specifications; The A5 control board SMD capacitors were replaced and potted.  Do you see evidence that this was not done?

please do get us some closer photos.  if you want, I could help take some photos (if you are bay-area based).

I was very close to buying from that very person and I read his write-ups on ebay.  if that is 'potting', then I'm a monkey's uncle....

nothing should be 'potted'.  this is an SMD board and there are proper smd parts that should fit there.

I hope he did not butcher your board!

and if he did service on this board, why on earth did he not replace the dallas module?

this does not look good, I have to say ;(

 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #95 on: March 15, 2014, 05:54:38 pm »
The areas that look like scorch marks are actually a resin of some sort. I'm assuming that this was done to protect against any future capacitor leakage damage, but I can't see through the stuff.

that's not a typical repair procedure that I'm aware of.  you replace the bad caps, you clean the board and solder new ones there.  I used polymer caps so there can't ever be leaking again.  I can give you the part #'s from mouser if you want.

having work done on a board like that would make me quite uneasy about what else was done, and HOW well it was done.  yikes!

 

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #96 on: March 15, 2014, 06:04:30 pm »
Here's a closeup of the resin covered areas.  Yes, I was disappointed to see the work up close and personal. On the other hand, the scope appears to be functioning well and, as they say, the deal is done.  With all the resin (?) now present, my first reaction is to leave it alone and not try removing it. If the scope at sometime fails, I'll of course be forced into action. 
 

Offline linux-works

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Re: Tektronix 2465B oscilloscope teardown
« Reply #97 on: March 15, 2014, 06:09:01 pm »
I would also be concerned with any of that resin affecting the circuitry.  on high frequency layouts, capacitance and trace leakage can be an actual issue.  I don't know the a5 board well and maybe those things don't matter here (its not an analog input section or high z section) but it just looks real bad to me.

if I saw that in my scope, I'd return it and give the seller a super strong negative for being incompetant and claiming otherwise.  wow.  just wow.  maybe I'm over-reacting but I do not like the look of that one bit!

if it works, that's fine.  but it sure looks like a teenager hacked your scope and not a professional.
 

Online BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #98 on: March 15, 2014, 06:14:16 pm »
Geezz Gary, I just downloaded your A5 board photo, and starred it for a while, must be really bad there. I slightly enhanced yours to show the dark spots, and compare with mine at the left side.

See the arrows I put there ? Also I'm very concern of the high precision 10 Mhz oscillator (blue box at the bottom), it seems like its so dark that I can't recognize it anymore.  :-//

Attached below the quite big sized picture I just made, suggesting to right click the thumb pic and view at other window for best resolution.

Offline chksum3

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Re: Tektronix 2465B oscilloscope teardown
« Reply #99 on: March 15, 2014, 06:29:01 pm »
Yep, the resin coating is ugly and inexplicable - I don't understand the need to have done this, unless there was leakage and damage then wire used in place of traces to reconnect the damage pathways, then resin to cover the whole thing.  Definitely a messy job at best. Why the 10Mhz oscillator is resin covered is another mystery.  Ugly, ugly, but appears to be functional.  I've decided to write the seller and ask what this is about.

Regarding the D27011 EPROM: my programmer also does not include that one on the list of supported chips.
 


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