Author Topic: Tektronix 2465B oscilloscope teardown  (Read 380268 times)

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Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #700 on: March 24, 2016, 03:08:36 pm »
Ok - As written above, was successful in removing the original DS1225Y from my 2465B scope and retrieving the cal data using a GQ-4X4 programmer.   Then the data was successfully written onto an FM16W08 which has been working great in the scope for the last several weeks.

The last problem was getting the same data to write to a spare FM16W08.   It's symptoms were that the D1 data line would only write a "1."   Contacted GQ Support for suggestions (they supplied the custom software for me that includes the FM device).   They made some general suggestions that we had mostly tried, and said they would order an FM IC and troubleshoot the software problem at their location.   So I ordered 2 more FM IC's as a shot in the dark from my end.

My replacement IC's came in yesterday.   Soldered an FM IC to the new adapter board, inserted it into the GQ Programmer - and it work perfectly!

We re-tested the failed FM IC and the problem with the D1 data line was the same.   Taking a closer look at the physical pins with an eye loop, magnifiers and bright lights from various directions revealed that pin 12 (D1 data line) had less solder than all the other pins, but otherwise looked ok.   As another shot in the dark, I re-soldered pin 12, inserted it into the programmer - and it worked perfectly!   Whewww!

Then we turned to the new DS1225AD I had previously purchased for a parallel effort with the FM16W08.   Problem was, it too had failed to write/load correctly.   As before, it loads all the data correctly except for the first byte which displays "FF" (hexadecimal code).   Again we tried everything thinkable with no luck.   The DS IC does not need an adapter board so there are no solder issues there.

Sent this most recent information off this evening to GQ Support including the issue with the DS IC.   So, the present status of my coveted scope cal data is - - -  One new FM IC installed in the scope.   Two spare FM IC's on adapter boards correctly programmed and stored.   The cal data is stored on my XP computer.   The cal data is stored in 4 places in my Windows 8.1 computer.   A copy is on a memory stick.   And I have a hard copy of it stored in the scope binder.   And, not to mention the DS1225AD that may get working.   And, the original DS1225Y that was removed from the scope is still alive and showing good battery voltage.   Oh yeah - someone else here suggested that one needs another memory stick duck taped to the inside of the scope housing.   This way, when the EMP strikes, at least one memory of the data should survive - but of course the scope won't :palm:

Nothing paranoid here about saving cal data.   Its just that it takes so much effort to retrieve and save, that no one wants to risk loosing it.
 

Offline ChunkyPastaSauce

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Re: Tektronix 2465B oscilloscope teardown
« Reply #701 on: March 24, 2016, 04:07:42 pm »
I need to order those caps....

Send an e-mail to yourself if you have something like gmail, or upload to cloud.

Or upload here so if people what to look at the cal data they can and you have a backup copy.

Id put one of the FM ICs inside the case. Then if you need it, it's there.
 

Offline BravoV

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Re: Tektronix 2465B oscilloscope teardown
« Reply #702 on: March 24, 2016, 04:18:30 pm »
Old-E, really appreciate the sharing of your experiences here, thanks.  :-+


.....<snip>...

   And I have a hard copy of it stored in the scope binder.   ...


Do you mean hard copy as printed in hex at paper ?  :o

If it is, make sure you're using acid free paper that will last few hundreds of years.  >:D  ...j/k



Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #703 on: March 25, 2016, 06:56:41 am »
Good point!   Share it here and use the forum like a cloud.

Anyway, I can attach the Xcel file here of the Hex code that was manually read from my scope CRT display.   Preceding it is a page showing how to get to the scope data in order to manually copy it (not to be confused with electronically reading it from the DS1225Y once removed from the scope).

For simple minds like myself, start in the upper left corner on page 1 where it says "Press delta V & delta T + SLOPE" using the control buttons on the face of the scope.   This gets you into the Diagnostic mode which is displayed on the CRT as noted in the display column of the Excel form.   "ALL 00" is displayed at the bottom of the CRT.   Moving right the 3rd column shows that the "VERT" button is illuminated.

You may continue moving right or return to the first column and press "MODE up" button to cycle from ALL 00 to "TEST 01, which illuminates the "CH-1" button.   To test any of these routines, move to the 4th column "Action" and press "COUPLING up" button.   If that test finds no problems, it will display "TEST 01 PASS."
The chart on the 2nd half of the page is an extension of the first half, extending to the right as shown by the connecting line.

To find the cal data, toggle down to "EXER 02" and find the upper left corner of page 2.   Then follow the sequence - press "TRIG COUPLING" to display the first data point (for my scope it is "0013").   Then to continue cycling through the rest of the cal data, continue pressing "TRIG SOURCE."   The first 2 digits to the left of the cal data starting with "00" is the address location for the stored data.   This shows up in the data copied from the DS1225Y shown on the GQ Programmer display.

Following the order of the sequence laid out in the Excel spreadsheet it should be pretty straight forward and probably easier then following my verbal description here.

Note:  In theory, one could manually enter this data into a programmer and then write it to a replacement IC.   It would be time consuming and it would need to be double or triple checked to eliminate any errors, but it could be done.   I copied my data manually first because the DS1225Y was way past it's battery life expectancy, and just incase it died before it could be read electronically, at least I would have a printed copy of the cal data.  (An error in this paragraph has been corrected)

I'll write more about this later.

(The attached Excel spreadsheets have been updated with a couple of corrections, additions and an improved layout - easier to follow.  4-23-2016)
 Problem:  Page 1 of the new Excel spreadsheet wants to come up in portrait rather than landscape format.   To fix; after opening click on "Enable Editing" at the top of the page and the formatting will fix itself.   Sorry about that.   Unable to find the cause.
« Last Edit: April 24, 2016, 12:51:53 pm by Old-E »
 
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Offline ChunkyPastaSauce

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Re: Tektronix 2465B oscilloscope teardown
« Reply #704 on: March 25, 2016, 07:10:49 am »
Cool, pretty nice too
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #705 on: March 26, 2016, 07:10:12 am »
Regarding my last entry, might also mention that one could download the attached Excel file to your computer and erase just the cal data (hex code).   Then you would have a blank form to enter your own scope data on as you read it off the CRT display.

Another thought is that if you should lose your scope cal data, my understanding is that you could program your new RAM IC using this data.   Your scope then would not be precisely calibrated, but it would be close enough to get it back in operation.   Also, your recorded operating hour and power cycles would not be relevant to your scope.

Attached below is a screen print of the GQ-4X4 Programmer with my scope's cal data displayed in the buffer as if ready to be written to a FM16W08.   The FM16W08 device, indicated in the upper right, has been called up from the GQ library.   The reason I'm able to pull that IC up from the library is because I'm using the new "Hotfix" software from GQ Electronics, Support group.

FYI - Looking at the screen print shown, find the far left address column in pink.   Then find address location "00001E00."   That is where the cal data for my scope starts.   That can be seen by comparing the first series of bytes "00 13 06 BF 26 EB," etc,. - to the first data points in my Excel data sheet, page 2 (attached in my previous entry) "0013, 06BF, 26EB.   Those bytes should compare correctly all the way to the bottom of the screen print where once again we can compare the last bytes "00 27 00 00" - to the bottom of page 3 of my Excel spreadsheet where 0027, 0000 was copied from my scope's CRT display.

Obviously, above address location 00001E00 of the screen print, is a lot more recorded Hex data.   So, what is that?   It apparently it is not cal data, because it is not displayed on my scope.   I believe it is non-critical stuff, like hours of operation, scope set up sequences (where one can record the scope settings by pushing a button, and then retrieving it in the future for the same setup, and who knows what else.

Correction - In my previous entry, I wrote -  (Previous entry now corrected)
Note:  In theory, one could manually enter this data into a programmer and then write it to a replacement IC.   It would be time consuming and it would need to be double or triple checked to eliminate any errors, but it could be done.   One problem with this is that, the GQ Programmer that I used here is not sophisticated enough to manually load data - per my limited knowledge.
Facts are - A friend pointed out that the GQ Programmer can manually load data!   But if one was loading only what was copied off the scope CRT, it would be missing all the data we see in memory preceding the cal data.   And this brings me back to the question of, is the preceding data critical to operations?

Another thought that might work (per my limited knowledge), would be to load a full set of data from another scope electronically into your RAM IC.   Then go back and manually modify just the cal data part to what you had copied off the CRT display on your scope before the Dallas IC died.

I'll write more later. 
« Last Edit: March 26, 2016, 08:22:06 am by Old-E »
 

Online tautech

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Re: Tektronix 2465B oscilloscope teardown
« Reply #706 on: March 26, 2016, 07:19:43 am »

Correction - In my previous entry, I wrote -.........

I'll write more later.
Do consider Edit or Modify to a previous post so your great info reads correctly in that one post.

I't not a crime to make Edits and best if you also make a post to say that you've done so in case readers had saved your very good info.
Avid Rabid Hobbyist
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #707 on: March 26, 2016, 08:29:26 am »
Tautech - Good suggestion.   Correction above dually noted.   Thanks.
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #708 on: March 27, 2016, 06:46:56 am »
More about the GQ-4X4 Programmer.

As mentioned before, the GQ programmer does not include the Ferromagnetic IC FM16W08 in its library, that some of us have used to replace the battery powered RAM DS1225Y.   The advantage of switching to the FM16W08 is that it will not lose it's recorded data when the power is switched off - no need for battery backup.   To the external world, everything looks the same (voltages, pin outs, etc.) except for one detail.   And that is the way the data lines are toggled.   But the good news is that the scope happens to be logically configured to work with either IC.

So, following someone else's report, I bought this GQ Programmer and tried to write to an FM16W08 by using the DS1225Y listed in the Programmer's library.   And it didn't work.   Even tried down loading some older software thinking that maybe the report writer might have used it with success.   But no luck.   I contacted GQ Support for help.   They confirmed that the GQ programmer would not load an FM16W08 in place of a DS1225Y.

And further more, only their recent latest model, GQ-4X4, could even be configured to do that (GQ-4X model could not).   The way to determine if you have the 4X4 version is you will hear 2 audible beeps when you apply power to it using the USB cable to your computer.   Mine beeped twice.   Wheeew!

John in Support was very helpful and, a number of communications later, he sent a custom Hotfix program for my Programmer.   After loading it, there was the FM16W08 IC in the library.   Skipping more details, the Programmer worked great in transferring the data from the DS1225Y to the FM16W08.   John said they would be including that IC in their next updated software version.   I get the impression they release newer versions every year or so.

Getting to the bottom line here, I received confirmation from John at GQ Support a couple of days ago, that it would be ok to share the modified software with anyone that wanted it.   I had told him about my entries in this forum about the GQ Programmer, and had received a request for a copy from one of the forum people.   The latest standard software version is 7.07,   This modified version is 7.08 (3.81 meg).

Assuming this attachment process works, and you have it down loaded on your computer, I would suggest that you disconnect your computer from the internet for the duration that your Programmer is displayed/open.   Reason is; as soon as you open it, the programmer automatically goes on line looking for the latest version of software.   Version 7.08 is later than 7.07, so this should not be a problem, but I didn't want to chance getting the 7.08 version overwritten with something else.

Got a problem - This attachment will not work here.   Tried several times.   Error message says it may be too big of a file.   So plan B might be to see if it can be made available on line for readers to download from the GQ site.   In the meantime, I can send it by e-mail to any individuals that contact me at  don9@tds.net

Sorry about that!
« Last Edit: March 27, 2016, 08:09:30 am by Old-E »
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #709 on: April 02, 2016, 12:34:40 pm »
Finally - total success!!!

Received the latest version of custom software from GQ Electronics.   The degree of special help I've received from them has been amazingly positive!   My communications are almost always answered in a few hours, and almost anytime of day or night!   It's pretty incredible!

This software version 7.08B was to also add the DS1225AD to the library.   I was unable to write correctly to the AD version when using the Y version in the library.   Both chips are supposed to be the same, in that respect, so it appears there was a bug in the Y version of the software.   But, regardless, the AD version is there now and works with an AD chip.   The DS1225Y has been noted as obsolete, and superseded by the AD.   So, now I have more than an adequate number of IC's loaded with my scope's cal data.

For anyone wanting to obtain a copy of the latest version of custom software that now writes correctly to the DS1225AD and the FM16W08, I'll be happy to e-mail you a copy, because the file is too big for this Forum.   Eventually it will be included in GQ's next published upgrade.

Don
don9@tds.net

 

Offline MSO

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Re: Tektronix 2465B oscilloscope teardown
« Reply #710 on: April 02, 2016, 05:20:20 pm »
Nice work, Don.

For those who might attempt restoring their calibration data from the data read using EXER 02, the bytes are not swapped in binary image; that is if a location reads on the scope's display as 2071, it's 2071 (not 7120 as Intel does it) in the binary image as well.

I've attached both a binary copy and an ascii (human readable) copy of my NVSRAM image for those who might find it useful.  My 2467B is serial number is one of the newer ones beginning with B053xxx. I don't know if it makes any difference, but just so you know.

You can load the binary (.BIN.HEX) file directly into your programmer; the ascii (.TXT) file would have to be converted to binary before it would prove useful. Beware though, most programmers will load the text file and write it out to chip, making the chip as useful as pebble, so don't do that.  I use the text version just to browse the data and see what's in it.

 
 
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Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #711 on: April 05, 2016, 02:57:00 pm »
Bit of trivia - - 

:palm:    "Finally - total success!!!"   Opening my last message with this sounded a little too absolute at the time.   And sure enough, as soon as I notified the world, including this forum, that the last remaining obstacle in the GQ software tested good, I received this message back from GQ Support -

Hi? Don?

Thank you for your update.

It is the best to test the new software with FM16W08 .  Because there are partially over lapped.

The new version will be released once other chips been added.

Best Regards.
John

In other words, their last software mod that fixed the DS1225AD problem had elements common to the FM16W08.   So, confirming that the DS1225AD worked, did not mean that the FM16W08 still did.   This produced the Ohhh! Nooo! moment.

So, over the weekend, I pulled one of my previously programmed FM16W08's out of storage to run through a test routine.   FYI - That consisted of loading all FF's in the programmer buffer.   Then writing that over the top of the scope cal data, and reading it back to confirm that indeed all FF's were displayed.   All FF's sets all the inputs high.   Then it was repeated with all 00's to set all the inputs low.   Then repeated again with all 55's, and then all AA's, to load the IC with alternating highs and lows.   When that was successful, the scope's cal data was loaded back in the IC, and confirmed before putting it back in storage.   Wheeew!

It worked!   So now I don't have a lot of explaining to do.   Notified GQ Support and received the following reply.

Thank you very much for your testing.

Now we can claim those two chips are supported.

Cheers.

John


So, whenever GQ's next software version is released to the market place, these 2 IC's will be in it.   In the meantime, I can share it with the forum.
 

Offline Mosaic

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Re: Tektronix 2465B cal
« Reply #712 on: April 09, 2016, 02:16:20 am »
Hi all:
I justed posted this item on EBAY 131775163056
It is for the SG504 Leveled Sine wave gen - a better substitute head.

Ancel
 

Offline RF_Pursuit

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Re: Tektronix 2465B oscilloscope teardown
« Reply #713 on: April 10, 2016, 05:23:40 am »
After thanking med6753 for welcoming me and his valuable suggestions, I continue my post which I started here
https://www.eevblog.com/forum/repair/tektronix-2465b-tear-down-and-rejuvenation/

Today, I cleaned the A5 board from oil leaked from the capacitors and made a list of Tantalum capacitors to order and substitute.

I added a 1mm thick copper plate as cooling fins to extra cool the U800, not optimum, but a T-shirt less for the Summer!

And here comes the adventurous part (I'll post the images later). I dismantled the A5 board and I immediately started milling the DS12225 as I read in this article  http://www.worldphaco.com/uploads/TEKTRONIX_2465b_OSCILLOSCOPE_CALIBRATION___REPOWERING_THE_DS1225.pdf, because I once got an error message (test 05 fail 44).


Unfortunately, I reached almost 4.5mm deep until I saw three metal traces. I measured one of which (the mid one) to find it is 3.25 volts!

but I struggled to solder a wire on it and then sealed the hole and fixed the wired with resin.
I have the CR2032 but solder doesn't stick on it. I have to wait to buy a lithium battery micro size.

Fortunately, the SD1225 hasn't lost data.

Now there are two other problems, a broken SEC/DEV potentiometer which I fixed with  instant adhesive, and the bend traces of channel 1 and 2.  I assume this one has to do with aging capacitors in the power and vertical horizontal circuits???? I'm going to work on these boards after some consideration and collecting information.







« Last Edit: April 10, 2016, 05:27:24 am by RF_Pursuit »
 

Offline RF_Pursuit

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Re: Tektronix 2465B oscilloscope teardown
« Reply #714 on: April 10, 2016, 07:05:14 pm »
Can someone please tell me how to get to the information on 'Switch on off times' and 'Number of Operation Hours'? Thanks!

 

Offline rf-loop

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Re: Tektronix 2465B oscilloscope teardown
« Reply #715 on: April 11, 2016, 03:02:55 am »
Can someone please tell me how to get to the information on 'Switch on off times' and 'Number of Operation Hours'? Thanks!

RTFM!  (example: 070-6873-00_2465bSvc_Sep89.pdf )


All is explained in service manual. Also even how to change these values what ever you want. (But, seriously, because you need ask this question: Warning, DO NOT enable CAL and play with CAL routines if you do not know exactly what are you doing there! )

Without enabling CAL, just only need use front panel. You need go to EXER 06 routine. It tell this info.

Page 6-10 in service manual. There is "Diagnostic routines" explained. Also how to enter to these routines.

Or, more easy: Operator manual.
http://exodus.poly.edu/~kurt/manuals/manuals/Tektronix/TEK%202445B,%202455B,%202465B%20Operator.pdf

There Appendix A "Extended functions with diagnostic exercisers"

Manuals are for reading!
« Last Edit: April 11, 2016, 03:09:43 am by rf-loop »
If practice and theory is not equal it tells that used application of theory  is wrong or the theory itself is wrong.
It is much easier to think an apple fall to the ground than to think that the earth and the apple will begin to move toward each other and collide.
 

Offline Old-E

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Re: Tektronix 2465B oscilloscope teardown
« Reply #716 on: April 11, 2016, 05:05:59 am »
RF_P -
The total scope hours and the number of power on/off cycles can be found in the scopes memory.   To access that place in memory you can follow the procedure in the Service Manual as rf-l indicated, on page 6-10 or the actual page count is 232.

Simple way to get there is -
Hold down the delta V & delta T buttons on the front panel, , then simultaneously press "+ SLOPE."   This enters you into the diagnostic mode and you will see "ALL 00" displayed at the bottom of the CRT screen.

Then press "MODE" up, button to cycle from "ALL 00" to "TEST 01."   Continue pressing "MODE" up button to cycle down to "EXER 05."   Here, you will see that the "ADD" button is illuminated.   (Pressing the "MODE" down button reverses the order)

Then press the "COUPLING" up button.   This should display your scope's hours and power cycles across the top of the screen.

To exit - press the "COUPLING" down button.   This returns you to the DIAGNOSTIC page.

Then press "A/B TRIG" to exit the DIAGNOSTIC page, returning your scope to normal operation.

There are many more options that can be accessed in the diagnostic mode.   This is just the straight line path to your requested information.

Let us know your scope numbers.   By the look of the dirt accumulated on the fan, it would appear that it has been operated outside of a clean room environment.   This can and should all be cleaned up.   And the 4 electrolytic capacitors on the A5 board should be replaced ASAP.   It appears that the board around those caps in your photo is still in good shape.   So, count your blessings.   Too often the stuff leaking out of those caps eats up traces and other components in the near vicinity.

My scope indicates over 20,000 hours & 1,100 power cycles.
 
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Offline RF_Pursuit

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Re: Tektronix 2465B oscilloscope teardown
« Reply #717 on: April 13, 2016, 08:15:41 pm »
Can someone please tell me how to get to the information on 'Switch on off times' and 'Number of Operation Hours'? Thanks!


Also even how to change these values what ever you want. (But, seriously, because you need ask this question: Warning, DO NOT enable CAL and play with CAL routines if you do not know exactly what are you doing there! )

Without enabling CAL, just only need use front panel. You need go to EXER 06 routine. It tell this info.

Manuals are for reading!

Thanks a lot I appreciate your drawing my attention not to fiddle with CAL, you're right I could've fallen in that swamp!

I was mainly busy downloading different manuals and skimming through them. And of course looking for A3 schematics but I managed this by magnifying the A4s.
 

Offline RF_Pursuit

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Re: Tektronix 2465B oscilloscope teardown
« Reply #718 on: April 13, 2016, 08:33:24 pm »
RF_P -
The total scope hours and the number of power on/off cycles can be found in the scopes memory.   To access that place in memory you can follow the procedure in the Service Manual as rf-l indicated, on page 6-10 or the actual page count is 232.

Simple way to get there is -
Hold down the delta V & delta T buttons on the front panel, , then simultaneously press "+ SLOPE."   This enters you into the diagnostic mode and you will see "ALL 00" displayed at the bottom of the CRT screen.

Then press "MODE" up, button to cycle from "ALL 00" to "TEST 01."   Continue pressing "MODE" up button to cycle down to "EXER 05."   Here, you will see that the "ADD" button is illuminated.   (Pressing the "MODE" down button reverses the order)

Then press the "COUPLING" up button.   This should display your scope's hours and power cycles across the top of the screen.

To exit - press the "COUPLING" down button.   This returns you to the DIAGNOSTIC page.

Then press "A/B TRIG" to exit the DIAGNOSTIC page, returning your scope to normal operation.

There are many more options that can be accessed in the diagnostic mode.   This is just the straight line path to your requested information.

Let us know your scope numbers.   By the look of the dirt accumulated on the fan, it would appear that it has been operated outside of a clean room environment.   This can and should all be cleaned up.   And the 4 electrolytic capacitors on the A5 board should be replaced ASAP.   It appears that the board around those caps in your photo is still in good shape.   So, count your blessings.   Too often the stuff leaking out of those caps eats up traces and other components in the near vicinity.

My scope indicates over 20,000 hours & 1,100 power cycles.

I'm grateful to you as you saved me a lot of time and eye sharpness for the coming years! I appreciate pädagogical and informative instructions which help one to arive at target.

As for the A8 board, I cleaned it thoroughly and I am going the change all capacitors as I ordered them. I'm going to replace most/ all of the capacitors on the power baord too; these I have to order them from different sources as I couldn't easily find them at one store!
 

Offline SoundTech-LG

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Re: Tektronix 2465B oscilloscope teardown
« Reply #719 on: April 14, 2016, 12:31:46 am »
Great to know about the GQ support folks. I've been searching for a better alternative for my TL866 programmer, which did successfully read/write several of my 246xxx series scopes Dallas ICs, but having issues with some Atmel AT89C51ED2 / AT89C51RD2 MCUs in another project. I don't see those in the GQ-4X4 list of supported devices, (I only see AT89C51).
and have an email to MCUmall to see what they say. Still sounds like a great programmer for the bux.

Thanks for all the info!!


 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #720 on: April 15, 2016, 06:53:31 am »
Update since my last entry on March 7th......

There has been progress and also a major setback.

After replacing all the caps on the supply boards I did a 6 hour “burn-in” to insure all was OK. I verified the 10 VDC reference and it was 10.1 VDC which is in spec. (It was prior to the re-cap too) All the supply voltages to J119 on the main board are in spec (Again, they were prior to the re-cap) The minor drifting issue with the Counter and DMM options is fixed. I performed a re-calibration of the Counter and it's now dead nuts as shown:

Sidelight: The 2465 does not have the EXER 05 and I can't check the power on hours or on/off cycles. And I haven't found any reference in the service manual to access it.

Major setback: I accidentally damaged the front end in the DMM option while attempting a calibration. It now has a solid DC offset error and won't zero. I had originally performed a DC calibration with the required “constants” of 0.19 VDC, 1.9 VDC, 19.0 VDC, and 190.0 VDC. The last “constant” required was 500 VDC. I built up a source to supply this constant. Unfortunately the source had an intermittent connection and it threw a spike into the DMM. I discovered that this DMM option does not have the best input protection and something got FUBAR'ed.       

I verified that all the precision resistors in the input/attenuation network are OK so now I'm going after the active components. Troubleshooting in this area is very difficult because of the high impedances and even a 10MEG DMM loads down the circuit. So I chose the most likely suspects and doing a mass replace. I've sourced all the parts except one op-amp which appears to be unobtanium. Luckily it's further down the chain of components so hopefully it's OK. I'll update after I get and replace the parts.

And finally. I still have this pesky BU Test F1 Fail 10 on power up. It's a Buffer board EAROM checksum error. As near as I can tell it might only affect the GPIB and the Word Recognizer options. I don't use those options so this error is low priority at this time. While going through the cal routines I noticed the ability to calibrate the Buffer board but no mention of it in the 2465 Options Service Manual. But it IS in the 2465A Options Service Manual. So I performed the calibration and on the first power up cycle the error went away. But then it came back. So this needs more work but after I get the DMM fixed. 
« Last Edit: July 18, 2017, 09:38:19 pm by med6753 »
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Offline MarkL

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Re: Tektronix 2465B oscilloscope teardown
« Reply #721 on: April 15, 2016, 08:02:42 am »
...
And finally. I still have this pesky BU Test F1 Fail 10 on power up. It's a Buffer board EAROM checksum error. As near as I can tell it might only affect the GPIB and the Word Recognizer options. I don't use those options so this error is low priority at this time. While going through the cal routines I noticed the ability to calibrate the Buffer board but no mention of it in the 2465 Options Service Manual. But it IS in the 2465A Options Service Manual. So I performed the calibration and on the first power up cycle the error went away. But then it came back. So this needs more work but after I get the DMM fixed. 
Here's the 2445/2465 (plain, not A or B) of the CT and WR service manual if you want it:

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg710773/?topicseen#msg710773
 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #722 on: April 15, 2016, 08:15:18 am »
...
And finally. I still have this pesky BU Test F1 Fail 10 on power up. It's a Buffer board EAROM checksum error. As near as I can tell it might only affect the GPIB and the Word Recognizer options. I don't use those options so this error is low priority at this time. While going through the cal routines I noticed the ability to calibrate the Buffer board but no mention of it in the 2465 Options Service Manual. But it IS in the 2465A Options Service Manual. So I performed the calibration and on the first power up cycle the error went away. But then it came back. So this needs more work but after I get the DMM fixed. 
Here's the 2445/2465 (plain, not A or B) of the CT and WR service manual if you want it:

https://www.eevblog.com/forum/testgear/tektronix-2465b-oscilloscope-teardown/msg710773/?topicseen#msg710773

Thanks. I have all the manuals for the 2465, both the mainframe and the options manual. What is strange is that the calibration routines that appear on CRT give the ability to do a Buffer Board calibration but the 2465 options service manual makes no mention of it. I just happen to have the 2465A options service manual and it does mention it. Either it's an error or most likely I'm missing an update.
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Offline MarkL

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Re: Tektronix 2465B oscilloscope teardown
« Reply #723 on: April 15, 2016, 12:57:39 pm »
...
Thanks. I have all the manuals for the 2465, both the mainframe and the options manual. What is strange is that the calibration routines that appear on CRT give the ability to do a Buffer Board calibration but the 2465 options service manual makes no mention of it. I just happen to have the 2465A options service manual and it does mention it. Either it's an error or most likely I'm missing an update.
The 2445/2465 Option 10 GPIB Service Manual (pub #070-4640-00) mentions that "BU CAL F1" has to be performed before the GPIB cal "GP CAL 11".

But there's no description of exactly what "BU CAL F1" does.  What does it do on the 2465A?
 

Online med6753

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Re: Tektronix 2465B oscilloscope teardown
« Reply #724 on: April 15, 2016, 09:44:04 pm »

The 2445/2465 Option 10 GPIB Service Manual (pub #070-4640-00) mentions that "BU CAL F1" has to be performed before the GPIB cal "GP CAL 11".

OK, I figured out what's going on. The 2465 options service manual I have only covers options 6 and 9. I have a separate 2465 service manual for the DMM (option 1). Do you know of a source for the Option 10 manual?

But there's no description of exactly what "BU CAL F1" does.  What does it do on the 2465A?

The 2465A options service manuals covers all the options. Here's what it says with regards to calibrating the Buffer Board.
« Last Edit: July 18, 2017, 08:58:25 pm by med6753 »
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