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Unable to read NVRAM Contents of a TDS684A


Rogerio O
 

Hi folks,
I have been trying to read the content of the Dallas DS1486 of my TDS684A before trying to desolder it.
The battery is really low since it is necessary to run SPC calibration every time I turn the scope off.
I have tried the tools developed by Madao ( tdsNvramMinimalFloppyDumper and tdsNvramFloppyDumper) but neither is able to produce any dump file.
When using the tdsNvramMinimalFloppyDumper, I tried different timings to turn the NVRAM protection switch to 'unprotected, but could make it work.
If I try tdsNvramFloppyDumper, the floppy led flicks one time but nothing is written to the disk.
There is a problem in this instrument since I get an error when trying to format the floppy on the scope, but I can see the file contents of the floppy and create a new directory in it.
I have tried a second floppy and the results are the same.
My questions are:
1- Since it is possible to read and write to the floppy, why is it not possible to format it?
2- Is there any known issue with this tool with TDS series A scopes?
3- Are there other tools known to work on these scopes?

Thank you,
Roger


Chuck Harris
 

One of the features of the DALLAS NVRAM species is
they disable themselves when the Lithium cell drops
below a certain voltage. They will be remain disabled
regardless of the voltage applied to the NVRAM's VCC
pin, until the Lithium cell voltage is restored.

If you absolutely must have the contents of the NVRAM,
you can sometimes get it by digging out the epoxy around
the + terminal of the lithium cell and applying 3V
between the + terminal and the ground pin for the NVRAM...
then it should read with any EPROM programmer that can
read an EEPROM or CMOS RAM chip.

-Chuck Harris

Rogerio O wrote:

Hi folks,
I have been trying to read the content of the Dallas DS1486 of my TDS684A before trying to desolder it.
The battery is really low since it is necessary to run SPC calibration every time I turn the scope off.
I have tried the tools developed by Madao ( tdsNvramMinimalFloppyDumper and tdsNvramFloppyDumper) but neither is able to produce any dump file.
When using the tdsNvramMinimalFloppyDumper, I tried different timings to turn the NVRAM protection switch to 'unprotected, but could make it work.
If I try tdsNvramFloppyDumper, the floppy led flicks one time but nothing is written to the disk.
There is a problem in this instrument since I get an error when trying to format the floppy on the scope, but I can see the file contents of the floppy and create a new directory in it.
I have tried a second floppy and the results are the same.
My questions are:
1- Since it is possible to read and write to the floppy, why is it not possible to format it?
2- Is there any known issue with this tool with TDS series A scopes?
3- Are there other tools known to work on these scopes?

Thank you,
Roger






EricJ
 

The floppy drives on these scopes are a little picky when it comes to
media. I had no end of trouble finding a floppy disk that would format in
my meager selection. Then I got a box of N.O.S. disks from a friend, and
every single one of that particular type works and formats just fine.

From what I understand, the TDS floppy tools for reading and writing NVRAM
written by flyte from EEVBlog should be able to be initiated from the
floppy utility menu of the scope. I used the reboot method on both my
TDS754A and TDS754D scopes myself, and just flipped the protect switch at
the right time.

--Eric

On Mon, Jan 25, 2021, 12:21 PM Rogerio O <rodd414@gmail.com> wrote:

Hi folks,
I have been trying to read the content of the Dallas DS1486 of my TDS684A
before trying to desolder it.
The battery is really low since it is necessary to run SPC calibration
every time I turn the scope off.
I have tried the tools developed by Madao ( tdsNvramMinimalFloppyDumper
and tdsNvramFloppyDumper) but neither is able to produce any dump file.
When using the tdsNvramMinimalFloppyDumper, I tried different timings to
turn the NVRAM protection switch to 'unprotected, but could make it work.
If I try tdsNvramFloppyDumper, the floppy led flicks one time but nothing
is written to the disk.
There is a problem in this instrument since I get an error when trying to
format the floppy on the scope, but I can see the file contents of the
floppy and create a new directory in it.
I have tried a second floppy and the results are the same.
My questions are:
1- Since it is possible to read and write to the floppy, why is it not
possible to format it?
2- Is there any known issue with this tool with TDS series A scopes?
3- Are there other tools known to work on these scopes?

Thank you,
Roger






Rogerio O
 

Hi Eric,
Thank you for your reply.
I have two questions:
1 - Would you please expand on how can I initiate the utility form the utility menu?
2 - The led on my floppy just stay on for a brief period and just one time.
I do not understand what people say "flip the switch just after the led turns on for the first time"
Can you remember what was the "right time" for your machines?
Thank you.
Roger


EricJ
 

Hi Roger,

You're welcome. I will investigate later today and see if I can figure out
the exact steps to use the disk utility menu for you. The instructions for
the floppy tools utility regarding flipping the NVRAM write protect switch
were not very clear, I agree with you there. It was some time ago that I
did the read/write on my scopes but I believe that I flipped the switch off
as soon as I heard any drive activity on the first boot, then back on as
soon as the scope restarted and seemed to finish writing to the disk or
NVRAM, depending on process. It was a little tricky to get right, and I
think it took me a couple tries to get the write done correctly. I know it
worked, as the time on the scope reset to the time when I did the read and
I also added an option via NVRAM editing which the scope didn't have
originally. I believe that was option 3C. I will update a little bit later
after I've had a chance to get into the disk utility menu.

--Eric

On Tue, Jan 26, 2021, 9:51 AM Rogerio O <rodd414@gmail.com> wrote:

Hi Eric,
Thank you for your reply.
I have two questions:
1 - Would you please expand on how can I initiate the utility form the
utility menu?
2 - The led on my floppy just stay on for a brief period and just one time.
I do not understand what people say "flip the switch just after the
led turns on for the first time"
Can you remember what was the "right time" for your machines?
Thank you.
Roger






David Slipper
 

Hmmm ... I wasn't aware of tools to dump the NVRAM to floppy --- where are they available for down load ??

Would they work on a TDS 744A ??

as an alternative to floppy (if they proove tricky) can it be dumped via HPIB ???

Regards,
Dave


Rogerio O
 

Hi Dave,
Yes you can dump the NVRAM contents using GPIB.
I have used a program called Tektool ( version V.5) developed by Madao.
Search EEVBlog for it.
I run the program from a DOS windows (with admin privilege) opened in a WIN10 computer and an GPIB/USB adapter.
No need to use old computers with PCMIA cards and earlier versions of Windows.
With this setup I was able to dump the NVRAM .contents of a TDS784D and a TDS684A.
However these dumps have not been "tested" yet since I am waiting for a GQ 4x4 programmer to arrive.
There is another trend where someone was able to program the DS1486 used on these scopes with this programmer, using the DS1245 chip configuration.
I tried once using the TL866A programmer but it didn't work, however the target chip was a fake Chinese crap, so I can't tell what was causing the failure.
I am waiting for Eric J instructions on the switch flipping "magic" since I am not been able to make it work on the 1.1e firmware of the TDS684A.
What is the firmware version of your TDS744?


David Slipper
 

Interesting --- I have found all the relevent bits and pieces of software.  I really aught to backup the EEPROMs and NVRAMs sooner rather than too-later.

I have no idea of the firmware rev ... how can I find out ??

Is there a repository of firmware dumps somewhere ??

I have written programs in FreeBasic to perform screen dumps via HPIB and looking at the sources above I should be able to do much the same for the NVRAM and EEPROM

Regards,
Dave

On 27/01/2021 22:40, Rogerio O wrote:
Hi Dave,
Yes you can dump the NVRAM contents using GPIB.
I have used a program called Tektool ( version V.5) developed by Madao.
Search EEVBlog for it.
I run the program from a DOS windows (with admin privilege) opened in a WIN10 computer and an GPIB/USB adapter.
No need to use old computers with PCMIA cards and earlier versions of Windows.
With this setup I was able to dump the NVRAM .contents of a TDS784D and a TDS684A.
However these dumps have not been "tested" yet since I am waiting for a GQ 4x4 programmer to arrive.
There is another trend where someone was able to program the DS1486 used on these scopes with this programmer, using the DS1245 chip configuration.
I tried once using the TL866A programmer but it didn't work, however the target chip was a fake Chinese crap, so I can't tell what was causing the failure.
I am waiting for Eric J instructions on the switch flipping "magic" since I am not been able to make it work on the 1.1e firmware of the TDS684A.
What is the firmware version of your TDS744?




EricJ
 

OK, earlier I mentioned using the disk 'Utility' menu to run the app but I
was having a little CRS moment. Actually it's not the regular disk utility;
you need to run the floppy app from the 'SETUP' menu. So boot the scope as
normal until it's completely done. Clear menu, etc. Insert your floppy with
the 'NVRAM read' file on it. Flip the write-protect switch to off. Hit the
'SETUP' button, then hit the 'Select Application' softkey at the bottom of
the screen, then use the wheel to select the app and hit the 'SELECT'
button next to the wheel. That should run the file for you. When the scope
shuts down to reboot, eject the disk and flip the write protect switch back
to on.

There is at least one thread at EEVblog on these utilities:

https://www.eevblog.com/forum/testgear/tektronix-tds500600700-nvram-floppy-dump-tool/50/

There was some discussion about the NVRAM utilities there perhaps not
working with either very early or very late firmwares as I recall.

--Eric

On Wed, Jan 27, 2021, 4:41 PM Rogerio O <rodd414@gmail.com> wrote:

Hi Dave,
Yes you can dump the NVRAM contents using GPIB.
I have used a program called Tektool ( version V.5) developed by Madao.
Search EEVBlog for it.
I run the program from a DOS windows (with admin privilege) opened in a
WIN10 computer and an GPIB/USB adapter.
No need to use old computers with PCMIA cards and earlier versions of
Windows.
With this setup I was able to dump the NVRAM .contents of a TDS784D and a
TDS684A.
However these dumps have not been "tested" yet since I am waiting for a GQ
4x4 programmer to arrive.
There is another trend where someone was able to program the DS1486 used
on these scopes with this programmer, using the DS1245 chip configuration.
I tried once using the TL866A programmer but it didn't work, however the
target chip was a fake Chinese crap, so I can't tell what was causing the
failure.
I am waiting for Eric J instructions on the switch flipping "magic" since
I am not been able to make it work on the 1.1e firmware of the TDS684A.
What is the firmware version of your TDS744?






Rogerio O
 

I could not locate the soft button “select application”.
My firmware version is 1.1e.
Can anyone confirm there is such a button in this firmware version?
Thanks