Re: TDS 684A needs recapping?


Siggi
 

On Mon, Sep 14, 2020 at 8:52 AM Sigurður Ásgeirsson <siggi@undo.com> wrote:

On Sat, Sep 12, 2020 at 10:06 AM Rogerio O <rodd414@gmail.com> wrote:

Concerning the NVRAM, I have read conflicting information about loosing
the calibration if I replace it.

The calibration data is stored in the acquisition board in EEPROM per the
service manuals, which makes sense for board-level serviceability.
Hey Roger,

I'd like to amend my statement here, as I'm likely wrong about this as far
as concerns your scope. I've just downloaded the TDS NVRAM saver
application from this EEVBlog thread:
https://www.eevblog.com/forum/testgear/tektronix-tds500600700-nvram-floppy-dump-tool/.
According to the information in there, the B/C/D-series scopes have an
EEPROM for calibration data on the acquisition board, whereas the earlier
scopes stored the calibration data in NVRAM.
I'm guessing this is the source of confusion - not all the TDS5/6/7XX
scopes are the same in this respect, whereas people (like me) assume they
are.

There's an info.txt file in the archive with a description of the various
tools, where it says:

"tdsAcqEEPROMFloppyDumper and tdsAcqEEPROMMinimalFloppyDumper:

Dumps the contents of the calibration constants 24C02 EEPROMs located
on the acquisition boards of the -B, -C and -D series scopes, to a file.


*-A series scopes have no such EEPROMs on the acquisition board andstore
these constants in regular NVRAM, albeit in a hardware-protectedregion*.
Both 24C02 EEPROMs are read as 0x200 bytes in a single file,
where the first EEPROM is the top 0x100 half of the file, and the second
one the bottom half."

Siggi

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