Tektronix TDS644A failed NVSRAM Backup

[toby_muc]

Hi everyone,

as this is my first post on the forum let me quickly introduce myself! My name is Toby, I am from Munich in Germany and although I studied electrical engineering back in the day I do electronics only as a hobby. I stumbled across EEVBlog on Youtube a few months ago and really enjoy watching the videos and reading through the forum. I even started to build a power supply for the first time

But I have one problem I really could need help with:

A couple of years back I got hold of a Tektronix TDS644A DSO which is (at least it was until I screwed things up) in good working order. After opening it up I found the backery-backed NVSRAM and decided to do a backup as recommended somwhere on this forum, as it certainly had reached it's shelf life some 15 years ago. I unsoldered the DS1650Y, copied it's contents and put it back into the scope. Should have been an easy task, but now the scope shows two errors right after start-up:

- FAIL ++ Processor
- FAIL ++ Cal initialization (see error log)

After clearing this messages the scope does work, but shows quite a large voltage offset, about 50mV on the 100mV range with different offsets on the different range settings.

No comes the funny part: I can't get into the error log, because to get there, I have to move the selection in the Utility menu accros "Cal". And there I get a lot of "bing" sounds and the attached error message. The signal path compensation, which might solve my problem, is also hidden behind this error message, so I can't do that either.

Does anyone of you have an idea what went wrong?

Thanks for your help!

Regards,
 Toby.

[andy2000]

Have you tried the secure erase option?  That will reset everything to the defaults, and might clear the conflict. 

[seronday]

The NVRAM has been corrupted.

This exact same thing happened to me with a TDS524A after de-soldering and doing a read of the NVRAM contents.
There is some information on this subject on a TEK forum
https://forum.tek.com/viewtopic.php?f=568&t=135169&p=271724&hilit=%3A+TDS540+NVRAM+error+DS1245#p271713

If you do a search for TDS5xx, TDS6xx NVRAM problems you will find quite a bit of info.

Some people have successfully removed the NVRAM, copied it and put it back in. Other people have had the problem of corrupted NVRAM contents.

Regards.

[toby_muc]

Thanks, I'll head over to the Tek-forum

I shouldn't have touched it ...   

Regards

[Armadillo]

You would need to determine whether your desoldering job was a good job or very badly done?
Cause you may have broken the vias or tracks or caused heat IC damage.?
Desolder it out, repair the vias or tracks or replace the nvsram.
But I don't think the desoldering was that hard for this board.