SPC fails on TDS7404


I just got a TDS7404 scope that seems to be working well EXCEPT that it always fails the signal path compensation routine (yes, the scope has completed the warm-up before I start the SPC routine). All the other self-tests pass consistently. I haven't been able to find any relevant troubleshooting information in the Tek manuals. Is there a particular point of failure in these scopes that might account for this?


Erkka Sointula

Hi Stan,

My TDS7404 has the same problem.
It has a special IC with a x-tal, Lithium battery and memory built in.
When the battery goes empty then also some cal values in the memory.
Based on some experts the only way to get it back is send it to Tek. Price ?

I have 8GHz high end Anritsu VNA with the same problem\circuit and it does not even boot up.

Your TEK might still be good for your own use. Check just the amplitude levels and freq response. They might be good enough.

br Erkka

Charly Marina

Hi stan i would look in your inputs.. if one of the input is not good/out of spec.. you can get an spc fail also.