I’m repairing a HP 4726A LCZ meter. The digital troubleshooting section refers to reading HP Signature Sets using a HP 5004A. I’m assuming these are basically unobtainium. Is there a way of calculating the signature sets without one?
Caveat: I last looked at signature analysers when they first came, i.e. ~45years ago. I recall all they could do is tell you whether the signals on a node were
precisely the same as those in a known good "golden" device. If there was any deviation, they gave zero information about what might have caused it.
Hence they are only useful to tell a repair technician which module to replace. I was never in that position, so I never had occasion to use a signature analyser. I doubt you are in the position of being able to replace a module

In any old instrument, the strategy is to carefully look at all components and switches, to see if there are any gross failures. If not, then check all the power supplies are correct, both voltage and ripple (electrolytic capacitors are a standard problem, and don't forget the RIFAs!). Beyond that, intuition and understanding the specific schematic and are useful
