HP8594E: CAL not possible because reading is 100MHz off!

[Bicurico]

Hi,

My HP8594E (one of three) is out of CAL, but I cannot run the CAL routine, because it does not find the 300MHz signal. This signal is currently at around 200MHz!

The problem lies within the motherboard, as I have swapped virtually all other components and the problem remains.

I hope it is just like a capacitor that went bad, but that is wishful dreaming.

The spectrum itself is rendered correctly, I can see the same spectrum as on the other working unit. It is just the frequency reading that is wrong. The AMPL calibration needs to be run, too, but thats another story,

Any advise would be welcome.

Thanks,
Vitor

[Bicurico]

I do get "ADC-GND FAIL", too.

[MarkL]

I don't know what relation the frequency error would have to the ADC-GND FAIL, but I think you could start by digging into why you have that error.

There are several pages in the Assembly Level Repair manual on troubleshooting that specific error, including some power supply tolerance checks.  Page 615:

  http://www.keysight.com/upload/cmc_upload/All/08590-90316.pdf