Hi,
I was fortunate enough to stumble, one day, upon a HP 8593E SA left in a dumper.
First thing I noticed was it wouldn't keep the time across power cycles and would always start with default settings.
That was easy to troubleshoot and fix - the CR2477 battery solered on the memory board had died and needed replacement.
Following that, I tried to perform a frequency and amplitude self-calibration, which failed with no calibration signal found.
Checking the CAL OUT output, the signal is there, it's at roughly 300 MHz (as it should be), and at the right power level (harmonics too).
Still, when connecting CAL OUT to the INPUT, I see absolutely nothing at or around 300 MHz.
Going through the service guide and test procedures, I found that the +10V and -10V reference detector tests fail (I get the same looking ramp for both +10V and -10V, instead of what the guide indicates there should be).
Also, the FM coil driver test for SPAN below or at 10MHz fails as well (I get a horizontal line, instead of the ramp in the guide).
The other tests I was able to run were all ok.
Now, where I got stuck is the verification of the +10V and -10V references.
According to the manuals, those are being generated on the A7 analog interface board.
However, looking through the CLIP manual, at the schematic for the A7 board, in the area called Voltage References, I can't figure out where those reference outputs reside.
Could someone please confirm whether they are the outputs of U32 and U29, respectively?
If so, what is the reference ground for those?
Is it the chassis ground or something else?
Thanks,
George