HP 8560E Spectrum Analyzer Repair. No input signal displayed. Solved.

[4thDoctorWhoFan]

This post is to help anyone who might have a HP 8560E spectrum analyzer.  The fault is the analyzer will not display any input signal including the calibration input signal.  You will also have numerous errors like 355, 351, 353, 319, 317, 356 and 335. Your mileage will vary.  Might have less or more errors.

In 8 months, I bought two different 8560E analyzers off of ebay from different sellers.  Once I received them and checked them out, both had the symptom listed above.  I bought the second one because the display was still nice and bright compared to the first one I purchased and it was cheap.  These analyzer are known for having dim displays.  Anyway, both units had the same symptom of no input signal showing on the screen and it turned out that both had the same faulty part.

Bottom Line:  Go to the A15 board and look at the J701 output.  Should be 600Mhz AND around -3dbm to +5dbm.  Both of my units were spot on 600Mhz BUT the levels were around -20/-25 dbm.  After some troubleshooting, the problem was U700.

After replacing U700 on both units, the errors went away and the analyzer worked as it should.  U700 is just a RF amp on the A15 board.  It's under one of the metal shields/heatsinks in the 100Mhz distribution section.  The 100Mhz gets doubled, then tripled to 600Mhz.

U700 is a MSA-0505.  I purchased genuine HP parts from a seller on ebay from Israel.  There are others from China but who knows if they are genuine.

Anyway, good luck and hope this helps get your analyzer up and running again.  Since I had two units with the same fault, I thought it might be a common problem and help others.

[bitseeker]

Thanks for the info. Mine doesn't suffer from this (yet), but good to know in case it shows up later.

[tchiwam]

Note to add here:

   I just found out the same trouble. Mine has :

U700
+9 dBm input
+14dBm output

This is taken with a 84025A and another spectrum analyzer.

The rest of the chain to the 300 and 600Mhz is also low...

>> The symptom is that I loose ~10dB sensitivity from DC to about 6GHz. on a 8563E <<

I am ordering some from eBay right now. Would be fun to see if other amplifiers could replace that unit, it is a high gain unit nearly +8dB at 100MHz. I think they overdrive it a little the DC on the input is close to 12V instead of +8VDC or +9VDC