HP 8560E Service Manual page 495

Controller Section
Video Input Scaling Amplifiers and Limiter (8560EC)
9. Disconnect the CAL OUTPUT signal from the INPUT 50Ω
connector.
10.The level at pin 3 of U10 should drop to −0.35 Vdc. If the level is less
(more negative) than −0.35 Vdc, replace voltage clamp D3.
11.Measure the dc level of the flash video at pin 2 of R47. The level
should be near 0 Vdc with the signal at the bottom graticule line (no
input to the spectrum analyzer).
12.Connect the CAL OUTPUT to the INPUT 50Ω connector.
13.Measure the dc level of the flash video at pin 2 of R47. The level
should be near +1.7 Vdc.
494 Chapter 9