HP 8559A - 8-85

MODEL 8559A SERVICE
Auto Scan Time (AST) Accuracy:
Observe front panel switch positions to isolate the problem area. Auto
scan time can also be affected by circuits on the Sweep
Generator/Bandwidth Control Assembly A9 and the
VIDEO FILTER control position. If the AST problem is band
- related, the Marker Assembly A8 is the most
probable cause. If the AST problem is either bandwidth
- or scanwidth - related, the most probable cause is the
Sweep
Generator/Bandwidth Control Assembly A9. The greater the load on the AST line, the greater the
current demand. The greater the current demand, the faster the sweep rate.
Residual FM:
Residual FM can originate from the Second LO Driver (block E). The most common failures
are: R88, R87, R33, R34,
U1, U7, R37, and R38, in that order.