Digital Troubleshooting

Preliminary Checks

Instrument Preset Check

The two red INSTR CHECK LEDs light whenever the instrument is turned on or when @Z-Z@ is pushed. The main processor then performs a check of itself, a checksum verification of all ROMs on the Al5 Controller, a partial check of the Instrument Bus (50-wire bus), and a read-write check of the RAMS and A3A4 Memory in the IF-Display Section.

If all the checks pass, both INSTR CHECK LEDs turn off.

If any check fails, one or both INSTR CHECK LEDs remain on.

Both INSTR CHECK LEDs on indicates a problem with the Al5 Controller. First, remove the Controller and make sure that the 50-wire ribbon cable and HP-IB ribbon cable are pressed all the way onto A15Jl and A15J2 connectors. Reinstall the Al5 Controller. If both front panel INSTR CHECK LEDs still remain on when the instrument is turned on, follow procedure under Al5 Controller Self Test.

Left LED (INSTR CHECK I) on indicates a failure occurred when checking the Digital Storage Memory (A3A4). First, check to ensure that a LINE power cord is connected to the IF-Display Section. Also check to see that the rear-panel Analyzer Bus Interconnect Cable, W31, is properly connected. If INSTR CHECK I still remains on when the instrument is turned on, troubleshoot the A3 Digital Storage in the IF-Display Section.

Right LED (INSTR CHECK II) on indicates a failure occurred during the partial check of the Instrument Bus.

Note

The partial interface check reads the key column lines (KC0 through KC7)

 

from the Al and A5 front panels. If any front panel key is shorted or stuck

 

closed, INSTR CHECK II LED should remain on after the Self Test is

 

completed. This part of the Self Test can easily be verified by pushing any

 

key, except CLCL), and holding the key in while pushing (2-22). If the I/O

 

interface check routine is working, INSTR CHECK II LED will stay on.

 

 

nSuspected digital failure but no INSTR CHECK LEDs on may indicate a RAM or I/O bus failure which is not checked in the normal Self Check or “POP” (Power-On Preset). If the two front panel INSTR CHECK LEDs turn on when the LINE switch is set to ON, and turn off again within a few seconds (indicating no digital problems), but symptoms persist (such as improper CRT display or improper response to particular commands) indicating that the problem is in the digital area, a “LONG POP” can be performed.

Digital Troubleshooting 1