GAMMA Glitches: Symptom Summary

Gamma Glitches

( When 2 fixes are suggested, fix #1 is suggested for the general user; fix #2 is suggested for those more familiar with the hardware. )
Symptom:
The shutter closes every 30 seconds during scan setup
Cause:
A software bug. Will be fixed in build 2.3.
Workaround:
Before starting the scan, use command_sac and select initialize to std config (from loaded memory) . This will reboot the servo (which loses the fiducial) and disarm the 30 second shutter timer.
Symptom:
The displays in rm 133 "hang" & don't respond to updates during a scan.
Cause:
The LTA terminal server is in a strange state.
Fix:
Cycle power on the LTA terminal server box by unplugging its power cord, waiting 5 seconds, then plugging it back in again. The LTA terminal server box is labelled near the relevant black power cord. The LTA controller "octopus", which is what the displays are actually connected to via telephone-like wires, is also labelled. You can get from the "octopus" to the box by following the thick SCSI-looking cable. As of this writing (5/24/96), the "octopus" is under the ops desk, and the box itself is on the laser printer cart, with the power cord easily accessible if you're standing just inside the door to rm 133.
Symptom:
  • ALIA hangs when moving to start position for raster
  • The SRQ light is not on
    • Cause:
    The servo can't quite get it there. Probably the servo motors need to be balanced.
    Fix:
    Give the carriage a tap.
    Symptom:
  • ALIA has byte count errors on the first pass that it does not recover from
  • It gets only a few hundred or a thousand bytes, instead of what it should
  • The PPG status word is 432 or 416.
  • The empty light on the FIFO stays on until the end of the pass, instead of going out near the beginning
  • The "NO" light (indicating no 1/N pulses being received) on the PPG stays on till the end of the pass.
    • Cause:
    The count register in the scaler has been left in a strange, non-empty state. (Perhaps a scan was aborted in midline somehow.)

    Click here for a walkthrough of the diagnostic procedure for this sort of problem.

    Fix:
    Before issuing the scan command, press the reset button on the scaler module in the CAMAC crate
    Symptom:
  • ALIA hangs when moving to start position for shading raster
  • Tapping the carriage doesn't help
    • Cause:
    Unknown. Please call Vicki next time it happens.
    Workaround:
    ^Y , stop, restart servo box, and start over
    Symptom:
  • ALIA dies before shading raster
  • SAC does not exist
    • Cause:
    Unknown. Please call Vicki next time it happens.
    Workaround:
    ^Y , stop, and start over
    Symptom:
    Update of density display extremely slow during setup
    Cause:
    Unknown. Please call Vicki next time it happens.
    Workaround:
    Raising SAC process to priority 5 might help. Otherwise, ^Y , stop, and start over
    Symptom:
  • ALIA won't move at all when moving to start position for raster
    • Possible cause:
    The servo doesn't actually have control of the table.

    Check that the auto/manual switch is in auto; that both x and y motor switches are ON; and that the overall motor on/off switch is ON.

    Caution:
    If this is indeed the case & you turn on the motors at this point, I am not sure whether the table will behave normally, or whether it will start rushing at full correction speed to the desired position.

    If the problem is that the auto/manual switch was still in manual, you will almost certainly have to abort and restart the scan.

    Symptom:
  • ALIA scan dies at end of first pass
  • Error message refers to error in laser monitor read
  • "SMP" light is lit on transient recorder
    • Cause:
    The control register on the transient recorder hasn't been initialized. (Perhaps the crate was powered down.)
    Fix:
    #1: Run the program alia_exe:command_sac and select "initialize to standard configuration."
    Fix:
    #2: Use hw_idl to, first, make it stop digitizing _immediately_, and second, write the decimal number 17807 to the control register. Refer to the manual for the transient recorder to get the correct F and A commands. Read the control register back before proceeding to make sure it went in correctly.
    Symptom:
  • ALIA scan hangs at end of first pass
  • SRQ light is not lit on servo box
    • Cause:
    The IMSK register in the servo hasn't been initialized. (Perhaps the servo box was powered down.)
    Fix:
    #1: Run the program alia_exe:command_sac and select "initialize to standard configuration."
    Fix:
    #2: Use hw_idl to set IMSK to 1. Read it back before proceeding to make sure it went in correctly.
    Symptom:
    Console buttons are unlit, high voltage display is blank
    Cause:
    The module controlling the console hasn't been initialized. (Perhaps the crate was powered down.)
    Fix:
    #1: Run the program alia_exe:command_sac and select "initialize to standard configuration."
    Fix:
    #2: Use hw_idl to send the value 36 to the module. Refer to the manual for the OR-4 device to get the correct F and A commands.
    Symptom:
  • Stand alone console dies immediately after being run.
  • If there is a log file, it says "PORT ASSIGN ERROR."
    • Cause:
    Some other process has the servo port allocated - probably an IDL process.
    Fix:
    Exit the IDL process, and do a set proc/priv=share. Then start the SAC again.
    Preventative:
    Always do set proc/priv=share before getting into IDL, and never write code that doesn't open the port shared.
    Symptom:
  • Stand alone console dies after booting
    • Cause:
    Possibly a software logic error
    Workaround:
    Just keep trying. It usually works on the 2nd or 3rd try.
    Plans for fix:
    Vicki will make some changes in the next build.
    Symptom:
  • Stand alone console dies after power outage reboot
  • The file alia_data:sac.log contains error messages referring to qio errors.
    • Cause:
    The Micro488a IEEE controller (black box connected to servo port) was left in a strange state.
    Fix:
    Get into hw_idl and do ieee_init . This should properly initialize the device. Then try starting the SAC again.
    Symptom:
  • The shading numbers are coming up 0 in density, 1 in transmission
  • Dumping the VIM file shows it to be nearly all 0s.
  • Dumping the RAW_VIM file shows it to be ok.
  • Dumping the LASER_LOG file shows it to be full of numbers on the order of 160.
    • Cause:
    The sensor for the laser monitor is unplugged.
    Fix:
    Plug it back in, then wait a couple hours for it to settle. NOTE: To dump the files, do dump/dec/rec/word .
    Symptom:
  • The VIM file is coming up entirely dark
  • No laser spot is visible on the plate.
  • The frequency is in the correct domain.
    • Cause:
    The cable controlling the shutter is loose & has fallen out of contact on the crate module.
    Fix:
    Wiggle the cable to get it seated better.
    Symptom:
  • "SMP" light won't go out on transient recorder
  • Fixes #1 and 2 to initialize the control register of the transient recorder won't work.
  • Sending 17807 to the control register and then reading the control register doesn't give you 17807 back.
    • Cause:
    The control register on the transient recorder/memory module pair is hosed in some way.
    Fix:
    We're not entirely sure, but try removing the module and reseating it... Last time we sent it to the factory and it worked when it came back, but they didn't do any repairs to it.
    Symptom:
  • No "internal reads" during pass
  • FIFO shows no activity during pass
  • FIFO fills up (FULL light comes on) before pass is over
    • Cause:
    First pixel event flag is not going off, because "not empty" LAM is not enabled on the module.
    Fix:
    Put the SAC to sleep, if it is awake, and pull the FIFO module (after powering down the crate and removing the data cable from the module). Near the bottom front of the board, there is a jumper with two possible settings, EXT and NOT EMP (which stand for External and Not Empty). Set the jumper to the NOT EMP setting. Replace the module & cables & power the crate back up. Remember to reinitialize the SAC (using command_sac or fill_servo_coeffs) before proceeding.

    Vicki Laidler -- laidler@stsci.edu
    Last updated 12/17/96