Rybett Controls WebDoc 101 (Copyright 2008) Return to [Index]
When a system stops working, recent events may hold a clue to the cause and cure of your problem. Some typical causes follow:
1. A lightning storm or power surge damaged hardware. DNC cables are easy targets for lightning and may conduct power surges between machine and computer ports. Examine WebDoc 102 for more information on testing and repairing your DNC communication ports.
2. A repairman altered machine connections or settings. In the process of repairing a machine, factory servicemen often disconnect DNC/BTR hardware. Refer to your original installation instructions and reconnect the hardware. Also, machine settings may be altered if boards are swapped or parameter tapes reloaded. A very common change affects the EIA/ASCII tape format which will affect BTR operation. The EIA/ASCII setting on Rybett BTRs may be changed as follows: Camstore 1 or Exec (Press <Ctrl> A or <Ctrl> E), Camstore 2 or COM (Flip DIP switch position 5), Camstore 1SX or LPT (Alter Machine Setup "Format").
All Rybett BTR tape reader interfaces may be placed in a BYPASS condition enabling operation from the reader as if the BTR were not installed. This can be a good test of the BTR interface card. For more information on BTR interface testing, go to WebDoc 108.
3. Someone added hardware to your computer. DNC systems typically use a COM port for communication. Port COM1 uses an interrupt signal called IRQ4 while COM2 uses IRQ3. Make sure that new cards do not share your DNC interrupt. Note that extra ports COM3 and COM4 also use IRQ4 and IRQ3. If your DNC uses COM1, don't add a mouse or modem to COM3. If your DNC uses COM2, don't add anything to COM4.
4. Someone (maybe you) added new software to the DNC computer. If only software was added, check the DOS autoexec.bat and config.sys boot files for any changes. Mouse and network drivers that reference COM ports or IRQ signals can cause problems even if the hardware is not installed. You may add "rem" to the beginning of any suspicious lines in your boot files to temporarily remove them for testing. For safety, copy your working boot files to new names, say "autoexec.ok".
5. The DNC computer was recently used to test programs of unknown origin. Perhaps a computer virus has infected your system. Buy a current release of a virus scanning program and pray. If you have a virus, you must carefully inspect all computers and all floppy disks.
6. Don't overlook the obvious (which can be easy to fix). Make sure all cables are properly seated on the correct connectors. Trace all wiring to make sure nothing has been stretched, nicked or cut.