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Chapter 13 - Trouble Shooting

Disc Drive Problems

Disc drive problems generally arise from defective or full floppy discs, more rarely from internal hard discs. The following points will help avoid trouble:

The following section indicates how you can correct disc drive problems signalled to you by program messages at various points in the program.

Main Menu Information Panel

The following message relating to disc drive problems can appear in the main menu information panel:

Take main menu selection 3 "Disc Drives and Drive Lists ..." to

access the Drive Operations Menu, to get more information.

Drive Operations Menu

The status panel of this menu carries information and helpful suggestions:

After changing discs and / or reformatting, use selection 1 "Retry ... " to leave the menu and save any data outstanding, or selection 5 "Quit to main menu" to abandon any data outstanding.

Drive List Menu

Alternatively, use selection 3 of the Disc Drive Operations Menu "Drive Lists ... " to access the Drive List Menu, and edit the DATA drive to specify another drive from either drive list. See Chapter 8 - Disc Drives and File Management, if you wish to extend the drive lists.

Other options

Despite any disc or directory problem, it is always possible to select selection 1 of the main menu to set the run and / or instrument parameters and even to attempt a run, though of course the resulting Charge Decay Data cannot be saved.

If selection 2 of the main menu is taken when the drive is empty or the disc unformatted, you are lead straight to a Drive / Directory Selection Menu instead of a File / Directory Picker. From this menu the DATA drive may be selected. You may then quit and if the disc in the new drive is ok you will see the File / Directory Picker as usual, allowing you to pick a file for review. You may also use this method instead of the Drive List Menu to select another drive and directory for recording Charge Decay Data.

Failure to save analysis or graph screens.

During analysis (Chapter 11) an attempt may be made to append analysis data to the report file produced for the Charge Decay Run, and / or to produce a graph file for subsequent printing of batches of graphs. If there is insufficient room on the disc for these, or the disc has been removed etc., there will be a message detailing the problem, which will appear for up to 20 seconds, or can be terminated with the return key.

The information lost can always be regenerated by re-analysing. This problem is most unlikely to occur on a hard disc. When it occurs with a floppy disc, the solution is to use the file management utility to copy the complete directory to another disc, with some some spare space, and restart the analysis.

Failure to load a Charge Decay Data file for review

If a disc has become corrupted, a file whose name appears in the Data panel of the File / Directory Picker may fail to load. You must use the services of a specialist in disc repair to overcome this problem. But first ensure that the disc has not been inadvertently changed or removed from the drive while the File / Directory Picker was on screen!

Serial Link Problems

Serial link problems tend to arise due to incorrect configuration when this software is first used, and on subsequent occasions due to hardware failures. Configuration problems can be eased by identifying serial port Nº 1, and using this for the JCI155v4 instrument.

The following points can help in ensuring first time success with the serial link:

Main Menu Information Panel

The following message relating to serial port problems can appear in the main menu information panel:

Take main menu selection 4

Port / calendar / setup directory ...

to access the Serial Port Setting. Two of the 4 items are relevant to the serial port.

Figure 14.1 - Serial Port Setting

Changing the serial port setting

Select the Serial Port Editable Item as shown. A right or left arrow head next to the Port Nº will indicate if more than one port is available, and then another port may be selected using appropriate orkeys.

The IRQ Number

This editable item has been included because not every IBM compatible computer uses the same IRQ numbers for each port. In this program, the IRQ numbers default as in the Table Figure 14.2 as follows:

Table 14.2 - Default IRQ Nº Table
Computer Type Ô PC, XT AT
Processor Ô 8088,
80186
80286 / 386 / 486
Pentium
Port Nº 1 Irq3 Irq4
Port Nº 2 Irq4 Irq3
Port Nº 3 Irq3 Irq4
Port Nº 4 Irq4 Irq3

If all else fails, select a new IRQ Nº from those available. If you are using port Nº 1 or 2, try swapping first between IRQ Nºs 3 & 4. The try Nº5, then Nº 2. If these do not work then it is possible that the IRQ Nºs have been reassigned using the computer's internal DIP switches, and you will have to consult the engineer responsible.

If you are obliged to use Port Nº 3 or 4, then you should consult the engineer responsible for installing these extra ports.

Charge Decay R un Start Problems.

The start of a Charge Decay Run can be affected by two problems:

Failure to start

It can sometimes happen that a Charge Decay Run can fail to start, indicated by the Initial Graph Screen hanging in the 'Ready to Run' state, as shown in figure 2.4. The word "Run" appearing at the foot of the screen fails to change to "Running". This occurs when the surface potential of the sample fails to exceed either of the thresholds set by the Run Parameters Menu (figures 2.2, 10.1). Pressto escape from this state.

Corona Parameters

The obvious remedy is to increase the Corona Voltage and / or Duration, either at the JCI155v4 instrument controls (Corona) when in manual operation mode, or from the Instrument Parameters Menu when in computer controlled mode. It might also be appropriate to change the JCI155v4 Corona Polarity to -ve, as the corona discharge is more effective in this mode.

Threshold Levels

Reduction of the threshold level may be necessary on difficult samples, where the effective time constant is less than the effective plate release time. It is wise to only reduce the threshold for the expected polarity of the discharge, to minimise the possibility of a premature start. The threshold can be reduced to as low as 5 volts. Below this level the likelihood of electrical noise / zero drift causing a premature start is too great.

Premature Start

Premature starts are due to either:

In either case one or both of the thresholds set by the run parameters menu (Figure 2.2, 10.1) can be increased; in the latter case, restriction of sample movement may be desirable.

Graph Printing Problems

It is assumed that the printer is physically ok, i.e. it works with other software, and can print graphics.

Satisfactory printing from screen relies upon the MS-DOS® GRAPHICS command having been executed with an appropriate printer-parameter. Unfortunately when this command has once been executed initially with a printer-parameter, then it cannot reliably be expected to work again; but experience has shown that if it is first called without a printer-parameter, then subsequent calls with different printer-parameters work properly.

To get graphics printing working it is necessary:

Setting the printer-parameter

Ensure that the current drive and directory is root of the disc on which the program was installed, then enter the following command at the prompt:

A:>setprint <printer-parameter>

A:>

If no parameter is required then use "G" to get the GRAPHICS command alone. (if no GRAPHICS command at all is required, use "N" to remove it).

Ensuring the command will not be defeated

Normally the GRAPHICS command is first executed from a line in the AUTOEXEC.BAT file used by the computer at boot-up, but such commands may also subsequently be made from the keyboard and from batch files used for starting other programs. However, if the AUTOEXEC.BAT file is examined using MS-DOS® system editors such as EDLIN or EDIT, then any initial call to GRAPHICS can be found, and if it has a printer-parameter, then it may be preceded or replaced by a GRAPHICS command without such a parameter. If it has no such call, then adding a call to GRAPHICS with no printer-parameter will prevent any further problems.


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