Appendix C


The PX-8 uses two sets of batteries. The main batteries are used to provide power for running the PX-8. The back-up batteries hold programs in memory when the main battery voltage falls below a useable value.

This appendix covers points related to charging, switching off and removing the batteries, and replacing them.

Some precautions on using the batteries are given in section 2.1.2. To prevent the batteries running down during transportation or storage, the batteries are disconnected during shipment. Your dealer will normally connect them and in-itialize the PX-8. Otherwise follow the procedures outlined in Chapter 2.

C-1 Charging the Batteries

When the main battery voltage falls below a useable value, the message:

CHARGE BATTERYwill appear on the screen and the LEDs at the top of the keyboard will flash. The PX-8 will then use the backup batteries to preserve the programs and data in memory. If it is convenient to use the AC adapter, the PX-8 can be used while the batteries are being charged, although they will take longer to charge.

IF NO DISPLAY IS VISIBLE WHEN THE COMPUTER IS FIRST SWITCHED ON, the batteries may be discharged. The other possibility is that the view angle of the LCD screen may be set incorrectly. When the AC adaptor is plugged in, the batteries may be so low that not enough power is available to allow the PX-8 to operate and to charge the batteries. In this case no display will appear. Wait 10-15 seconds and switch the main power on again with the AC adapter inserted.


The batteries will take about 8 hours to charge if the PX-8 is not in use. To prevent overcharging the batteries will trickle charge after 8 hours. If the bat-teries are being charged while the computer is in use, the batteries may not be-come fully charged. Thus charging should be repeated for at least 8 hours after a session in which the PX-8 has been used with the AC adapter attached. This charging should be carried out as follows:

  1. Switch the main power switch to the OFF position.
  2. Remove the AC adapter plug.
  3. Replace the AC adapter plug.
  4. Charge for 8 hours.

C-2 Problems with Recharging

If the PX-8 has been left for an extended period of time, the backup batteries will continue to be charged from the main batteries. At some stage the voltage of the backup batteries will reach a level below which it is not possible to restart normal operation of the PX-8. In this case proceed as follows:

  1. Charge the batteries with the AC adapter for 10 - 15 seconds.
  2. Turn the main power switch on the side of the PX-8 to the ON position.
  3. If normal operation does not occur, open the cover to expose the DIP switch and 7508 sub-CPU reset switch.
  4. Press the sub-CPU reset switch, and the initialization message should ap-pear on the screen as described in section 2.1.3.
  5. If nothing happens at this stage, consult your EPSON dealer.

C-3 Switching off the Batteries during Extended Storage

If the PX-8 is.not used for an extended period of time the battery charge will gradually be reduced as the power is used to charge the backup batteries. If this continues for too long, the battery will become overdischarged. This can cause deterioration of the battery. In extreme cases, after a very long time, it can result in the batteries leaking and damaging the computer.


If the PX-8 is to be left unused for a period of sixth months or more, the bat-teries should be switched off and disconnected as follows:

  1. SAVE ALL PROGRAMS AND DATA ON TAPE OR DISK. All programs and data in memory, including the RAM disk and Intelligent RAM Disk will be lost when the batteries are switched off.
  2. Switch the backup battery switch to off.
  3. Open the battery cover (Fig. C.1) and unplug the main battery lead.
  4. Replace the cover.
Fig. C1 & C2


C-4 Connecting the Batteries after Extended Storage, or on Purchase

Connection Sequence:

  1. Check that the power switch is set to the OFF position.
  2. Turn the PX-8 upside down and find the battery cover position as in fig C. 1
  3. Remove the battery retaining screw and battery cover.
  4. Check the positions of the main battery socket and switch for the backup battery. (Fig C.2)
  5. Insert the battery lead connector into the socket making sure it fits in the correct way.
  6. Press the center of the connector with an insulated implement, such as a match, to make the connection firm. DO NOT USE an conductive material as this could short the battery.
  7. Set the slide switch to the ON position to connect the backup battery. Again use an insulated instrument to do this.
  8. Install the battery cover and tighten the retaining screw, taking care not to trap the battery leads.
  9. Initialize the PX-8 as outlined in Chapter 2 section 2.1.3

C-5 Replacing the Main Battery

The main battery is expected to have a life of 3-4 years, depending on the type and frequency of use. If the "CHARGE BATTERY" message comes up fre-quently at this time, the main battery needs replacing. Consult your EPSON dealer for a replacement battery. If you are unsure about any part of the fol-lowing procedure, please ask your dealer to change the battery for you.

To change the battery proceed as follows:

  1. SAVE ALL PROGRAMS AND DATA ON TAPE OR DISK. All programs and data in memory, including the RAM disk and Intelligent RAM Disk may be lost when the batteries are changed.
  2. Leave the PX-8 switched on until the "CHARGE BATTERY" message comes up, i.e. the main battery becomes discharged.
  3. Turn the main power switch on the side of the PX-8 to the OFF position.
  4. Open the battery cover. Remove the lead to the main battery, and dispose of the battery in a responsible way. Do not puncture the battery or throw it onto a fire or into water. Do not attempt to take the battery apart.
  5. Do NOT switch the backup battery switch to OFF.


  6. Plug in the lead from the new battery.
  7. Press the reset switch on the left side of the PX-8 while switching the main power switch on. Then release the reset switch. This should be done on replac-ing the battery and not left until it is necessary to use the PX-8.
  8. The supplied battery will only be partially charged and may become com-pletely discharged if it is not charged immediately after replacement. There-fore, charge the battery following the procedure in section C-1, even though the "CHARGE BATTERY" message may not be displayed.