Epson HX-20

Resources

Wiki
User Manual – EPSON official site
Tips and Tricks – great document with everything you need to know
oldcomputer.info
ganjatron.net
Yet Another Computer Museum – some ROM images inside
Basic Programs
bahamas.gestalter.at – programs

Internals

Motherboard

SW6 microswitch is used to set the language version – please see page 29 of the user manual. DIP switch 4 of that switch must be set to OFF or it will be impossible to enter BASIC.

Memory Expansion

Battery

DSC_0187

The original battery seems to be NiCd 4×1.2V 480mAh. Please see the Tips and Tricks document on the battery replacement recommendation. It is possible to run the machine without any battery, but not with the original power supply, which would provide to high voltage. A regulated external power supply worked well and the voltage range of 5-7V was right to power the computer, however with lower voltage levels it will have troubles operating the printer and tape recorder.

Keyboard

Display

The LCD display module is right above the battery compartment and leaking battery damaged the traces on the board and the connecting tape. There was enough length of the tape to solder the wires to the board – these wires come from an IDE HDD tape. It is possible to solder the wires directly to the tape – the tape will not melt with soldering temperatures up to 350 centigrades.

Tape Recorder

Printer

The non-thermal printing paper ribbons are broadly available today. The ink cartridge is still manufactured by Epson, its symbol is ERC-09.

Reassembly

Advertisements

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google photo

You are commenting using your Google account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s