An Epson QX-10 checks in


A few months ago I managed to get my hands on an Epson QX-10. The slim profile and cool white case had always interested me, especially from a design point of view. It was an interesting example of those CP/M computers out of Japan (and advertised in New Zealand), which never fulfilled their potential in the market place due to the gathering IBM (and compatibles) juggernaut that steamrolled the business market.

Anyway, after taking ownership and cleaning it up I found I had a few issues to solve, namely...

Issue 1: Monitor cord

This is one I knew about. I'd taken ownership of this untested unit without the monitor cord. I was fully expecting to have to make my own but a little web searching lead me to the place that sold new ones!!?? Incredible! Such is the power of the Internet.

Three weeks later I had one.

Issue 2: Power jitters

After connecting everything up and throwing the switch, I was thrilled to see the computer worked. I needed to tweak the vertical hold (I had to break into the case to do this!) but once that was set it seemed to work just fine. Using good old ImageDisk and an Epson QX-10 repository I even managed to make a CP/M boot disk and get other software.

I knew it was too good to last. About 1.5 hours after I'd started using the machine, the power started to flick on and off rapidly. This is not good for the screen or computer of course.

The chief suspect was an intermittent short somewhere? Anyway, to cut a long story short the problem was never diagnosed fully but was finally fixed with a replacement power supply. That is after blowing up two power regulator ICs and destroying a couple of 10 ohm resistors through not running the PSU with enough load! Doh!

QX-10 original PSU

Figure 1. Original PSU. Note the green fan glued on the heat sink


Figure 2. Replacement PSU

Strangely the original PSU had an extra fan fitted? I suspect this was added by a previous owner in an attempt to stop the erratic power fluctuations which they probably suspected was caused by overheating. Alternatively, perhaps the extra fan was drawing too much current and causing the problem in the first place! Who knows?!!


So, I've now got a small software library and the QX-10 is humming along. As a machine it's interesting. It has very slim disk drives, a very sharp mono screen which is capable of fine graphics. It sits low and flat on the desk. The large keyboard feels great.

Epson QX-10

Figure 3. My Epson QX-10

A lovely machine I'm pleased to add to the stash. It now has its own page on the collection site and its own YouTube video!

1st June, 2013

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