8 February 2018

Amstrad NC 100, Don't Blow a Fuse

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In the last few days I took delivery of an Amstrad NC 100 notepad computer that had been listed on everybodys favourite auction site as not working. The purchase was an educated gamble as all my prior research on the NC 100, along with helpful advice from the Twitter Sphere, pointed to the major cause of failure for these devices being an easy fix. A simple blown fuse that would probably require replacing or circumventing.

After taking the NC 100 apart, locating the fuse where it should be, in the bottom left corner of the main board (power socket facing towards you), I ran a continuity test, the resulting in our prospective blown fuse scenario proving correct.

Amstrad NC 100 Main Board, Left: A Dusty and Blown Fuse. Right: A Temporary Jumper Wire Fix

The non-working Fuse is a  PCB Leaded, 500 mA, 250 V component, which I didn't have to hand. So in order to power up the computer I simply removed the fuse and soldered in a copper jumper wire as a temporary fix. (Next time I place a general component order I'll obtain a new fuse.) This is fine, just as long as I insure the polarity of any power supply is correct, Tip / Outer positive, inner negative.

Interestingly, based on the type of fuse I found in my NC 100 , there seem to be a couple of revisions of the NC 100 board. A number of online references indicate that the fuse should be an SMD component, not a though hole type one. 

A Now Fully Functional Amstrad NC 100

To test, I reconnected the main board to the LCD panel, and screen came to life with a Friendly 'Lithium battery is low' warning, not unexpected as there was no backup battery in the device at the time. Fix completed, and case reassembled, and I'm now the proud owner of a rock bottom priced Amstrad NC 100.

Now to find something for this little notepad computer do, maybe I'll take it to the office and garner some curious and possibly concerning looks at meetings.

Further Viewing

For an entertaining and informative overview of the NC 100, including the replacement of (in this case an SMD) fuse, head over to YouTube and the EEVblog

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