Amstrad NC100 - No power repair

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rubber_jonnie
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Amstrad NC100 - No power repair

Post by rubber_jonnie » Sun Apr 18, 2021 10:18 am

I recently acquired an Amstrad NC100 and was disappointed to find it wouldn't power on when it first arrived.

As a portable device that runs off 4 AA cells, it's quite interesting for several reasons.
  1. It contains a version of BBC basic, and you can write programs, with a few caveats, that will run on the original BBC machines. This is accessed by pressing Function+B and programs may be saved.
  2. It has a built in serial terminal. This is accessed by pressing Function+S.
  3. It is actually 8 bit as it runs a low power version of the Z80 CPU from the ZX80/81/Spectrum et al.
  4. Expanded to 1MB via PCMCIA cards, it will even run CP/M.
For under £30 the machine I bought was marked spares or repair, and that's always a challenge :)

First off was the keyboard, which had some sticky keys, and that was quickly resolved by dismantling it and cleaning the key stems with soap and water.

Luckily, there is some useful documentation out there for this little machine, so I set out looking for possible causes, and it seems there is a small SMD fuse, .8a, in the positive power rail which commonly fails, so I took that as my first port of call.

Then I hit my next problem. Being in a rental property temporarily I had managed to pack all of my tools away into storage, so not even a multi-meter to start investigating.

So I had to hit up Amazon Prime, and the next day had a cheap multi-meter and soldering iron all for under £20, which shows how easy it is to get started.

Multi-meter in hand I quickly diagnosed that the fuse had indeed blown, and since it is in line with both the batteries and the power adaptor socket, it had to be fixed before going any further.

Here's the back of the mainboard, where the fuse can be found:

MB_Underside.jpg
MB_Underside.jpg (102.42 KiB) Viewed 890 times

And the fuse, marked F301, is up on the left hand side near the backup battery location, removed in the following picture:

Fuse_Gone.jpg
Fuse_Gone.jpg (143.51 KiB) Viewed 890 times

As I had no spare fuse, I had to fit an @exxos approved bodge wire:

Bodge_Wire.jpg
Bodge_Wire.jpg (113.58 KiB) Viewed 890 times

Batteries in, I hooked up the display and got this:

1ST_Power_Up.jpg
1ST_Power_Up.jpg (76.65 KiB) Viewed 890 times

So I grabbed a CR2032, held it in place and powered on again:

2nd_Power_Up.jpg
2nd_Power_Up.jpg (85.25 KiB) Viewed 890 times

A quick bout of reassembly later, I powered on, set the Y2K compliant clock and got this:

Main_Menu.jpg
Main_Menu.jpg (85.11 KiB) Viewed 890 times

Very happy to have this interesting, compact little machine up and running.

:girldance: :girldance: :girldance:
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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Re: Amstrad NC100 - No power repair

Post by PhilC » Sun Apr 18, 2021 10:30 am

Nice easy fix, well done.

I never knew they used to run BBC Basic.
If it ain't broke, test it to Destruction.

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Re: Amstrad NC100 - No power repair

Post by rubber_jonnie » Sun Apr 18, 2021 10:47 am

PhilC wrote:
Sun Apr 18, 2021 10:30 am
Nice easy fix, well done.

I never knew they used to run BBC Basic.
I didn't know about the BBC basic either, but quite a smart move on the part of Amstrad. There are few caveats because of the hardware differences, but a neat trick all the same.

I'm going to try and hook up the serial port and get diag cart outputs from an ST to it.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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Re: Amstrad NC100 - No power repair

Post by PhilC » Sun Apr 18, 2021 11:17 am

There's an nc200 on ebay this morning, slightly tempted.
If it ain't broke, test it to Destruction.

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Re: Amstrad NC100 - No power repair

Post by rubber_jonnie » Sun Apr 18, 2021 11:36 am

PhilC wrote:
Sun Apr 18, 2021 11:17 am
There's an nc200 on ebay this morning, slightly tempted.
Hope it's not the one I'm already watching!
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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PhilC
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Re: Amstrad NC100 - No power repair

Post by PhilC » Sun Apr 18, 2021 11:45 am

@rubber_jonnie probably is as only one on ebay I can see. If you're interested I'll leave it to you.
If it ain't broke, test it to Destruction.

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Re: Amstrad NC100 - No power repair

Post by stephen_usher » Sun Apr 18, 2021 12:44 pm

The Z88 has the same BBC Basic port on-board, but it's difficult to save anything.
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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Re: Amstrad NC100 - No power repair

Post by rubber_jonnie » Sun Apr 18, 2021 3:11 pm

PhilC wrote:
Sun Apr 18, 2021 11:45 am
@rubber_jonnie probably is as only one on ebay I can see. If you're interested I'll leave it to you.
Thanks!!
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

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rubber_jonnie
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Re: Amstrad NC100 - No power repair

Post by rubber_jonnie » Sun Apr 18, 2021 3:13 pm

stephen_usher wrote:
Sun Apr 18, 2021 12:44 pm
The Z88 has the same BBC Basic port on-board, but it's difficult to save anything.
I had intended to go for a Z88, but the prices were daft, not so for the NC 100. I'm quite impressed for an Amstrad product.
Collector of old Atari things:
800XL + Ultimate 1MB, 2x 1010 cassette, 1050 + Happy mod, 65XE (128k +APE Warp) & XC12, SIO2SD, 2600jr, 7800 and Lynx II
Atari 520ST (1Meg), 1040STF long button floppy, 2x 1040 STFMs + Gotek, 2x 4160STE with 32Mhz booster, ROM switcher, Mega ST1, Mega ST4, not to mention various bare ST boards for testing including a PAK 68/2 :)
Plus the rest..
Amiga stuff, Mac stuff, Sinclair stuff etc...
www.electronicnothingness.co.uk

stephen_usher
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Re: Amstrad NC100 - No power repair

Post by stephen_usher » Sun Apr 18, 2021 3:18 pm

rubber_jonnie wrote:
Sun Apr 18, 2021 3:13 pm
stephen_usher wrote:
Sun Apr 18, 2021 12:44 pm
The Z88 has the same BBC Basic port on-board, but it's difficult to save anything.
I had intended to go for a Z88, but the prices were daft, not so for the NC 100. I'm quite impressed for an Amstrad product.
Prices for most things are daft. I was looking through all the retro "spares or repair" listings and many of them are asking for more than a working system or just wacky prices in general. (e.g. £150 for an Apricot monitor and keyboard, no actual machine, and they looked in quite poor condition.)
Intro retro computers since before they were retro...
ZX81->Spectrum->Memotech MTX->Sinclair QL->520STM->BBC Micro->TT030->PCs & Sun Workstations.
Added code to the MiNT kernel (still there the last time I checked) + put together MiNTOS.
Collection now with added Macs, Amigas, Suns and Acorns.

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