13
Feb
13

Amstrad ALT386 Teardown

Before The teardown

Before The teardown

I have an old Amstrad ALT386 laptop that I got quite some time ago, I use it to do testing of Pascal code for DOS on real hardware as often emulation via Dosbox doesn’t reveal all the bugs. I bought a second machine to use for spare parts as well, so I would hopefully be able to repair faults. It is a 16Mhz 386sx machine with about 4 mega bytes of RAM, it is pretty big for a laptop and was one of the earlier machines designed this way. Unfortunately the machine has stopped working, it powers on but no other signs of life were detectable so I decided to take it apart to see what might be wrong with it.

I had previously had troubles with the video card so I inspected that and tried a few things, but that didn’t work. So I dismantled most of the machine to inspect the main board, riser card and ROM/RAM board. None of these appear to be the problem so I’m still a little bit puzzled as to what might be causing the fault. The machine has a rechargeable Ni-cad for it’s CMOS settings and real time clock, so I suspect that could be an issue. I haven’t had time to test this yet. I may have to remove the battery and fit an alternative cell which shouldn’t be too hard as it is a 3.6V battery pack.

Read more to see some photos of the insides of the machine.

Initial disassembly

Initial disassembly

Closeup of Video Board

Closeup of Video Board

Memory and drives

Memory and drives

The PSU

The PSU

Inspecting the Main board

Inspecting the Main board

Testing before re-assembly

Testing before re-assembly

I still have some further tests, and a few more things I can try, but I don’t think I’ll be able to repair this unit. It’s a bit of a shame as it was the oldest functioning PC I had, and closest in specification to the original DOS machine I had as a kid.

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6 Responses to “Amstrad ALT386 Teardown”


  1. February 16, 2013 at 3:13 am

    Any sign of leaked or scrorched capacitors? Often the first things to go…
    The other obvious possibility is that the PSU has reached that age where it can supply some (slight) power, but not at sufficient voltage. It might be worth checking the levels of the PSU output?

  2. February 16, 2013 at 11:11 am

    Yeah that was my first thought as well, but this machine doesn’t really have many caps on board and they all look physically fine. I need to get a decent mulitmeter to really test the PSU properly, I’ve only got a cheapy thats not really accurate enough. I also want to get an ESR meter to test the power supply caps properly.

    I’ve cleaned and inspected it from head to toe, and I’m not sure what else could be causing the problem, all the spares I substituted didn’t seem to have any effect. At least the hard disk still appears to be spinning up which is a bonus. This may be an excuse to finally buy that oscilloscope I’ve wanted for a while!

  3. 3 rjubber
    March 4, 2017 at 10:46 pm

    I picked up one of these recently – and was lucky enough to get it working. The hardest bit was getting the hard disk to boot dos – it had been wiped and the floppy drive was so knackered it would only read SD disks (and the first 400K, nothing beyond that)

    You mentioned that changing the battery should be simple – do you have any advice about that? I can’t find a direct replacement on ebay, but you seem to be implying that some kind of universal ni-cad replacement would work

    • March 5, 2017 at 1:08 am

      Replacing the battery with a modern Ni-cad should be fairly straight forward. Mostly you need to make sure you get the right voltage cell. It need not be in the same form factor as long as you can fit it in the chassis. Running some wires to somewhere with more room and away from vital components isn’t a bad idea. Hot glue is a nice way to fix one in place.

      It would be good if it was the same capacity, but that more or less isn’t a huge problem if the voltage is right. I remember seeing some Ni-cads that matched this description on my local electronics suppliers website at the time.

      Once you’ve got a similar battery you just have to install it ensuring correct polarity. I’d recommend cutting the old batteries leads leaving some length in the board so you can solder to them rather than risk damaging the main board. Think about wrapping the new battery in something to protect the machine from battery leakage (and to prevent short circuits), preferably something that won’t perish.

      Failing that, you can always replace the battery with a suitably rated super capacitor. It wouldn’t last anywhere near as long, so you’d have to run setup more often, but would have less risk of leaking. I can’t be sure how well that would work though as I’ve never tried it.

      It’s a nice find if you got a working one, replacing the floppy drive might be fun as I think (from memory) it uses a different cabling arrangement to standard PC floppy drives. Check the pin-out for the floppy on-line if you can, perhaps you could make an adapter cable for a standard drive, but that would be a bit harder.

      Cheers
      Sparcie

      • 5 rjubber
        March 5, 2017 at 10:16 am

        Thanks for the all the info! Adapting the floppy drive might prove tricky – although I’m sorely tempted to give it a go at some point. The amstrad has a parallel port on the side, so possibly zip disks could be made to work. Not sure if drivers exist, but it might solve my transfer problems so I could ignore the floppy disk. As for the battery – at some point I may just grab a modern 12V ni-cd battery from ebay and glue it in place. Your advice about extending the contacts is a good idea.

      • March 5, 2017 at 10:17 pm

        I actually assumed you were referring to the Ni-cad on the motherboard for the CMOS settings. Although the same sort of stuff applies to the main battery as well, just you won’t be able to stow a replacement inside the machines chassis and the contacts are a little easier to get to. It might be an idea to fit a connector you can release to remove or replace the new primary Ni-cad battery. If you can you should store the replacement separately to the machine when you’re not using/charging it.

        I’m pretty sure there are Zip drive drivers for DOS it will just depend on the particular drive you have.


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