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Is this Spectrum dead?

ssmessme
edited November 2012 in Hardware
Hello. First post and all that...

I have an old Spectrum +3 which has sat on a shelf for many years. Yesterday, when I plugged it in for the first time in a decade the disk drive made a loud continuous whirring sound but there was no red LED on the Spectrum itself.

Is it dead beyond repair? It's my own fault, really, I should have looked after it better.

Any advice on things to check most welcome, otherwise it can head to the tip.
Post edited by ssme on

Comments

  • Mark R. JonesMark R. Jones
    edited November 2012
    Don't bin it, most things are fixable
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  • 1024MAK1024MAK
    edited November 2012
    The red LED is fed off the +5V line from the PSU. So if you have a meter check if you have the correct voltages on the output plug (be careful not to short any of the connections).
    Or if you have another PSU, test the Speccy again.

    Mark
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  • ssmessme
    edited November 2012
    I should mention I haven't tried to hook it up to a TV yet, I just wanted to check if it was getting power. It clearly is getting some power to make the drive whirr, but I guess even if I did connect a TV I wouldn't get any output.

    Time to get hold of a multimeter, I guess. What readings should I be getting from each pin?
  • CameramanCameraman
    edited November 2012
    If you have the manual you'll find a pinout of the powerplug in there.
    You should find at least a pin with 5 and a pin with 12volts.

    Oh here's something I found with Google:
    ---u---
    / \
    / +5 -12 \
    | 0 | at the PSU cable
    \ +5 +12 /
    \ +12 /

    Sorry I cannot get the spacing correct on my Iphone...
  • XorAXorA
    edited November 2012
    From memory I think the constantly whirring disk drive normally indicates a failure of the +5v line on the PSU. Drive motor is powered from +12v so you know that is working.

    I know one of my +3 PSUs the 5v blew! Pretty sure that was its symptoms.

    But a multimeter will show this easilly!
  • guesserguesser
    edited November 2012
    Yep, it will have lost its 5v supply. I can be almost certain I know which component in the power supply failed too. It should be an easy repair, the only difficulty is the immense weight of the PSU if you have to send it to someone to get fixed.

    The +3 itself most likely has nothing wrong with it.
    My rubbish website including the redrawn Amstrad schematics and the Sinclair Wiki.
  • ssmessme
    edited November 2012
    guesser wrote: »
    Yep, it will have lost its 5v supply. I can be almost certain I know which component in the power supply failed too. It should be an easy repair, the only difficulty is the immense weight of the PSU if you have to send it to someone to get fixed.

    The +3 itself most likely has nothing wrong with it.

    Thanks for the information. What component do you suspect has gone wrong? I wish I had another supply to test it with!
  • BCHBCH
    edited November 2012
    ssme wrote: »
    Thanks for the information. What component do you suspect has gone wrong? I wish I had another supply to test it with!

    Assuming the 12v are ok (the 5v are generated from the 12v line I belive), there's three components you should check, two transistors (h1061 and 2222A) and the IC ca723c. You'll need a multimeter.

    Here is a diagram of the power supply circuit:
    http://hardware.speccy.org/hardware/Fuente+3/esquemas.html
  • guesserguesser
    edited November 2012
    Most likely T2 ( the 2N2222) and possibly also T1. If T1 has failed you can replace it with a TIP41C
    My rubbish website including the redrawn Amstrad schematics and the Sinclair Wiki.
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