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General Category => Amstrad CPC hardware => Topic started by: Munchausen on 17:35, 09 April 14

Title: Another CPC back from the dead
Post by: Munchausen on 17:35, 09 April 14
The replacement RAM chips for my GX4000 arrived today (technically not a CPC I know). 15 minutes later and I'm playing switchblade  :D


It was only the RAM, not even the Z80 failed!
Title: Re: Another CPC back from the dead
Post by: CraigsBar on 18:29, 09 April 14
Nice. Enjoy it.
Title: Re: Another CPC back from the dead
Post by: radu14m on 19:01, 09 April 14
well done !


A stupid question: why the RAM died first ? ( in almost every case )
Is this so sensitive ?
Title: Re: Another CPC back from the dead
Post by: Munchausen on 19:13, 09 April 14
I have no idea.. I guess it is the weakest part (Bryce?)


It's far too easy to plug the wrong voltage in to the GX4000 - it has two sockets, one for 5V the other for 11V, but it isn't marked which is which. I had to dismantle it and compare it to the schematics to figure it out!
Title: Re: Another CPC back from the dead
Post by: gerald on 21:29, 09 April 14
Quote from: Munchausen on 19:13, 09 April 14
It's far too easy to plug the wrong voltage in to the GX4000 - it has two sockets, one for 5V the other for 11V, but it isn't marked which is which. I had to dismantle it and compare it to the schematics to figure it out!
While the connectors are not marked (which is really bad), it is not possible to plug the original 11V power supply in the 5V socket.
The problem comes from 3rd party power supplies with their wide selection of plugs you can choose from. ::)
Title: Re: Another CPC back from the dead
Post by: Bryce on 07:56, 10 April 14
RAM is generally more sensitive than other ICs. Whereas the CPU and Logic chips are just a large collection of resistors and transistors, RAM ICs are huge arrays of tiny capacitors that are very sensitive to voltage spikes and depending on charge (batch) quality can deteriorate over time without any negative external influences.

Bryce.
Title: Re: Another CPC back from the dead
Post by: TFM on 16:57, 10 April 14
Yes, spikes are the problem...


Max Green Protection(TM) Spikes Animation (http://www.youtube.com/watch?v=hl_yR7rZ_xA#)
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