Re: Ramworks III

["Michael J. Mahon" <mjmahon@aol.com>]

fixme1@gmail.com wrote:
> Hi, I have a Ramworks III card in my platinum IIe and its making a high
> pitched whining noise, especially when I run the XPS Diagnostics IIe
> disk.  Apple Works is only showing that I have 56k available memory
> too.  The card is populated which equates to 1 meg of ram combined.
> 64k on the motherboard and the rest is on the Ramworks III card.  Could
> the whining noise be attributed to a failing chip or failing board?  I
> hope this is not the case.  Any help would be greatly appreciated.
> Thanks

It's not the RAMworks board making the noise--there's nothing on
the card that is capable of making a noise.

It's the adjacent power supply making the noise, or possibly noise
on the +5 power bus making itself audible through the speaker.

The power supply is a switching type, which normally operates
at an ultrasonic frequency (though different supplies may differ
in operating frequency), but apparently yours is exciting vibration
at a subharmonic, probably in the core of the toroidal transformer.

If your machine is otherwise operating normally, power supply noise
is essentially a mechanical problem relating to the windings and
mounting of the toroidal transformer.

If the *frequency* of the whine is changing, then either the power
supply is operating in an unstable mode or it's some other oscillation,
perhaps in the speaker circuit.

-michael

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