Opinions on sh101 erratic behavior

[Steve Jones]

On Apr 15, 11:34am, Ken Stone wrote:
 Subject: Re: Opinions on sh101 erratic behavior

> I've never looked at a diagram of the beast, but it sounds like you have a
> power supply problem. Digital stuff will behave quite erratically if not fed
> the correct voltages.  The fault could be the capacitors in the psu, but it
> could also be the regulator semiconductors.  If the capacitors are common
> and you have some to hand, try swapping them out first.
>
> Get a meter onto the outputs of the supply and watch what the voltages do
> during powerup. I suspect they are slowly rising from 0 to 5V? in the
> digital portions of the circuit.

I'm seeing something similar to this on a keyboard I own.
I also suspect something in the PS.  However, I'm a little
nervous about running it long enough to check it out; I'm
afraid I might cook something.  Do you think the effort
would be justified to remove the PS and load it some
other way for testing or am I generally OK leaving it in
the circuit?

Also, when you say 'slowly rising', how slow might slow
be?

-- Don't hate me 'cause I'm beautiful --
Steve Jones
Software and Systems Engineering
ANSYS, Inc.
VOX (412) 514-3067
FAX (412) 514-3114
steve.jones at ansys.com