Re: Board tester board...

From: Joel Rosenzweig <joel-r_at_an.hp.com>
Date: Tue Mar 03 1998 - 11:26:00 EST

Mitchell Rohde wrote:
>
> > > Try filtering the 10.3V supply some more, first....this sounds
> > > like (no pun intended) noise on the 10.3V supply, which is unregulated,
> > > and goes to both tthe CP and the audio amp.
> > >
> > > Joe
> >
> > I've noticed that different Asteroids boardsets in the same cabinet
> > produce these same beats in sequence with the blinking LEDs on the
> > control panel. I.E, depending on the boardset I've tested, it has
> > either exhibited this phenomenon or not. Strange, no? (Strange yes!)
> >
> > Joel-
> >
> Er... not really that strange. The pulsing is undoubtedly the same
> because they are driven from the same power supply with not enough
> filtering... if you can see the lights all dim and get bright in phase
> with each other, I'd say the problem is pretty bad... :) put some caps on
> that circuit!
>
> Mitch

I think you misread what I wrote. I said that depending on the boardset
that I've tested, I either have or have not had this beating
phenomenon. That indicates that whereas the power supply may share a
large burden of responsibility for the problem, it's not the only
culprit since the PCB was the only variable in the test. My experience
then, is that the beating is very much a potential PCB issue as it is a
power supply issue. I'm not yet convinced it's a power supply problem.
I've used my scope to check all the outputs on the power supply, and
they are very clean DC. Fortunately for me, the set I have in there
right now, does not have this problem, so I'm not all that driven to fix
anything at the moment.

Joel-
Received on Tue Mar 3 08:26:14 1998

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