Gianmario.Scotti_at_nokia.com
Date: 2004-01-19 00:08:21
> -----Original Message-----
> From: owner-cbm-hackers@cling.gu.se
> [mailto:owner-cbm-hackers@cling.gu.se]On Behalf Of ext Bo Zimmerman
> Sent: 18 January, 2004 21:51
> To: Cbm-Hackers@Cling. Gu. Se
> Subject: My own PS problems..
>
>
> Hello all,
>
> Since there is so much discussion of power supplies, I
> wondered if I might
> mention my own old, long-standing problem with my two C900s.
>
> They come from Europe, of course. As I'm in Texas, I use a
> 110V<->220V
> step-up/step-down transformer that works absolutely fine on
> all my European
> PETs. However, on the C900, I can never seem to get enough
> volts out of it.
>
> I know that's pretty vague, but any pointers on what I might
> look into would
> be appreciated.
>
> It's a switching power supply if that helps -- no big coils
> like the PETs and C64s use to modify voltage.
You just described an AC-AC inverter. It's likely that the
output of this device is not a pure sine. No equipment likes
to be fed with a square wave or a krixkrax sine instead of a
pure sine. I am not saying this killed your C900, but he ain't
liking it, that's for sure.
I am a huge fan of step-up and step-down transformers, because
they create pure sine-waves, as opposed to inverters that
basically construct the wave more or less succesfully. Best case,
you get a krix-krax(tm) waveform, worst case you get a square wave.
Electronic devices don't like that. And check, these heavy and
somewhat expensive step-up/down transformers are still sold today,
(I just looked into the newest Partco catalog - yep, they're there)
so there's a market for them. (And if you ever decide to buy such
transformer, I suggest Todd Systems, good quality and rather cheap,
expecially compared to Europe).
Now, that said, the problem of using a step-up transformer in USA is
that it will give you the same frequency sine wave as the one in the
grid, which is 60Hz. In Europe, however, it's 50Hz, and it's this
signal that, if I understand correctly, is used to generate some
video timings in some (all?) commodores.
Let me now just take a step back and look at all these issues: I am
guessing that you might not actually have an issue with the voltage
that's output from your inverter, but rather
a) it's waveform or
b) it's frequency.
Why frequency, you might ask. After all, inverters are supposed to
construct a wave of the correct frequency. Well, yes, and no. The
problem is that I imagine inverters creating all sorts of frequencies
between 50 and 60 Hz. You might want to check with an oscilloscope
what yours is doing.
Well, I don't know if you know if you have a scope, but maybe you can
ask a friend that has one. I'd do this gladly for you, but I understand
that the distance between us would present a challenge.
cheers
mario
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