My first good find!!!

From: Philip Pemberton <>
Date: Thu Dec 5 02:01:00 2002

Tony Duell wrote:
>> Now, there is a catch. The machine didn't come with a power
>> supply. So, can someone with an Ace, working PSU and a multimeter
>> please tell me what the polarity and voltage of the PSU's output is?
>> I'm hesitant to power up
> I am darn sure it's 9V DC (probably about 1A) and tip +ve.
Well, it certainly seems that way - from the incomplete and poor-quality
schematics I've got, it uses a 7805 1A linear regulator which needs around
8V to 15V to run properly. The usual supply voltage is 9V. IIRC...

> But you can check it for yourself. Open up the Ace (the easiest way
> to do this is to push the centre pins of the 5 fixing studs in, so
> that they fall out inside the cae. Remove the studs and the case top,
> then recover the pins from inside the machine. When reassembing, put
> the top on, fit the studs, and push the pins in from the outside).
Well, that was easy enough, except my Ace only had three fixing studs. I
guess the studs made it a little quicker to assemble an Ace in the factory,
but they're a real pain to remove when the case needs opening...

> The PSU is a conventional 7805-based design (so the 9V 1A input
> should be fine). One side of the input jack socket (I think it's the
> sleeve) goes to the 0V line.
That would seem logical - ring ground, tip power. Same as when a jack plug
is used as an audio connector.

>> the Ace in case I end up fouling up the settings, with fairly
>> predictable results.
> There is nothing totally irreplaceable in the Ace. A ROM dump should
> be available if you need to re-burn the EPROMs. And the other chips
> are standard -- there's no ULA...
In other words, it's a ZX80 workalike that runs FORTH instead of BASIC...

> In any case, most of the time when you get the polarity wrong, the
> 7805 dies, but the rest of the machine survives. Don't try this for
> the fun of it, though ;-)
Strange, I've never killed a 7805 by reversing the polarity. Mainly because
I usually power them up on current-limited power supplies...

I don't suppose you have a copy of the Jupiter Ace schematics, do you?

Received on Thu Dec 05 2002 - 02:01:00 GMT

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