Re: TED based motherboard

From: Ethan Dicks (
Date: 2007-04-05 00:40:06

On 4/4/07, Anders Carlsson <> wrote:
> I haven't measured any voltages from the EPROM reader, and I don't
> have enough documentation to know how to change the Vcc if it even
> is possible on this model.

It is almost certainly *not* possible to alter Vcc from the EPROM
reader - that's why I suggested checking it first.  If it's a bit on
the low side, it might be worth investigating why it isn't 5.00V on
the dot.  Also, if you were going to alter it, that would be something
you'd have to do external to your existing EPROM reader.  I never
meant to suggest it was a trivial task, just something that might
help.  If it were me doing it, I'd rig up a stacked connector and just
not pass Vcc from the EPROM reader up to the chip - I'd give it 5.00V
to 5.25V, say, from an external adjustable power supply, ignoring what
the EPROM reader provides.  As long as there's a common ground, the
circuit shouldn't care.

It's not a worry-free operation.  It's more of a last-ditch effort.
Fiddling with the power rail could lead to fried hardware, so my
suggestion was "drastic measures", not a requirement to try.

> If the chip itself has a bit error all
> over it, it may be reason enough for the board to crash on boot-up,
> resulting in no display?

That certainly could be reason enough.


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