19 Feb
2013
19 Feb
'13
6:19 a.m.
On 02/18/2013 09:27 PM, mc68010 wrote:
Have you disconnected that ribbon cable at any time? I've found an old
email which suggested that - at least with my system - there was a factory
assembly error with that cable, and one of the plugs was put on backwards.
The plugs are keyed, but one end (and I suspect it was the end nearest to
the power switch) had to be forced into its socket backwards for the system
to run.
When I disconnected that cable for some reason (probably to remove the
front panel so I could get at the drives and image them) I naturally put
the cable back "the right way round", and got myself a dead system. After
doing some head-scratching and tracing with a meter I discovered that it
had to be connected backwards for things to work.
Just a thought - I don't know if my system was unique, or if this affected
a small batch of them, or if all Towers are like this.
Does your
system show any signs of life at all? I *think* my system
needed the large internal battery connected (and vaguely-chargeable)
before it would fire up, even though that was supposedly only there as a
memory back-up during power-fail conditions.
The power supply does show some
activity when plugged in. It puts out
+6.75v to the battery and the +5v test point is up. None of the other test
points show anything. There is a switch on the PS for battery backup power
to ram. In the on position the PS fan spins but, I don't see any other test
points coming up. The +5 is getting to the power switch and the switch is
working fine.
The power switch connects by ribbon cable to the back plane. The back plane
is completely covered by a steel plate on the sides and bottom. Without
taking apart the whole machine I can't see where it is actually going. This originally had a bad battery with corroded
terminals. I bought a new
one off ebay but, I never really checked it. It's some no name Chinese
thing. I probably need to see if it is actually fully charging and holding
it. I just plugged it in and checked and it is charging up slowly anyway.
I'll actually check the volts this time but, I left it plugged in about 7
hours before and it still wouldn't start up when I tried. Maybe it's a bum
battery though.
7 hours seems too long; someone familiar with these machines once told me
that with a totally flat battery they sometimes need a half hour or so if
sitting before they'll spring into life.
cheers
Jules