HP battery eliminator connectors - found
glen.slick at gmail.com
Sun Feb 25 21:06:49 CST 2007
On 2/25/07, Gordon JC Pearce <gordon at gjcp.net> wrote:
> As someone who has never played with much old HP kit, I find myself
> having to ask:
> What exactly does this plug do?
Here's the basic story. I don't have the exact details without
checking the manuals and schematics.
The power supplies on HP-1000 E/F systems had a battery backup option.
When installed an external battery box would be connected. The power
supply would charge the batteries when AC was present and could run
off the batteries when AC was lost. To make sure the batteries didn't
overheat while being charged there was a thermister in the battery box
which would shut down the power supply when the thermister got too hot
and its R value got too high.
If the power supply has the battery backup option installed but the
battery box and its thermister is not connected the power supply will
not power up all of the way. The eliminator plug simply has the right
R value to make the power supply think the battery box is connected
and not overheated so the power supply powers up all of the way.
I believe the main supply rails all come up ok without the plug and if
you didn't know better you would think the CPU should be working, but
I think the firmware stays stuck in a halted state waiting for a power
good signal, or something like that. If you're new to HP 1000 CPUs
and you hit this you'll waste a lot of time trying to figure it out.
If the battery backup option is installed in the power supply you
cannot easily remove it. A jumper board in the power supply is
replaced with a different board (either an inverter board or charger
board, I believe), and if you remove the battery backup option boards
you won't have a jumper board to put back in place and the supply will
not work without it.
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