Alt-BEAM Archive
Message #05260
To: beam@sgiblab.sgi.com
From: SG Sparkyg@seark.net
Date: Sun, 11 Jul 1999 23:41:23 -0400
Subject: [alt-beam] power loss>>advice needed
I need y'alls help with a problem that has been bugging me for about 3
weeks now.
the rear servo on my walker has considerably less power than the front one.
but (get this) only when the battery is fully charged.
When the battery is about 10 min from running out the servos werk perfectly
and the walking is grand to watch.
I have:
>>rebuilt the rear H-bridge 4 times (replaceing the 123AP "replacment"
transistors with actual 2N3904's)
>>resoldered the IC connections
>>replaced the IC
>>replaced the Servo
>>replaced the the .22 Caps
>>kicked the cat in frustration
I just don't understand why the thing werks great when the battery runs
down from peak charge.
The battery is a 4.8V (both schematic & servo manufacturer call for 4.8V)
I have two and have alternated them with no change in results. They are
Radio Shack Ni-Cd 4.8V 600mAh
I really don't know what else to do.
NOTE: i tried disconnecting the LED's connected to rear servo thinking this
might be the sorce of a short or something. the rear servo then had about
2X as much power than the front servo (instead of 1/2 the power). This
really messed up the walking gait and the walker just kinda shook and never
worked itself into walking. (even triggered reverser cap somehow a few
times without activating reverser switch) I figured all this must have
happened because the Front servo still had it's LED's connected therfore
making an unequal power draw.
Please... any advise would be great!
Thanx!
-Sparky
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