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Re: Dead G-5400B



Hello Gerald,
My personal experience of the so-called thermal fuse in the G5400;
What happens when any tracking device allows the rotator to drive against
its end stop is that the motor gets very hot and burns out!
If this is what they call a thermal fuse it's a poor joke.
After this happened to my azimuth rotator for the 3rd time I dismantled the
rotator and fitted limit switches.  I still have some drawings of how I did
it.  As well as the mechanical mods the Start Capacitor had to be resited
from the controller to inside the azimuth rotator.  I've never had the
problem with the elevation rotator, just as well as I could not figure out
any way of doing the same mod on this.

Fred Southwell, G6ZRU
Hon. Secretary AMSAT-UK

----- Original Message -----
From: Gerald Schmitt <kk5yy@arrl.net>
To: <amsat-bb@AMSAT.Org>
Sent: 23 January 2000 16:25
Subject: [amsat-bb] Dead G-5400B


>
> Dear Satellite Colleagues,
>
> After the much vaunted Y2K I was forced to abandon my faithful 16 bit
> Wisp. The 32 bit version  ran strangely but benignly until last night.
> This morning I found the computer locked up and my G-5400 driven hard
> into the stops.
> The elevation rotator has been convinced to work but the azimuth
> rotator seems to be dead.
>
> I went up to the roof and pushed the array and I can hear the gear
> train so the plastic motor gear is still intact. My schematic
> indicates a thermal fuse on the ground return of both rotors but the
> parts break down does not list it. Can anyone shed some light on this?
> I don't remember seeing such a part in the rotator I took apart a
> couple of years ago.
>
> I am still diagnosing the failure and have yet to check voltage out of
> the controller but since the elevation rotator works I don'e expect to
> find the problem there.
>
> Obviously I can fix or replace the azimuth rotator but the computer
> problem will discourage unattended operation until I can get to the
> bottom of that.
>
> My computer is an old AST P75 with 16MB of memory running W95revA
> I would prefer not to change the computer as it is RF quiet in the
> shack.
>
> Thanks for any help or suggestions.
>
> 73 Jerry KK5YY
> ----
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>

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