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RE: Yaesu G5500 Rotor Woes



Hi Paul,
	When I was in college I worked in a TV shop and we had a trick for finding
shorts in TV's. We'd put a 100 watt light bulb in series with the power to
the shorted
TV. As long as the short existed The light was on but the fuse wouldn't
blow. We
could then disconnect different sections of the TV (with the power
unplugged) until
the light either went dim or out and we were able to isolate the shorted
section.
Steve .. AI7W

-----Original Message-----
From: owner-AMSAT-BB@AMSAT.Org [mailto:owner-AMSAT-BB@AMSAT.Org]On
Behalf Of K5OE@aol.com
Sent: Sunday, August 11, 2002 16:47
To: pwillmott@northrock.bm; amsat-bb@AMSAT.Org
Subject: Re: [amsat-bb] Yaesu G5500 Rotor Woes


Paul,
Here is a common scenario:
1.  The elevation rotor fails (limit switch failure or whatever) and causes
the motor to short out (high temperature melts the insulation on the
windings).
2.  This then draws excessive current (dead short, practically) and the main
transformer in the control box fails.
3.  This then, finally, blows the 10 amp fuse in the control unit.

A good test of the box is to unsolder the 120 Vac leads to the transformer
and then see if the fuse blows.  If not, then disconnect the low-voltage
side of the transformer, reconnect the high voltage side, and test again.  A
blown fuse now indicates the transformer is shot (but the rest of the box is
probably OK).

After you replace the transformer, disconnect the rotor and see if all is
OK.  You will now have to troubleshoot the rotors to find the real, initial
problem.  Reconnect the az rotor first and check.  Next the el rotor.  Good
luck.

73,
Jerry, K5OE
ps:  put a fast-blow 5 Amp fuse in the box :-)




In a message dated Sun, 11 Aug 2002 11:24:48 AM Eastern Standard Time,
pwillmott@northrock.bm writes:

>
>
> Hi Group,
>
> A week ago my virtual new (less than 1 year old), G5500 rotor stopped
> working. In fact the fuse had blown, ... visible inspection of the inside
of
> the controller shows no sign of burning etc, the cable looks fine, and the
> rotors themselves look ok, ... at the time of the fuse blow the rotor
hadn't
> been used for long prolonged use, ... its only used for AO40 and updated
via
> software only once per minute.
>
> Now the problem is that replacing the fuse doesn't help, ... every time a
> new fuse goes in it blows instantly, ... so I guess something has failed
> short. The trouble is that without having the unit powered up its hard to
> find what is wrong.
>
> Has anyone else had this problem, ... or perhaps suggest a test sequence.
>
> Thanks
>
> Paul, VP9MU
>
>
> ----
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