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Re: Dead G-5400B

The KR-5600 had end of travel limit switches but only on the AZ rotor.  The
EL rotor still had the thermal cutout switch.  I still have one in the
basement that lasted for 9-10 years when I took it down.  I don't know why
all rotors do not have end of travel limit switches.  The Emoto EV800DX
does on both the AZ and EL but it is an expensive unit.  I don't know about
the M2 unit.  I think the KCT DOS driver has a timeout after which things
are turned off, but only if the PC is still up and running.  I don't know
about the Windows drivers.

The KR-5400 (now the G-5400) had thermal cutout switches on both rotors. 
It would seem to me that thermal cutout switches if designed to protect the
motor, would do just that.  The KR-5400 unit had the KR400 and KR500
rotors.  The AZ rotor, KR400, had the two motor windings on terminals 4 &
5.  The common return for both windings was on both terminals 6 & 7.  If
you used terminal 6, then you had the thermal switch in series with it.  IF
you used terminal 7, then you had bypassed the thermal switch and had no
protection at all.  The same thing is true with the EL rotor, KR500. 
Terminal 6 had the protection, and terminal 7 did not.  I don't know if
this is still true with the G5400 rotors or not, but perhaps someone can
verify this.  If this is still true and by some chance terminal 7 was used
instead of terminal 6, then certainly the rotor motor will be damaged.

Paul Williamson wrote:
> At 04:25 PM 1/23/00 +0000, Gerald Schmitt wrote:
> >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.
> This response won't help you Gerald, and for that I apologize. But this gives me a chance for a rant I've been holding back for years.
> The KCT is an unsafe design. It has no failsafe against software upset. If the software turns on a motor, and then crashes, as apparently happened to you, the motors will be stressed and possibly destroyed. Also, a single random port write is enough to turn on the motors, so it's not unlikely for insane software to turn the motors on by accident. These risks are bad enough under DOS where the KCT was designed to work, but they are absolutely foolhardy under Windows. It was only a matter of time before somebody lost a rotor that way.
> Unfortunately, many rotor controller designs share these defects. Either nobody sees this as a problem, or nobody wants to spend the additional few cents it would cost to add a hardware timeout to protect the motors.
> >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?
> Back in the days when this product was the KR-5400 instead of the G-5400 and came from Kenpro instead of Yaesu, there was a higher model (the KR-5600) that included the thermal cutout. Maybe the schematic is shared between the two models.
> I was under the impression that the thermal cutout on the 5600 would reset itself when the rotors cooled down, but I have no first-hand experience with that. Like everybody else, I have the 5400.
> 73  -Paul
> kb5mu@amsat.org
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73, Roy

Internet: w0sl@amsat.org
Home Page: http://home.swbell.net/rdwelch
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