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Re: Dead G-5400B

Good afternoon:

The G5400 DOES have a thermal cutout in the AZIMUTH motor.  And, it WILL reset itself after several minutes.  Unfortunately, the elevation motor has NO PROTECTION other than a fuse which won't blow until after the motor and probably power transformer are fried.

I replaced the fuse in the controller with a much lower rated slow-blow.  Still lost another elevation rotor, but saved the transformer.

Paul makes a VERY good point, and I'd suggest that the place for the hardware timer is in the rotor controller,  serially between the external control input and the relays.  A 556 and a couple of diodes .. . .

73, Jim

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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