[amsat-bb] Re: Got Yaesu 5400 rotor control box problem

w4upd updwrb at bristor-assoc.com
Sun Jun 14 07:27:46 PDT 2009

This is similar to a problem I had some time ago and it was both bad 
pots. You have two pots to calibrate the meters and two pots for 
computer control. The computer control ones were very sensitive to EMI. 
I replaced both pots and the unit has been fine ever since. I had found 
the one end of the pots were open preventing accurate adjustments. 
Hopefully this is all that is wrong with yours. The pots were fairly 
inexpensive from Yaesu. I took and paralleled a regular 500 pot 
externally (alligator clip wires) to confirm this and found that I was 
able to adjust the unit.


    Reid Bristor, W4UPD

John Price wrote:
> I have hauled out my spare 5400 rotor for field day and found I have a
> problem. The control box is not sending accurate readings to the
> computer. It works fine as far as the rotor and the meter readings. I
> know the problem is in the control box as the one I use for everyday
> operation works fine with this rotor. I have checked the voltages at
> the transformer and they are OK so I am now suspect of one or
> both of the pots that adjust output voltage. I when I connect it to
> just one side of the rotor I can not get it to adjust to 1023 in the
> calibration routine in the software. Connecting it to the other side
> shows the same result. What I do see is a value that bounces around at
> random.
> I guess my question is does this mean that I have two bad pots or is
> there some common connection between the AZ/EL output that would
> exhibit this result. Any ideas would be greatly appreciated.
> Thanks << John
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