Re: [amsat-bb] 5400 Resistance Readings

[Stan <stan@xxxxxxxxxxx>]

Hello Rick, de Stan, WA1ECF

for the Yaesu model G-5400B az/el rotator system.

For the elevation head potentiometer:
between terminal 1 and 3 is the complete winding of the pot, 500 ohms, 
fixed.
The wiper is at terminal #2.

What ever the elevation position is, the sum of the resistance between 
terminals 1 and 2 added to 2 and 3 is 500 ohms
on or about.

If measuring at the control box, the wire resistance is only a few ohms, 
so we are still talking about 500 ohms.

The motor windings are terminal 4-5 is both windings in series, about 7 
ohms as measured at the control box.
Terminal 4 to 6 and 5 to 6 are the same, about 3.5 ohms as measured at 
the control box.
These readings includes the cable resistance.

Keep in mind there is a motor winding thermostat that will trip out when 
the winding heats up due to being locked up.
It will reclose automatically after cooling down.


Richard J. Lawn wrote:

> I continue to be confused in repairing this 5400B EL rotor and I thank 
> all those of you who have been trying to coach me through the repair. 
> It was suggested that I take readings off EL terminals 1,2 & 3. I have 
> the boom tube removed. I took readings at 0 at the control box 
> terminals with power off and came up with the following:
>
> Pins 1-2 0
> Pins 2-3 3.7 ohms
> Pins 1-3 0 ohms 

If these are the elevation pot resistance's, you have big problems.

>
>
> readings at 90 deg according to the control box meter:
>
> Pins 1-2 243 ohms
> Pins 2-3 210.7 ohms
> Pins 1-3 0 ohms 


The first 2 are in the ball park.... pins 1-3 is fubar. first reading is 
1/2 of the pot, second reading is the other 1/2 of the pot.

>
>
> readings at 180 deg.
>
> Pins 1-2 45.7 ohms
> Pins 2-3 0 ohms
> Pins 1-3 0 ohms 


FUBAR ..... you still have a problem.

>
>
>
> Another ham suggested that a good pot will read 0 ohms at 0 deg., 250 
> ohms at 90 deg. and 500 ohms at full rotation to 180 deg.
>
> Another helpful ham reported the following readings from his healthy 
> EL rotor:
>
> 0ƒ
>
> Pins 1-2 237.2 ohms
> Pins 2-3 2.8 ohms
> Pins 1-3 235.7 ohms
>
> 90ƒ
>
> Pins 1-2 184.5 ohms
> Pins 2-3 172.2 ohms
> Pins 1-3 234.1 ohms
>
> 180ƒ
>
> Pins 1-2 24.2 ohms
> Pins 2-3 228.5 ohms
>
> Can anyone tell me what I should be reading from these pins? Am I 
> reading values from the wrong pins? My AZ rotor is working fine so can 
> I compare readings through the same panel meter rotation?
> I wish Yaesu would have been more helpful in the schematic as mine 
> doesn't even show the two stop switches and does not indicate a value 
> for the pot.
>
> Thanks for any additional help.
> Rick W2JAZ
----
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