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Yaesu G-5500 debugging help request



Hello all,

Well, about 2 weeks ago I asked about burned out bulbs in my G-5500 
controller.  Well, I hadn't even had the cover off to look at them, and 
another problem has surfaced.  This is not impressing me since the unit is 
only 1.5 years old and has not been abused.  Use of the rotators hasn't 
even been daily.

In any event, the elevation meter reads 0 deg no matter what position I 
move the rotator to--from 0 to 180 degrees.

Obviously it could be one of the wires to the position pot (it's just a 
variable resistor pot, right?), or the pot has gone bad.

 From what my meter tells me, it seems like contacts/screws numbered 1 and 
2 (on the back of the controller, where the wires run to the rotators) are 
involved.  Seems like contact 1 is the reference voltage (measures 6.12 V 
DC on the EL side, 5.94 V DC on the AZIMUTH side), and contact 2 is the 
feedback/position voltage.

On the AZIMUTH side contact 2 varies from nearly 0V (0 deg) to ~4.35V (360 
deg) ; all looks well.   On the ELEVATION side, it is interesting--while 
the meter doesn't move, contact 2 reads about 0.5 millivolt at 0 deg, 4.0 
millivolts at 45 deg, and 8 millivolts at 90 deg.  So, it's "sort of, kind 
of" working.

Any of you G-5500 repair/debug experts have any advice?

How about instructions for replacing the position indicator resistor 
pot?  Seems like I've seen that on this BB before.

Thanks in advance,

Mark L. Hammond  [N8MH]


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