[1000mp] Solved!... VFO scan-down problem

[Rod Elliott]

Recap of previous posts...

My FT1000MP Field was scanning down band continuously. I've already 
reported that thanks to Pete K4OM I was able to successfully take the 
main tuning knob apart and get at the shuttle jog sensor, a small 10K 
linear pot. I found that setting its slider at one third of the way 
from one end stopped the scanning. Which is the problem, because the 
jog ring centering mechanism positions it at the midpoint of its travel.

I concluded that there was an electrical problem which had the effect 
of shifting the "no scan" voltage point away from the center of the 
pot. I then spent several hours deep in the Technical Supplement 
trying unsuccessfully to find where that pot connects so I could do 
some voltage checks.

*****

Since then...

When I came back to it next day, I found that the "no scan" point on 
the pot had moved! ... almost to where it wouldn't scan with the ring 
centered. That's when the guardian angel of lids whispered in my ear 
"maybe the pot is dirty". So I waggled the slider back and forth half 
a dozen times, and you guessed it... no scanning, even with the pot 
centered. So, I reassembled everything, and it hasn't scanned since.

So it was "electrical", but much less complicated than I feared.

Yes, there are several unanswered questions...
* how did the pot get dirty in the first place?
* why didn't it clean up with moving the jog ring back & forth before 
I took it apart?
* what, if anything, did the spontaneous resets have to do with this?

I have no answers to these. But, if it acts up again I'll pull out 
the sensor pot and replace it with two 4.7K  1% fixed resistors in 
series. Never did use the shuttle jog anyway!

Thanks to all who responded with suggestions. Between you all I don't 
have to send the rig off to Yaesu California for service.

Cheers + 73!

Rod Elliott  VE3UW


So now the Field goes into the closet as a good backup for the new 
FT-2000. Love it!