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[TowerTalk] Or2800DC smoking control box

Subject: [TowerTalk] Or2800DC smoking control box
From: Nathaniel Lee <>
Date: Thu, 31 May 2012 17:07:37 -0700 (PDT)
List-post: <">>
Hi All,

I am hoping for some help here with the DC rotor box from M2. The rotor and box 
were installed brand new along with the rest of the installation and worked 
fine at calibration on the dining room table and again for 2 days. After which 
the rotor box smoked. I sent the box to M2 and it returned today and smoked 
again upon wiring it in and I did not even have a chance to spin the antenna 
before the magic smoke appeared. It also still smelled smoky coming out of the 
shipping container.

Before doing so, I checked the wiring from the tower to confirm the motor 
winding was not shorted and indeed, it had a few ohms of winding resistance. 
The cable is not undersized for the distance either 200'. I actually tested the 
rotor cable immediately after discovering the smoked box and it has not varied 
in terms of the measurement of the motor wiring's resistance for the last 3 
weeks being without the box.

The M2 people are suggesting something is wrong at the tower level. Since it 
cost a pretty darn big penny to have it all installed and I need a hip 
replacement soon, I am not running up and down the tower for this. Someone else 
has to go twice in order to retrieve and reinstall. $$! I checked the tower 
ground which is tied into the station ground and upon separating the two, the 
resistance was minimal, on the order of an ohm. 

They suggested checking the house wiring for a missing neutral? Really? Nothing 
else is smoking and the tail-twister in use at another tower performs 
flawlessly and is also tied into the same ground. Everything else is just fine. 
Not even a hot chassis. I am using braid everywhere for inside grounding and it 
goes to two 8' ground rods only about 5' away. 

How do I check for a missing neutral without getting zapped in the process? 
What else can I look for? I am peeved that it worked for 2 days without 
incident because it indicates it was not an installation error. Nothing has had 
a chance to deteriorate. I suppose testing with a light on a 2 prong plug would 
indicate a missing neutral?

Nat Lee

Somersworth, NH

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