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Re: [TowerTalk] Or2800DC smoking control box

Subject: Re: [TowerTalk] Or2800DC smoking control box
From: W0MU Mike Fatchett <>
Date: Thu, 31 May 2012 18:25:37 -0600
List-post: <">>
Have you checked each control wire to ground?  Did you turn it on 
without any cables attached first?  What smoked.  That would be a good 
indicator of what might be going on.

Since you haven't turned the antenna it is hard to imagine that the coax 
loop is pinched or compromised.

I don't know that the connections on that controller are but I would 
look for a rogue wire that is shorting to to another post or pin.

Mike W0MU

W0MU-1 CC Cluster or

On 5/31/2012 6:07 PM, Nathaniel Lee wrote:
> 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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