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[TowerTalk] Or2800DC smoking control box update

Subject: [TowerTalk] Or2800DC smoking control box update
From: Nathaniel Lee <>
Date: Fri, 1 Jun 2012 18:20:01 -0700 (PDT)
List-post: <">>
Hey All.

An update is warranted.

I received a call from the rep at M2 this morning, CA time, and he said that he 
would have the fellow who installed the tower etc come and replace both the 
rotor and control box on Monday. The installer called and confirmed all the 

So, at this point, M2 has stepped up to the plate and has met me half way on 
this problem. So an A for them on the customer service end now. 

For those watching, the system did work for 2 days as expected at the time of 
installation. The volume of smoke was a bit of a surprise the second time 
mostly due to the fact that the fuse did not pop right away as one would 
expect. When I received the control box back from the manufacturer it did have 
the "smell". When initially testing the system on the dining room table, indeed 
everything worked as expected and this was before the tower went up and the 
whole system was tested including the entire length of cable.

Dave, k1ttt, did suggest that short term testing does not always reveal subtle 
problems (I love the bathtub curve description). Working as a tech myself, in 
the 80's fixing video equipment at a store level, repairs did not always appear 
as complete as the few minutes after would reveal. There were many times we 
would have to watch something for a while (many many minutes) before an anomaly 
appeared. We could never call the customer crazy no matter what the tech said, 
hence the extra diligence. Anything out of the ordinary would have warranted a 
house call. 

My conclusions are similar to what M2 suggests, there must something amiss on 
the tower end. Monday, I will do a quick exploratory for the obvious when the 
rotor returns to earth. They did ask me to measure the resistance across the 
windings and was expected is what was found. I do wish that the manual was more 
detailed as to what to expect in terms of a resistance/voltage chart for ALL 
the terminals.

So that others, less learned, the masses which include myself, I put forth the 
thoughts of others in this group: Many folks have suggested that a single 
strand bridging contacts could cause this problem. The design of the terminal 
strip inside the connection box makes this difficult and as mentioned prior, I 
gave extra due diligence for these connections given how inaccessible they 
would be on the top of the tower and again remind everyone that the system DID 
work properly for two days. There was no problem with the cabling getting 
caught by the turning of the antenna by the tower, no mechanical interference.

Others have suggested that vermin or other animals may have chewed the cable. I 
did verify that the bottom length of cable laying across the ground awaiting 
proper burial is completely intact. the upper 100' I cannot, but do not expect 
much in this regard there. 

Additional emails from others and concerns from M2 suggested that the house 
wiring was awry. I took a DVM and measured the voltage across all the contacts 
on the power cable to the control box. There was ground, hot (119v) and 
neutral. I went to the orange big box store and bought one of those LED plug in 
units that tell you what is at the outlet. It states that everything is normal. 
I compared these results to other circuits in the house and found 
similar/normal results. 

The tower is grounded to the house ground and when disconnected, there is 
approximately half an ohm difference. 

Other people have suggested that I try to rotate the antenna off of 12v just to 
see what happens. I may, but not really worried if the manufacturer is willing 
to swap out both ends.

I will let everyone in on what is found on Monday.  

Thank you all for your valued input. Life hopefully should not be so complex. 


Nat Lee

Somersworth, NH

--- On Fri, 6/1/12, K1TTT <K1TTT@ARRL.NET> wrote:

Subject: Re: [TowerTalk] Or2800DC smoking control box
Date: Friday, June 1, 2012, 11:27 AM

Not necessarily... the bathtub curve applies, it is much more likely for
brand new electronics to fail than those that have been run for years.  If
the factory didn't give it a burn in period it could be a spontaneous part
failure.  Or it could be miswiring internally that didn't show up in
whatever short test they may have given it.  A diode failure in a bridge
could put AC on the regulator, or a capacitor that isn't soldered properly
could be passing half wave dc and over stressing it, connect the wrong wires
to or from the transformer to the board and you could blow lots of things
after a short time, etc.

David Robbins K1TTT
AR-Cluster node: 145.69MHz or telnet://

-----Original Message-----
From: David Jordan [] 
Sent: Friday, June 01, 2012 14:14
Subject: Re: [TowerTalk] Or2800DC smoking control box

Nat sent me a picture of the inside of the controller.  It appears one of
the DC voltage components near the rear panel is fried, maybe a regulator. 
Black soot on the board and melted plastic sprayed on the inside of the rear
panel.  The question in my mind is what externally could be faulted such
that this device would self-distruct with such violence. Having just come
for the M2 factory one would conclude the fault was external to the

----- Original Message -----
From: "Zivney, Terry" <>
To: <>
Sent: Friday, June 01, 2012 9:36 AM
Subject: Re: [TowerTalk] Or2800DC smoking control box

> Les, W2LK said:
> The OR2800DC runs on 30-47VDC. Polarity determines rotation direction
> and voltage determines speed.
> If the control box is smoking, there is probably a stray wire strand
> shorted in the control cable somewhere.
> I would think that the likelihood of a short in the rotator itself is low.
> Pins 1 & 2 on the rear of the controller are the turning voltage.
> Pins 5 & 6 are around 10V, low current, used for the pulse counter and
> shouldn't be a problem.
> Recheck the controller cable connections for stray strands or cracks/cuts.
> Les W2LK
> **************
> A DC motor should turn (slowly) on well under the rated operating
> voltage.
> A short in the 'control wire' will not cause smoking.  The reed switch
> in the rotor SHORTS terminals 5 & 6 in normal operation; shorting
> and opening those terminals is how the control box determines
> the location of the antenna (counting pulses).
> Terry N4TZ
> _______________________________________________
> _______________________________________________
> TowerTalk mailing list


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