[TowerTalk] Or2800DC smoking control box update

Nathaniel Lee n1bnc at yahoo.com
Fri Jun 1 18:20:01 PDT 2012

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 essentials. 

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 at ARRL.NET> wrote:

Subject: Re: [TowerTalk] Or2800DC smoking control box
To: towertalk at contesting.com
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
e-mail: mailto:k1ttt at arrl.net
web: http://wiki.k1ttt.net
AR-Cluster node: 145.69MHz or telnet://k1ttt.net

-----Original Message-----
From: David Jordan [mailto:wa3gin at comcast.net] 
Sent: Friday, June 01, 2012 14:14
To: towertalk at contesting.com
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" <00tlzivney at bsu.edu>
To: <towertalk at contesting.com>
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
> TowerTalk at contesting.com
> http://lists.contesting.com/mailman/listinfo/towertalk 


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