[TowerTalk] US Tower HDX-589MDPL UP/DOWN switch failure

[Patrick Greenlee]

Most likely standard switch assemblies not liquid or vapor tight 
selected on price and put into an outdoor environment.

It is amazing how little critters can foul things up by committing 
suicide on electrical contacts.  I had some relays that strongly 
attracted ants.  Dead ants by the hundreds until finally the contacts 
were fouled.  Replaced with a sealed/enclosed relay.  Had the same 
problem with ants committing suicide on the contacts of a pressure 
switch on a water well. Arranged for them to traverse cloth saturated 
with bug spray  to get to the contacts.  Problem solved as they died 
trying to get to the electrical sacrificial alter.

Patrick   NJ5G

On 7/2/2015 11:08 AM, john at kk9a.com wrote:
> I would definitely do something to ensure that you can turn off your tower
> gear motor.  Changing to a 4 pole switch seems like an easy solution.  I
> would also question why the switch contacts were damaged, are they
> properly rated?
>
> John KK9A
>
>
> To:	"towertalk at contesting.com"
> <towertalk at contesting.com>,	"lists at subich.com" <lists at subich.com>
> Subject:	Re: [TowerTalk] TowerTalk Digest, Vol 151, Issue 6
> From:	K2CB <k2cb at comcast.net>
> Date:	Thu, 2 Jul 2015 11:21:29 -0400
>
>
> Joe,
>
> Good point on the two switches wired in series being an issue once the tower
> reaches one of the limit points. In over thinking things, that fact
> slipped my
> mind.
>
> While the use of a 4PDT switch to include the switching of the hot lead would
> not be a bad idea safety wise, it still would not solve the issue if the
> neutral contacts shorted during actual operation, as in my case. The overall
> switch would still be in the on position while moving the tower.
>
> At least the motor would not buzz when the switch is returned to the off
> position if one set of contacts failed. But then again, that could be a bad
> thing, because then you would not know if there it was a failure with one of
> the other pole's contact set.
>
> I guess the best solution is just to do periodic testing, and hope it does
> not
> fail in the wrong circumstance!
>
> Eric
> K2CB
>
>
>
>
>>> Looking over the wiring diagram for the control box after the fact,
>>> I am questioning why UST did not just simply wire the two limit
>>> switches in series, then just use the UP/DOWN toggle switch to break
>>> the connection between the series-wired limit switches and the motor.
>> With the limit switches in series you would not be able to move the
>> tower off either limit.
>>
>> It would be better to use a 4PDT center off to switch hot/neutral or
>> a using separate switches - one to control direction the other to
>> switch power.  The problem with the two switch version is the need
>> to remember to stop motion before reversing direction.
>>
>> 73,
>>
>>    ... Joe, W4TV
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