Author Topic: Weatherproofing control circuits?  (Read 2871 times)

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Offline John Candy

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Weatherproofing control circuits?
« on: September 10, 2009, 07:52:18 AM »
My R/C battery-powered LNER (GC) N5 is back on the workbench, more than 2-years since I last touched it!

Apart from a problem getting the tank/cab unit to fit properly (result of the familiar lack of precision in GRS kits) I need to complete the control circuits.

The R/C receiver is protected from the weather by being mounted in the the back of the cab and and concealed behind the bunker front plate detail casting.

The batteries (12 AA Ni-MH in a 4x3 pack in shrink-wrap) stand on their -ve ends in the bunker, wired into a co-ax charging socket concealed socket behind the buffer beam and with a two-way switch mounted in the cab on the bunker casting.

The Mac5 is to sit on a brass plate which acts as a heat-sink and provides an air gap between it and the steel bunker base. The overload cutout is between the mainframes below the bunker and the whole thing is a very tight fit!

Have not yet fixed the Mac5 to its mounting : Brian Jones recommended 'outdoor grade' double-sided tape when I ordered the unit about 3-years ago (he stressed not to use ordinary indoor tape).
Has anyone found it necessary to add additional waterproofing to protect the Mac5 unit from damp and is there a recommended brand of 'outdoor' fixing tape?
One further point, how warm (or hot) is the Mac5 likely to get and is there any possiblilty of it overheating in the confined area of the bunker?

John.
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Offline cabbage

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Re: Weatherproofing control circuits?
« Reply #1 on: September 10, 2009, 01:44:19 PM »
John,

The last Mach 5 board I saw was factory varnished -thus completely weatherproof. The board will not get that hot anyway -the current capacity is not very great so you will not using the sort of motors that I use. Most of my HEXFET modulators deliver 15A continuous and they are never more than "just off cold" to my touch. The coolant fans I normally fit is more for piece of mind to supply cool air to the motor intakes -rather than the circuit board heatsinks.

As to tape -well I always bolt things...

regards

ralph

Offline Moonraker

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Re: Weatherproofing control circuits?
« Reply #2 on: September 11, 2009, 12:07:50 AM »
I used roof repair silicon to mount the RCS controller and the MyLocoSound soundcard in my GRS Pannier in the photo. I haven't used a Mach 5 but the RCS controller gets only very slightly warm. I guess it depends on how the loco is worked and the rating of the controller. My loco draws 5 amps when it is about to stall pulling a long train up an incline. If the controller is rated at 3 amps then prolonged operation in this way will cause it to heat up.

Peter Lucas

Offline John Candy

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Re: Weatherproofing control circuits?
« Reply #3 on: September 11, 2009, 06:53:32 AM »
Ralph,

My Mac5 came with a flimsy transparent plastic wrap (like the type used in supermarket packaging) which is open at the sides and the PCB is not coated in any way. I am not even sure whether one is supposed to remove the plastic since it covers the cooling fins. I have an aerosol of 'RS Conformal Coating' which I have had for more than 20 years and have never used (I have shaken it and it is still liquid but I have not tested the pressure) and was considering removing the plastic wrap and applying the coating.

Regards,
John.
« Last Edit: September 11, 2009, 07:24:19 AM by John Candy »
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Offline John Candy

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Re: Weatherproofing control circuits?
« Reply #4 on: September 11, 2009, 07:06:48 AM »
Peter,

Silicon sealant sounds a much better option than tape and is one I shall use.

A nice tidy job you have made of the pannier. I had been considering the GRS 8750 kit but after my (unhappy) experience assembling the N5 eventually decided against it (not least because I was not sure about packing in all the bits). I may yet use a sound card in the N5 when I have managed to get the tank/cab unit to fit properly and found space (possibly in the boiler) for a few additional batteries.

What was your experience with the pannier kit?
My N5 was dreadful : Chassis parts incorrectly drilled, bearings and axleboxes/hornblocks which needed filing and reaming to fit both frames and axles, frames and pony truck required a lot  of work before they would fit and, to cap it all, the wrong motor/gearbox was in the kit (which was not clear from the inadequate instructions and it took a few days attempting to make it fit before I realised the fact). I have a live steam 2021PT kit still in the box and the N5 experience put me off starting on it.

Regards,
John.
« Last Edit: September 11, 2009, 07:26:39 AM by John Candy »
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Offline cabbage

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Re: Weatherproofing control circuits?
« Reply #5 on: September 11, 2009, 07:49:27 AM »
John,

The "shrink wrap" is perfectly adequate for the job for which it is intended. If you really want to bullet proof the board then remove the shrink wrap and paint the underside with clear nail varnish. Other than that just stick it to the loco -it seems fine to me.

regards

ralph

Offline Moonraker

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Re: Weatherproofing control circuits?
« Reply #6 on: September 12, 2009, 11:34:23 AM »
John,

My Pannier kit was pretty good with no errors/incorrect components. As is usual for GRS, the instructions were woeful but with a bit of patience I got it all worked out. The biggest problem was figuring out what went where on the backhead. In the end I googled "pannier tank", found a photo of a back head and worked off that.

The RCS radio control is wired to:

     1. Sound the whistle
     2. Open the firedoor ie. switch on an orange light in the firebox
     3. Illuminate the GRS lamps back and front depending on the direction of travel.


Peter
Peter Lucas

Offline John Candy

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Re: Weatherproofing control circuits?
« Reply #7 on: September 14, 2009, 07:09:18 AM »
Thanks Peter.

I may now add the 8750 to my 'to be done' list, particularly since I can now see that all the 'gubbins' can be fitted inside the tank.

John.
My fellow Members, ask not what your Society can do for you, ask what you can do for your Society.