Re: AP Mother board heating up

Roland Christen

Remove the cover plate from the front of the CP controller and look inside. Make sure that the power transistors are attached to the side of the box via the Phillips screws that attach their tabs. The aluminum box is the heatsink for these power devices, but if for some reason the screw got loose (high vibration could loosen them) the transistors would get warmer than usual. They will not fail in any way since they have internal thermal overload protection, so don't get all worried. But it might explain extra heat if it is not due to hard mesh on the worm (which I suspect was the actual problem).

Normally the CP controller box will get warm when running at the sidereal rate. You can check the current draw from the 12 volt power source with a cheap and cheerful line ammeter, available at most electronic stores. Normal current draw is around 1/3 to 1/2 amp when it is just tracking, may go to 1.5 amps with both axes slewing.


-----Original Message-----
From: Suresh Mohan Neelmegh drsureshmohan@... [ap-gto]
To: ap-gto
Sent: Tue, Feb 14, 2017 4:02 pm
Subject: Re: [ap-gto] Re: AP Mother board heating up

Thanks Joe ,
     Will keep an eye 

On 15-Feb-2017, at 12:56 AM, 'Joseph Zeglinski' J.Zeglinski@... [ap-gto] <ap-gto@...> wrote:

    Hope you find the cause of any “OVER” heating, but there is a positive benefit from some slight heating inside its case, such as you found in the motherboard’s idle mode. When you had to operate the mount controller at your recent high altitude site, at night and –20C, at least the quiescent heating kept the internal electronics operating in their normal room temperature state. Other electronics might have shut down in such cold.
    Don’t recall if there is any provision to completely idle the (DEC) servo motor, but I assume it keeps itself warm by just its motor coils doing “station-keeping”. Of course, the RA servo is always tracking so it shouldn’t get sluggish even in very extreme cold.
    I assume the gear lubricants are in good condition. Perhaps a short blast of a suitable dry silicone spray directly on the worm and its worm wheel might indicate some improvement in tests. Even the AeroSHELL-33 oil “separates out”  from its binding with the lube grease component,  after aging 4 years – the warranty period for that product fresh grease. Not likely the cause here, but your operating or storage environmental conditions may have pushed the limits. However this is stretch, as this is “aircraft lube”, is designed for flying in high altitude cold and desert heat.

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