Re: Debugging Dec failure to move w/1200 CP3

Roland Christen

I did put the DEC cable onto the RA and the motor did not come on.
If you don't plug the RA cable into one of the motor boxes, the CP3 will automatically assume a motor fault. You must plug the RA cable into the Dec motor box to get a valid result.


-----Original Message-----
From: Steven Panish <scpanish@...>
Sent: Fri, Jul 30, 2021 10:29 pm
Subject: Re: [ap-gto] Debugging Dec failure to move w/1200 CP3

Unfortunately the RA branch of the y-cable is too short to make it to the DEC motor connector.  I may be able to pull off the CP3 and get the cable to connect to the DEC motor.  I did put the DEC cable onto the RA and the motor did not come on.  So that would support the idea that there is a fault in the cable or CP3.  

There is no visible corrosion on any of the connector pins.  They do not appear to be gold plated, this is an old mount. I put DeOxIt on the female connector sockets.  Didn't help.  I'll open the CP3 up and see if any corrosion is visible.  Seems unlikely, this is in an observatory, but NH does get humid.

There are no software limits set that would do this.  The problem appeared out of the blue.

Guess I'll order a spare Y cable next week.


On Thu, Jul 29, 2021 at 4:06 PM Jeffc <jeffcrilly@...> wrote:

On Jul 29, 2021, at 12:00 PM, Christopher Erickson <christopher.k.erickson@...> wrote:

Also consider getting a spare motor Y-cable and try that. EVERYONE should have a spare motor Y-cable in their kit. A spare power cord too.

Fwiw.. I also have a spare Y-cable for the 1200.
I broke the original cable once, and fixed it… but after that incident I decided to get a spare just in case. 

And there is an outside chance that a software axis limit setting is involved.

-Christopher Erickson
Observatory engineer
Waikoloa, HI 96738

On Thu, Jul 29, 2021, 11:50 AM Manusfisch via <> wrote:
Wasn’t there a problem with the CP3 where the inside board became loose or had a corroded connection inside the box that might make intermittent problems come up with power to the motor or control to the motor? I don’t have a CP3 just a later model CP4 so I can’t really comment technically I just remember a conversation

TJF Mobile

On Jul 29, 2021, at 08:18, Steven Panish <scpanish@...> wrote:

The CP3 is connected through a serial/usb converter, but the RA still responds to a nudge even when the DEC does not, so the port is still alive.   And the handbox shows the same issue.  I think the fault has to be later in the path than the comm between the PC or handbox and the CP3.  Although I don't know the architecture.  Good thought though.

On Thu, Jul 29, 2021 at 11:09 AM Eric Dreher <ericpdreher@...> wrote:
Some will sleep, removing power from the port when it's considered inactive.

Roland Christen

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