This is a really odd problem and has happened occasionally for a long time, so it’s not a current version issue nor is it related to PHD or PHD2 or Pinpoint (v6.0.4) as the issue is not about plate solving as such. Using SGP (v126.96.36.19968). The mount is a Skywatcher AZ EQ6 GT using EQMOD.
In the past when this happens I could sort it by either slewing to another place manually and Centering again, or if that did not work, a re-boot of the laptop is needed (Windows 7 64bit). But last night was different and it took many attempts over one and a half hours to get it to centre, and I have no idea why it worked then, but after that I could centre else where as well.
The problem is… The whole plates solve works and it finds it is say 1502 pixels off target (I have it set to get within 12 pixels in 8 attempts, which it normally does within one to three tries). So SGP issues a move and measures again, but the scope is not actually moved, it just thinks it has and then returns near as dammit the same distance off within a couple of pixels, i.e. possibly just the measurement error. It then repeats this till it reaches my limit of 8 and fails. Usually I have aborted long before that as I can see the scope it not being moved. The error remains the same for both RA and DEC. I can physically see the target in the view window well off centre and it stays there, I have also seen it move even further away after a manual slew to the object with Starry Night Pro7.
In the log you will also see some PHD errors, I think those occurred because I had either manually stopped PHD2 or I had at that point closed PHD to see if that helped.
The first SGP log from last night is here:
The problem starts at:
[30/12/2014 18:29:25] [DEBUG] [Telescope Thread] Center telescope message received…
I hope this is enough info, if not just ask. In case you wondering why I have not tried to sort this out before, it’s basically the sky is clear so little, I really don’t want to waste time under a clear sky. But last nights issue has forced me to act.