Slow Tracking

[Martin J Smith]

Hi, I've been happily tracking and guiding for over a year with an EQ5 mount. It's controlled via a laptop with and EQDIR adaptor using EQMOD, guiding with PHD and assisted with Cartes du Ciel. One night last week I started getting star trails, the images drift eastward noticeably over a few seconds. PHD can't keep up with the drift, though I don't think it should have to.

I don't think that Polar alignment or leveling are an issue. Using the Synscan handset instead of the adaptor has no effect. I can speed up by switching to custom tracking and using a rate of 16 deg/hr, though the actual amount varies by +/- half a degree or more. I've tried changing the power supply and adjusting the RA worm gear to no effect. Coming to the conclusion it's a fault with the motor (might try switching the RA and DEC motors around) or something electronic in the junction box.

I'd be really grateful if someone could shed some light on this. Thanks in anticipation, happy new year!

Martin

[Dr_Ju_ju]

have you tried swapping\changing the cables from the EQDir to the stepper motors ? it could also be that one of the driver modules in the EQDir has developed a fault..

[Martin J Smith]

Thanks I'll try that first.

[Martin J Smith]

Julian, do you  know if the plugs (in the control unit) can simply be swapped round? RA has 5 pins, DEC 4, presumably the extra (grey one) is power as it goes to the body of the socket. I can't find a wiring diagram as yet...

Thanks.

[Dr_Ju_ju]

The ST4 port is 6 pin (RJ11), and the Syscan handset is 8 pin (RJ45)....

On re-reading your post I think I've got my wires crossed, so this mount is an EQ5 GOTO?, and you normally drive the mount via the handset (using direct PC mode)? or do you plug the EQDirect directly into the mount driver box ? (the best way) 

If trying either, the problem is likely to be in the motor driver box, or the cables from the box to the motors... I don't know what type they are, but on my EQ3 they are 8 PIN DIN connectors...

 

[Martin J Smith]

I plug the eqdirect into the motor control box so no handset. These are the plugs I was taking about.

[Dr_Ju_ju]

that extra grey wire, is an earth connection, so you could just swap them over, but I'd more likely suspect the DIN cables from that socket to the individual motors....

[Martin J Smith]

ok I'll have a look at them too. Can't test until the next clear night though, will let you know what happens. Thanks...

[Martin J Smith]

Bonus clear sky tonight. Changing the leads had no effect so I went ahead and swapped the RA and DEC output plugs. Using a custom tracking rate of RA = 0, DEC = -15.041 resulted in spot on tracking, so it is the RA driver module at fault, just as you suggested Julian.

Now how do I tell EQMOD what I've done so I can point the scope where I want? :-)

Julian thanks for your help, I can get some sleep now.

All the best,

Martin

[Dr_Ju_ju]

Unfortunately, now that you've identified the problem, as the electronics, it would be best to get a replacement driver board from http://www.opticalvision.co.uk/

[Martin J Smith]

All I've managed to find is a new control unit from FLO at £100. Just the motherboard would do. As I've just had an unexpected win on an EQ6 on ebay I want to sell the EQ5, which broke down just after. Typical. I'll probably sell the mount and remaining electronics separately unless someone wanted it as it is. Cheers :-)