LX200GPS SMT with runaway DEC slew

[hickeydp]

I just picked up a 12" LX200GPS SMT for a great price. Haven't had a CAT in a long time and missed my old 10" classic.

 

The guy I bought it from couldn't find the hand box when I picked it up so I hooked it up to my laptop and got it going using the autostar suite (ver. 5.5). I also updated the firmware to 4.2g using the Autostar Updater. 

 

I noticed that when I put it through the auto align routine it would go through finding home/north/tilt/tip just fine but when it went looking for a star the DEC axis would take off and keep spinning after the OTA hit the hard stop. Wasn't sure what was going on. So I skipped the align procedure and pointed it at where a star would be if I had been outdoors. In AS suite I sync'd to that star and then asked it to slew to a nearby star. Again the DEC would take off.

 

Some other things I have noticed...

• The scope defaults to terrestrial targets after a power cycle and DEC takes off when I switch it to astronomical targets.
  
• When looking at the Alt/Az readouts, the Az changes as I slew it in RA but the Alt remains at zero when I slew in DEC.
  
• When I released the clutch, the DEC kept spinning, then stopped and the laptop lost connectivity with the scope - LX handbox crashing?
  
• No matter what speed I select or maximum slew value I set, the DEC axis always runs flat out when the RA responds as I would expect when using the direction keys. This is in the defaulting terrestrial targets mode. 
  

 

What I think is happening here is the DEC encoder at the back of the motor is damaged/faulty. I noticed the DEC manual adjustment knob is slightly bent possibly meaning it has taken some degree of an impact. Could this have damaged the encoder? I have checked the cable running from the RA base to the DEC motor and it seems fine.

 

Be very curious to hear your thoughts on this. If I need to replace the DEC motor, how easily can they be sourced?

[Davey-T]

Best join the LX200GPS Yahoo group, lot's of help there.

Dave

Have heard of encoders that just needed cleaning

[hickeydp]

Cheers, Dave , I'll do that. I've also heard theta the encoders are the weak point in these scopes. Currently trying to source spare parts.