AP 1200DA Problem


Brian McFarland
 

Hello everybody,

I recently purchased a used 1200DA mount that had the QMD + DSC encoder upgrade, and it has a problem that I'm wondering if anyone out there has experienced. The RA axis is very stiff while under load (and only while under load). When loaded with a scope that weighs about 75 lbs plus balancing counterweights, the RA axis is so stiff it's difficult to find balance, and the motor repeatedly stalls. This stiffness is present even when the worm/motor assembly is removed, so the clutch and worm-to-gear mesh aren't even part of the equation. When unloaded (no scope or weights), it rotates pretty freely, although not completely free-wheeling - there's still a small amount of resistance even with the worm removed. The rotation feels smooth, not rough. The dec axis behave normally.

My first inclination is to suspect a bearing problem, but this doesn't seem like a typical bearing failure mode.

Any insight greatly appreciated!

Brian


Roland Christen
 

May need main shaft bearing replacement. Was this mount left outside by the previous owner?

Roland

-----Original Message-----
From: Brian McFarland <mcfarlandb04@...>
To: main@ap-gto.groups.io
Sent: Fri, Mar 25, 2022 1:30 pm
Subject: [ap-gto] AP 1200DA Problem

Hello everybody,

I recently purchased a used 1200DA mount that had the QMD + DSC encoder upgrade, and it has a problem that I'm wondering if anyone out there has experienced. The RA axis is very stiff while under load (and only while under load). When loaded with a scope that weighs about 75 lbs plus balancing counterweights, the RA axis is so stiff it's difficult to find balance, and the motor repeatedly stalls. This stiffness is present even when the worm/motor assembly is removed, so the clutch and worm-to-gear mesh aren't even part of the equation. When unloaded (no scope or weights), it rotates pretty freely, although not completely free-wheeling - there's still a small amount of resistance even with the worm removed. The rotation feels smooth, not rough. The dec axis behave normally.

My first inclination is to suspect a bearing problem, but this doesn't seem like a typical bearing failure mode.

Any insight greatly appreciated!

Brian

--
Roland Christen
Astro-Physics


Brian McFarland
 

Hi Roland,

No, he said it's been stored in his basement for years. How should I proceed? I suspect it's not something I can do myself.

Thank you Sir!

Brian


Roland Christen
 

Are you thinking if taking it apart and trying to fix it? Taking one of these apart is not for the faint of heart. If you need to send it in for service, you can contact our office and get a return authorization. It will take a bit of work and expense, but we have all the tools and parts to fix anything.

Roland

-----Original Message-----
From: Brian McFarland <mcfarlandb04@...>
To: main@ap-gto.groups.io
Sent: Fri, Mar 25, 2022 3:24 pm
Subject: Re: [ap-gto] AP 1200DA Problem

Hi Roland,

No, he said it's been stored in his basement for years. How should I proceed? I suspect it's not something I can do myself.

Thank you Sir!

Brian

--
Roland Christen
Astro-Physics


Brian McFarland
 

I was considering it, but I think I'll go the safe route and send it in. I'll call in for an RA today. Between this failed 1200DA and my brand new 1600 that's having warranty repair in work, I have no scope to use. :(

Many thanks!

Brian


Roland Christen
 

I'm not aware of a brand new 1600 mount being repaired here. I checked with the shop and they don't have any 1600 mounts for repair. When did you send it in?

Roland

-----Original Message-----
From: Brian McFarland <mcfarlandb04@...>
To: main@ap-gto.groups.io
Sent: Fri, Mar 25, 2022 3:48 pm
Subject: Re: [ap-gto] AP 1200DA Problem

I was considering it, but I think I'll go the safe route and send it in. I'll call in for an RA today. Between this failed 1200DA and my brand new 1600 that's having warranty repair in work, I have no scope to use. :(

Many thanks!

Brian

--
Roland Christen
Astro-Physics


Brian McFarland
 

It's just the GTOCP4 control box - I shipped the box on Thursday and it'll arrive at your shop on Monday. RA number is 5005. Motor stall errors because there's no signal to the RA motor.  Hopefully a simple fix!

Brian


Roland Christen
 

We just received it about 10 minutes ago. It is an easy thing to fix and you will probably get it back in a couple of days.

Roland

-----Original Message-----
From: Brian McFarland <mcfarlandb04@...>
To: main@ap-gto.groups.io
Sent: Fri, Mar 25, 2022 3:58 pm
Subject: Re: [ap-gto] AP 1200DA Problem

It's just the GTOCP4 control box - I shipped the box on Thursday and it'll arrive at your shop on Monday. RA number is 5005. Motor stall errors because there's no signal to the RA motor.  Hopefully a simple fix!

Brian

--
Roland Christen
Astro-Physics


Brian McFarland
 

Outstanding! I'm looking forward to being back in business.

Many thanks for the support, and have a great weekend,

Brian


Luke Dodd
 

Hi Brian

My new AP1600 is due to ship in the next few days. What was the issue with your new AP1600.

regards Luke 





-------- Original message --------
From: Brian McFarland <mcfarlandb04@...>
Date: 26/3/22 6:48 am (GMT+10:00)
To: main@ap-gto.groups.io
Subject: Re: [ap-gto] AP 1200DA Problem

I was considering it, but I think I'll go the safe route and send it in. I'll call in for an RA today. Between this failed 1200DA and my brand new 1600 that's having warranty repair in work, I have no scope to use. :(

Many thanks!

Brian