Jump to content

Loose mirror ASA 12N


Recommended Posts

Hi,

 

I have a ASA 12N I have trouble collimating. The problem seems to be that the mirror can move sideways  about 1 mm. 

When I moved the OTA from vertical +/- 45 degree a "cluts" sound appeared like something was loose. I removed the back cover and found out that I could move the mirror sideways a bit, like the mirror cell diameter is a bit to large for the mirror size, this movement make my collimation change. Has anyone notised this?

I asume this is not normal, is there something I can do or should I Contact ASA? 

I tryed to attached some foam (blue Arrows), se image, to keep the mirror from moving sideways, but that is not a permament solution. I have notised that the 12N OTA have the mirror not glued to the cell.

 

Best regards,

//Christer

mirror.PNG

Link to comment
Share on other sites

Hi

 

At least in case of the 10N the mirror is hold in place by 3 lateral screws (white PE screws) that are only accessible/visible when you remove the mirror cell. This might be different with the 12N but i think that there is a similar way of holding the mirror. 

 

I recently removed the mirror cell of my ASA 10N because of bad hysteresis and time flex measurement results and noticed that one of the 3 screws was loose (from transport?). To my comprehension theses screws should just touch the mirror glas but without any tension! The whole procedure to remove the cell, check the screws and put the mirror cell back in place took me about 10 minutes. Eventually you have to collimate again but if you only loosen the traction screws as described in the official ASA collimation manual on the last page you should end up quite close to where you started. In my case, collimation was even better after the procedure than before. Make sure that you put the mirror back into place at the same position as it was (mark position). Keep in mind that the mirror cell with the mirror is quite heavy!

 

I hope this helps!

Dani

Link to comment
Share on other sites

Christer,

 

Like Dani, I can only answer for the 10N - but I did have a case of loose mirror after I had collimated the primary and was too timid tightening the adjusting screws. During transport the screws loosened and the mirror bacame loose and rattled around in the housing! The plastic screws at the side were correctly set.

 

So it is important to check that the pull and push screws ARE tight - obvious, I know, but.....

 

Regards,

Mark

Link to comment
Share on other sites

  • 3 years later...

(I dont't speak English - I use DeepL Translator  :rolleyes: )

 

Hi,

Yesterday afternoon...

 
1/ I understand why my tube makes noise!
The screws are tight, but the mirror moves 2 mm !!!
 

I put foam on it. I collimate.
post-7979-0-83940300-1537777734_thumb.jpg
 
Before, I had eccentricities that evolved from 0.37 to 0.88 from one image to another one!
Tonight the standard deviation of the eccentricity values (PixInsight) decreases significantly : 0.58 -> 0.61.
 
My images are still mediocre (Eccentricity > 0.45), but now they are all weak in the same way :)

 

2/ During the collimation I discover that the secondary mirror is corroded.

(During nights I use QSI Camera, not my Canon Ixus pink  :lol:  )

post-7979-0-32720100-1537779410_thumb.jpg

In Andalusia the climate is dry, and the equipment is stored dry inside the house during the rainy season.
This morning by looking carefully at the picture, the origin of the defect appears.

I needed a night's sleep to understand the error during manufacture!!!!!
And you, how long to understand? :)

post-7979-0-67642500-1537779657_thumb.jpg

 

3/ My next problem is to understand why I could never set the "PID" in RA during slewing. The mount rumbles, then stalls when it passes near the polar axis...

During 50 sames images during a night, the pointing always drifts in RA, and the eccentricity increases with the duration of the photo.
This should require another post…  :wacko: 

 

Hasta luego  :D 

La Cebra de Andalucía
 

 

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...