Remove Primary Cell of Sky-Watcher 190mm Maksutov-Newtonian
Folks, I have just noticed I have a spiders web inside the tube of my Sky-Watcher 190mm Maksutov-Newtonian, its basically toward the primary mirror and it shows up when I take an image.. Does anyone have any ideas how to remove the mirror cell?? There are different sets of screws around the tube but a bit unsure which ones to remove.
First of all I need to make the necessary marks around the tube to make sure the cell goes back in the correct position...
Yep, i have removed my rear mirror cell of my MN190 to clean it and to vacuum out the tube. Steps are:
1. Put the scope on a blanket on a flat surface, a table is good, but the tube must be braced so it cannot roll off obviously.
2. Locate at the rear the six black screws that hold the entire mirror carrier assembly in the tube. These screws are the forward set, not the screws that appear in cutouts in the ring.
3. Place a witness mark ( say a piece of arrow shaped masking tape) on the ring, and the tube section - pointing towards each other and aligned, that is your index mark for reassembly alignment. Undo the six carrier holder black screws. Use a properly sized philips head screw driver and do not slip and scratch the tube, you can tape off the tube with masking tape to protect it, but it won't stop much.
4. With the six screws removed, see if you can slide the white rear carrier ring off the tube. It maybe a very tight fit, do not prise it off. You can try twisting it slightly to 'break' it loose. A final method might be to gently tap the edge of the white ring with a non-marring tool, like a paddle pop stick, working your way around with small taps, it should come loose. Make sure you are holding onto it if it suddenly lets go.Warning, if it will not come loose do not force it, it maybe paint bound and you could damage it. There is an option to come in from the front if necessary.
5. With the rear ring/mirror carrier removed you can proceed with cleaning out your tube. I recommend vacuuming around the baffle rings with a small upholstery brush attachment going forward to remove any metal swarf that may be lying in the folds from manufacturing - mine had some. Do not touch the secondary or the rear of the corrector.
6. Hold the mirror holder vertically resting on a towel and clean it with distilled water and a surgical cotton ball, just dab. You can use a very mild detergent in weak concentration but it must be well rinsed. Allow the water drops to run off, and the surface to air dry. You can wick up small drops off the surface using a absorbant paper towel folder to a point. Just touch the droplet and the paper towel will wick it up. Put aside to completely dry. Do not get the carrier wet, just the mirror surface.
7. When dry, reassemble in the reverse order and make sure your alignment marks line up.
8. When complete, check collimation.That is all that is needed.
Of course the front can be removed as well, to clean the secondary and the inside of the corrector, but that is for another time.
Yep, i have removed my rear mirror cell of my MN190 to clean it and to vacuum out the tube. Steps are:
1. Put the scope on a blanket on a flat surface, a table is good, but the tube must be braced so it cannot roll off obviously.
2. Locate at the rear the six black screws that hold the entire mirror carrier assembly in the tube. These screws are the forward set, not the screws that appear in cutouts in the ring.
3. Place a witness mark ( say a piece of arrow shaped masking tape) on the ring, and the tube section - pointing towards each other and aligned, that is your index mark for reassembly alignment. Undo the six carrier holder black screws. Use a properly sized philips head screw driver and do not slip and scratch the tube, you can tape off the tube with masking tape to protect it, but it won't stop much.
4. With the six screws removed, see if you can slide the white rear carrier ring off the tube. It maybe a very tight fit, do not prise it off. You can try twisting it slightly to 'break' it loose. A final method might be to gently tap the edge of the white ring with a non-marring tool, like a paddle pop stick, working your way around with small taps, it should come loose. Make sure you are holding onto it if it suddenly lets go.Warning, if it will not come loose do not force it, it maybe paint bound and you could damage it. There is an option to come in from the front if necessary.
5. With the rear ring/mirror carrier removed you can proceed with cleaning out your tube. I recommend vacuuming around the baffle rings with a small upholstery brush attachment going forward to remove any metal swarf that may be lying in the folds from manufacturing - mine had some. Do not touch the secondary or the rear of the corrector.
6. Hold the mirror holder vertically resting on a towel and clean it with distilled water and a surgical cotton ball, just dab. You can use a very mild detergent in weak concentration but it must be well rinsed. Allow the water drops to run off, and the surface to air dry. You can wick up small drops off the surface using a absorbant paper towel folder to a point. Just touch the droplet and the paper towel will wick it up. Put aside to completely dry. Do not get the carrier wet, just the mirror surface.
7. When dry, reassemble in the reverse order and make sure your alignment marks line up.
8. When complete, check collimation.That is all that is needed.
Of course the front can be removed as well, to clean the secondary and the inside of the corrector, but that is for another time.
Does anyone have any ideas how to remove the mirror cell?? There are different sets of screws around the tube but a bit unsure which ones to remove. 
