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[Tutorial] Another way to repair your Meade/Celestron red dot sight.

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#1 lRaziel1

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Posted 07 December 2019 - 05:24 AM

First of all, i apologize if my english sounds broken at times, it is not my native language so please be comprehensive.

 

 

 

So, it's not new that these cheap red dot viewfinders fail even on the first night out.

 

User @Bootmaker made a brilliant tutorial about how to fix them:

 

https://www.cloudyni...nder/?p=8716718

 

Note on the repair above, if you do not have any way to solder a wire, i'd recommend you to:

 

1. Expose an extra long piece of wire, 4-5 times as long as the normal small tip you would expose were you to solder.

2. With the exposed wire, sand it down with 800 grit sandpaper or higher to remove any coating it may have. Be gentle or you'll break it.

3. Roll the whole wire around the pin where it broke down, make sure it's tight but dont apply much for or you'll break it.

 

Done. That must provide a connection decent enough to not need soldering. In fact you can do this for different electronics, say your expensive headphone's 3.5mm jack broke, no problem, just buy a new 3.5mm plug from an appropriate hardware store and do the wire rolling process again.

 

 

I must say it's the one that inspired me to both repair this cheap sight and to share it with you guys, so someone who may not be able to afford any other viewfinder or just wants a working spare, just in case, can make use of this. 

 

So the reason for this tutorial, is to address an issue that wasn't the case of above's tutorial. And yes, both of these tutorials apply to pretty much any red dot viewfinder since they all usually come with this exact same circuit.

 

Also i apologize for not showing images directly and only showing a link, but the forum says that i'm "... not allowed to use that image extension on this community." so can't help it. Sorry.

 

 

Let's begin.

 

Basically, the problem here is that the red dot finder was working sporadically. It sometimes turned on, sometimes it didn't, sometimes if i turned the knob very hard it worked, and sometimes i gave it a tap with my finger and it worked. While it was on, i never had problems of sporadic on/off states or brightness variation unless i turned the knob, so that led me to believe that there was just a bad connection, so it was likely fixable and easy to do.

 

 

 

1. So heres the Meade red dot sight included in a number of their entry level telescopes. Hell even their mid end has them. Just under the glass viewer we have the ON/OFF knob which includes a little screw in the middle. This is the one we want to take off.

 

https://i.imgur.com/OV47Rty.png

 

https://i.imgur.com/r5d6KdP.png

 

 

 

 

2. So with the knob removed and the small plastic cover under it removed, we have the heart of the sight. Now we just want to take those 2 black screws off to be able to turn around the little ball and access the circuitry we needed.

 

https://i.imgur.com/XJdpfba.png

 

 

 

 

 

3. Now we have a proper view of what we are interested in. The ON/OFF switch is in the ON position.

While OFF, the pale orange pushes back the bridge via that small metallic protuberance.

 

https://i.imgur.com/oyPgTGz.png

 

 

*OFF position shown below. Note the bridge piece being pushed back.

 

https://i.imgur.com/E3mQIai.png

 

 

 

 

4. Now this is where i found my problem. The return spring, here highlighted with a poorly drawn purple line.

 

https://i.imgur.com/R3FEOKT.jpg

 

 

 

 

5. Basically what happened is actually pretty simple. The lower pin of the spring, the one pointing south-east from this perspective, was way too long and it was shorting the connection between the bridge.

 

-Highlighted in purple, you can see the original lenght of the wire.

-Highlited in gray, you can see the current size of the wire after i removed it and cut it to a proper lenght with pliers.

-In the red circle, you can see the point at which the wire sometimes slid and touched what it shouldn't.

 

https://i.imgur.com/JC1mgh8.jpg

 

 

 

 

 

 

6. I won't explain the process of removing the spring at depth because it's quite obvious, just unclip the L shaped end from it's position, pull of VERY carefully and you are done.

Carefully not because it will break, not at all, but because the metalic piece underneath it that acts as a bridge will come lose as the spring was holding it down, and if the spring or that piece fall, well they are very tiny so good luck finding them.

 

Cut the end of the wire to a lenght where it barely lays next to that protuberance, like the gray overlay line on the picture above.

 

 

 

 

7. To install back again put the spring back into the stake, put the tip you just cut into it's position and hold it in place tightly with one finger, now help yourself with anything, maybe a key to make leverage and return the L shaped end to it's socket.

 

 

 

Screw everything back and voilá. If this was your problem, it should be working fine now.

 

 

This community gave me a warm welcome and advice when i first reached for help, so i thought it was time to give some back, i don't have much experience or knowledge in the astronomy field, but everything that i can contribute, i will. Hope in the future this is useful for someone.

Thanks!


Edited by lRaziel1, 07 December 2019 - 05:29 AM.


#2 FLT-Astro

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Posted 07 December 2019 - 07:26 AM

Thanks for the tutorial.  It’s well written and easy to follow.  Currently I use a Celestron red dot instead of my meade 50mm finderscope.  It’s simply faster to line up onto objects in the night sky.  
 

I’ve had similar problems but mine were due to the battery spring bending and not holding a good battery connection. A piece of aluminum foil under the battery cover fixed the problem.


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#3 BGRE

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Posted 07 December 2019 - 08:26 AM

Unless a gas tight contact is formed (as in a properly executed wire wrap) merely winding a wire around a lead or terminal is a recipe for failure in the long term. It doesn't result in a reliable electrical contact.


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#4 lRaziel1

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Posted 07 December 2019 - 06:24 PM

Thanks for the tutorial.  It’s well written and easy to follow.  Currently I use a Celestron red dot instead of my meade 50mm finderscope.  It’s simply faster to line up onto objects in the night sky.  
 

I’ve had similar problems but mine were due to the battery spring bending and not holding a good battery connection. A piece of aluminum foil under the battery cover fixed the problem.

Indeed, i'd rather use red dots. Yeah that was also a very common problem, the battery just not making contact. Now that i remember thsi was the first thing i tried when i was diagnosing this red dot finder, i just forgot to put it in the tutorial, glad you brought that up.

 

 

 

Unless a gas tight contact is formed (as in a properly executed wire wrap) merely winding a wire around a lead or terminal is a recipe for failure in the long term. It doesn't result in a reliable electrical contact.

 

I agree. Its not realiable but it has an advantage. If tied tightly- it works. The thing is that a lot of people simply do not have soldering tools, and the cheapest ones are not far from costing what another one of these generic cheap red dot finders would cost, you may find a working 2nd hand one for lower.

 

So, as long as there is no alternative that works better than just rolling up the wire and also costs $0 to do, then i guess its not such a bad alternative.




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