Help with replacement Hall effect sensors for Orion IntelliScope system

[Rod Brown]

A couple days ago I received an Orion XT8 IntelliScope that was donated to our club. It had been stored outside under a cover for years. The cover kept the tube and the upper part of the particle board Dob mount dry, but the base, including the azimuth encoder, was filled with debris. I cleaned and disassembled it and found that the two surface mount Hall effect sensors had detached from the PCB and stuck to the encoder wheel. I got them off, put a fresh 9V battery in the hand controller, and tested the rest of the electronics, which worked fine. So if I could get a functional azimuth encoder, I should be able to get it all going again.

Could any of you who are more knowledgeable about electronics than I am recommend a suitable replacement Hall effect sensor? The original surface mount ones are labeled "21E". I'd like to find replacements with leads that I can solder to, as some of the pads on the PCB are gone and traces are broken, so I will have to add jumpers.

Thanks,

Rod

[Tony Hurtado]

Rod,

A little more info would certainly go a long way - like a description of the circuit this board is connected to. But hall sensors are pretty simple. Have a look at this one. Same package and the board looks easy enough to repair.

-Tony

On Dec 7, 2025, at 8:13 AM, Rod Brown <rodney....@gmail.com> wrote:

A couple days ago I received an Orion XT8 IntelliScope that was donated to our club. It had been stored outside under a cover for years. The cover kept the tube and the upper part of the particle board Dob mount dry, but the base, including the azimuth encoder, was filled with debris. I cleaned and disassembled it and found that the two surface mount Hall effect sensors had detached from the PCB and stuck to the encoder wheel. I got them off, put a fresh 9V battery in the hand controller, and tested the rest of the electronics, which worked fine. So if I could get a functional azimuth encoder, I should be able to get it all going again.

Could any of you who are more knowledgeable about electronics than I am recommend a suitable replacement Hall effect sensor? The original surface mount ones are labeled "21E". I'd like to find replacements with leads that I can solder to, as some of the pads on the PCB are gone and traces are broken, so I will have to add jumpers.

Thanks,

Rod

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[Joe Acosta]

Those 2 parts are not supposed to be attached for azimuth.  They are separate parts.  I think there is a 3rd part that looks like a sort of T shaped brass tube that connects the 2 together. 

The altitude sensor is 1 part, but for some reason the azimuth is not. 

You can see here that they are 2 separate parts https://www.highpointscientific.com/orion-xt-6-8-10-12-object-locator. 

In some of the Facebook groups and cloudynights.com I hear people have good success with Astrohopper.  https://artyom-beilis.github.io/astrohopper.html

I converted my IntelliScope to a goto dobsonian with a custom mount and onstep. 

Joe 

[Tony Hurtado - Comcast]

Here's another option - super cheap (10 pcs for ~$6) so you can try the repair. You really want to keep the same package for these devices so as to maintain the physical proximity to the magnetic disk. This fits that requirement.

AliExpress: $1.06 | 20Pcs/10pcs 44E 49E Hall Effect Sensor SS49E

https://a.aliexpress.com/_mqlbHPb

My AliEpress orders typically arrive in less than 10 days.

-Tony

On Dec 7, 2025, at 11:41 AM, Joe Acosta <furryj...@gmail.com> wrote:

Those 2 parts are not supposed to be attached for azimuth.  They are separate parts.  I think there is a 3rd part that looks like a sort of T shaped brass tube that connects the 2 together. 

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[Joe Acosta]

Doh, misunderstood. Your missing the actual tiny sensors. Those are tiny solder parts, I think surface mount 🤔

Joe 

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[Rod Brown]

Thanks for the help, Tony and Joe. Tony, I will order the ones that you suggested. 

Rod

On Dec 7, 2025, at 1:04 PM, 'Tony Hurtado - Comcast' via The Astronomy Connection (TAC) <sf-ba...@googlegroups.com> wrote:

Here's another option - super cheap (10 pcs for ~$6) so you can try the repair. You really want to keep the same package for these devices so as to maintain the physical proximity to the magnetic disk. This fits that requirement.

You received this message because you are subscribed to a topic in the Google Groups "The Astronomy Connection (TAC)" group.
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