American Optical 110 microscope switch

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bcjolly
Posts: 31
Joined: Sat Jul 06, 2019 2:50 am

American Optical 110 microscope switch

#1 Post by bcjolly » Thu Aug 04, 2022 10:42 pm

I have 2 AO 110 microscopes. Switch works on both. One powers up on low intensity and will not increase in intensity. The other one powers up at the highest level and will not decrease—hard on bulbs. I am looking for 2(two) switches for my scopes. Any help will be great! Thank you!
BC Jolly

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imkap
Posts: 750
Joined: Thu Nov 25, 2021 9:44 pm

Re: American Optical 110 microscope switch

#2 Post by imkap » Thu Aug 04, 2022 11:13 pm

If I understand correctly you need 2 rotary switch potentiometers. You can buy in an electronics store, just see the resistance value. Probably a local electronic repairman can help you. Cleaning with contact spray might help. Hopefully the switches are the problem

bcjolly
Posts: 31
Joined: Sat Jul 06, 2019 2:50 am

Re: American Optical 110 microscope switch

#3 Post by bcjolly » Fri Aug 05, 2022 12:30 am

You understand right. I have looked at the service manual but it doesn’t give a value for the potentiometer. If I knew the value I would order a replacement. Thank you for your idea about using cleaning fluids. I had not thought of trying that.
BC Jolly

PeteM
Posts: 2986
Joined: Tue Dec 06, 2016 6:22 am
Location: N. California

Re: American Optical 110 microscope switch

#4 Post by PeteM » Fri Aug 05, 2022 12:44 am

It sounds like at least one of the two has the potentiometer windings intact, but the center adjustable connection bad (maybe both, maybe both fixed by cleaning). If so, using a cheap VOM to measure across the outer two solder posts should give the resistance if you need a replacement. Get the old school ones that are designed to handle a bit of current.

Don't recall about the 110, but many of these are a stacked assembly with the potentiometer and a rotary switch stacked one after the other. If so, might be a bit harder to find as a stock item.

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