Alps rotary encoder ID help - Page 1
Forum section: electronics / repair

author: sudont
author_rank: Newbie
timestamp: September 08, 2020, 06:36:41 pm
content: I've searched online for info and still no idea what kind of encoder this is.It's labeled Alps 811c / 631c, and it's from the late 80sI'm trying to find a replacement, but am stumped.Any help would be greatly appreciated

author: sudont
author_rank: Newbie
timestamp: September 09, 2020, 09:30:11 am
content: My guess was that it's mechanical and presumably capacitive?, but I've found no such thing exists on digikey.

author: mikerj
author_rank: Super Contributor
timestamp: September 09, 2020, 10:05:28 am
content: If it's a normal mechanical contact style encoder there should be plenty of choice for modern replacements, especially as it's wired rather than PCB mounted. How many pulses per revolution does it have?

author: sudont
author_rank: Newbie
timestamp: September 09, 2020, 10:50:01 am
content: I counted around 48-50, and tried googling for said and nothing came up.Any further help would be greatly appreciated, thanks

author: madires
author_rank: Super Contributor
timestamp: September 09, 2020, 11:22:53 am
content: Detents? If yes, how many?

author: Ario
author_rank: Regular Contributor
timestamp: September 09, 2020, 02:38:10 pm
content: I would try googling the product it came out of?

author: free_electron
author_rank: Super Contributor
timestamp: September 09, 2020, 04:05:25 pm
content: custom job. Alps does many of those. almost all the combo potentiometers / encoder in car radios are Alps custom jobbo's

author: Audiorepair
author_rank: Frequent Contributor
timestamp: September 09, 2020, 07:10:03 pm
content: Buy a bog standard rotary encoder, they all work the same and are really cheap.http://www.farnell.com/datasheets/1837002.pdf?_ga=2.91571290.1764911387.1599678160-1771980843.1483642398&_gac=1.82231012.1599244606.Cj0KCQjwy8f6BRC7ARIsAPIXOjiAduvn9NAj5Ik0rGDp3u43Ww4Q0rjFBeeDwYnXOKyW2GQUczDMzwMaAo9aEALw_wcBIf you establish that this works as expected bodged into your circuit, then you just need to find a modern one that will fit and looks the part.(If it works backwards, you just need to swap 2 pin connections over)

author: mikerj
author_rank: Super Contributor
timestamp: September 10, 2020, 07:44:15 pm
content: Quote from: sudont on September 09, 2020, 10:50:01 amThat is quite high for a contact based encoder, I can see why you are struggling to find anything. Does the pulses per revolution actually matter e.g. is there a scale on a panel that the knob aligns with?Grayhillmake a 36PPR encoder with detents.

author: sudont
author_rank: Newbie
timestamp: September 14, 2020, 11:33:18 pm
content: Quote from: madires on September 09, 2020, 11:22:53 amYes it has detents, via a ballbearing, I'll count them tomorrow and get back to you, thanks.

author: sudont
author_rank: Newbie
timestamp: September 14, 2020, 11:46:25 pm
content: Quote from: Ario on September 09, 2020, 02:38:10 pmI tried, but it's a rare piece of gear, can't even get the service manual on it.Quote from: Audiorepair on September 09, 2020, 07:10:03 pmThank's for the help, I'll check the datasheet tomorrow to see, I already have a bog standard rotary encoder I can try with it, it's just the switch mode PSU is failing and needs recapping before doing more testing.

author: sudont
author_rank: Newbie
timestamp: September 15, 2020, 10:53:51 am
content: It has exactly 50 detents, which I'm guessing should match the pulses per revolution?

author: madires
author_rank: Super Contributor
timestamp: September 15, 2020, 12:09:36 pm
content: Earlier you've mentioned that you've counted about 50 pulses per revolution. Was that just for the A (or B) pin or for both? 50 pulses on one pin would mean two Gray code steps per detent. In that case you could try an encoder from the ALPS EC11 series (one with 30 detents).

author: sudont
author_rank: Newbie
timestamp: September 15, 2020, 12:16:55 pm
content: A, and b pins are mirrored, so it's about 50 pulses per pin, so yes you're right 'two gray code steps per detent"New terms for me,i appreciate the help on this, I'll check out that encoder you recommend, thanks again.

author: sudont
author_rank: Newbie
timestamp: September 17, 2020, 01:06:42 pm
content: Just to conclude the OP, I ended up using tweezers etc to try my best to straighten the contacts inside the encoder..and although the tests with multi meter showed strange readings, the original encoder works perfectly again.Thanks for all the input on this