bmw cd23 (bp3850) rotary encoder replacement - Page 1
Forum section: electronics / repair

author: kat1337
author_rank: Contributor
timestamp: April 28, 2025, 01:35:25 pm
content: Hello It's a common issue with this model and rotary encoder is some kind of not common type as I've tried random ones just matching voltage and number of detents but it's not working properly - I mean it works but that's far from factoryI've made schematic if this helpsMaybe there's some different output type encoder that I don't know or it is possible to modify the original circuit to make today's standard encoders work with it

author: Jeff eelcr
author_rank: Frequent Contributor
timestamp: April 28, 2025, 09:51:54 pm
content: Spray cleaner not working, disassembly clean +lube usually works.If not, factory reman or buy another radio.Jeff

author: Peabody
author_rank: Super Contributor
timestamp: April 28, 2025, 10:06:33 pm
content: Quote from: kat1337 on April 28, 2025, 01:35:25 pmIn what way does it not work properly?

author: kat1337
author_rank: Contributor
timestamp: April 28, 2025, 10:40:54 pm
content: Quote from: Jeff eelcr on April 28, 2025, 09:51:54 pmI've tried - not working/same result

author: kat1337
author_rank: Contributor
timestamp: April 28, 2025, 10:43:03 pm
content: Quote from: Peabody on April 28, 2025, 10:06:33 pmIt behaves like it's not recognizing the direction when I put the replacement one in. Sometimes it works but you have to turn it very much and also sometimes decreasing volume works but increasing doesn't

author: Peabody
author_rank: Super Contributor
timestamp: April 28, 2025, 11:01:46 pm
content: That usually means it isn't wired correctly, or there's a break in the connection to one of the switches. I guess it's possible something is wrong with the replacement, but you can test for that with your multimeter.Is it possible that the original encoder is working properly, but the problem is somewhere else?

author: kat1337
author_rank: Contributor
timestamp: April 28, 2025, 11:16:46 pm
content: I've tested many types of encoders alps bourns nonames but only the original one from my friends unit worked properly so I think problem lies here. As I see the wiring is same as with today's encoders so..

author: Peabody
author_rank: Super Contributor
timestamp: April 29, 2025, 02:33:03 pm
content: Well it just seems odd. After all, an encoder is just two mechanical switches, plus a push-button switch. If a series of modern encoders don't work, it seems likely that you have the wiring wrong. The pinout of the original may not be what it appears to be. Have you tested your friend's original encoder with your multimeter to see if you get continuity where you expect it? That should be easy for the push button switch, which by elimination would identify the rotary terminals.Just guessing of course, but there's no reason why any replacement wouldn't at least work electronically if it's wired correctly, unless the original has some magical properites.Google "rotary encoder only works in one direction" and see what you get.

author: tooki
author_rank: Super Contributor
timestamp: April 29, 2025, 03:11:30 pm
content: There was the recent EEVblog video about encoders that were not standard quadrature encoders, but rather ones that produce discrete up/down pulses depending on the direction of rotation — essentially, a drop-in replacement for up/down buttons. Any chance it could be this? At least it’d be super easy to test: just short the corresponding common and A/B pin and see what happens.Or use an oscilloscope to record how the working encoder from your friend works.Here’s the video:

author: kat1337
author_rank: Contributor
timestamp: April 30, 2025, 08:00:23 pm
content: I unforutnatelly don't have osciloscope :// but when I short A or B to middle one it works as it should - the question is where I could find part that behaves like that.edit: just watched the video above... it's very possible that's the same output type I am looking for especially it's from this era and also made by germans just like the blaupunkt (makes sense for me)I think best way to do it is to measure the output with osciloscope and propably emulate this kind of output from normal encoder through arduino