Help sourcing a replacement part, possibly obsolete and not much to go on. - Page 1
Forum section: electronics / repair

author: charlie292
author_rank: Newbie
timestamp: April 29, 2020, 10:06:08 am
content: Hi all,I'm repairing a radio stack from a flight sim (an old Cirrus 2, from precision flight controls for those in the know!), a couple of the dials used to tune the radios and other bits are either broken or snapped completely.What I'm after appears to be a resolver rather than an encoder, I'm only guessing based on the number of pins it uses (3 per shaft) and the ones that do work, if you turn them too fast it just can't cope, which screams resolver to me. I don't have much to go on and all my googling is currently drawing a blank, I suspect the part is obsolete but anything that will do the job will do, I just want it working again even if it takes a little modding.I've added a couple of photos, but there isn't much to go on, I cant see a manufacture (just what looks likes a star symbol) and all the numbers draw a blank for me. If anyone can help out at all I would really appreciate it. No response from the precision flight controls which is a bit annoying.Thanks all!

author: Manul
author_rank: Super Contributor
timestamp: April 29, 2020, 11:29:24 am
content: Well, if some of them are broken anyway, why not try to dissasemble one. It seems that you just need to remove these plastic rivets to lift bottom side and have a look. That would be a useful hint of what it is.

author: coromonadalix
author_rank: Super Contributor
timestamp: April 29, 2020, 12:10:08 pm
content: Seems to be an OAK Grigsby encoder, maybe an optical one ?https://www.electro-nc.com/oak.cfmhttps://www.electro-nc.com/products/index-b.shtml

author: Yansi
author_rank: Super Contributor
timestamp: April 29, 2020, 12:12:14 pm
content: No, not a resolver, by a long shot.Its a boring mechanical quadrature encoder with mechanical wiper on PCB. You can see even the quadrature contact arrangement on the back side of the PCB.The other set of 3 wires - not sure what for, isn't it a dual encoder? or a pot/encoder combo? Or dual shaft?

author: charlie292
author_rank: Newbie
timestamp: April 29, 2020, 12:37:21 pm
content: Quote from: Yansi on April 29, 2020, 12:12:14 pmGlad someone knows what they're looking at, I just assumed it was a mechanical resolver due to how they reacted when you turned it too fast.It's dual shaft like you say hence the 6 pins. I just now need to find something that will replace them now.

author: charlie292
author_rank: Newbie
timestamp: April 29, 2020, 12:39:13 pm
content: Quote from: coromonadalix on April 29, 2020, 12:10:08 pmThanks, I've made an inquiry with them, can't seem to find the actual part on their site so will see what they come back with. At least if I can get a pin out or something from them I can make something else fit if I need to.

author: Yansi
author_rank: Super Contributor
timestamp: April 29, 2020, 01:01:24 pm
content: Quote from: charlie292 on April 29, 2020, 12:37:21 pmNo. Look how a resolver works and how does it look like. There is not any RPM limitation, definitely not in the RPM range you could produce by hand turning it. Resolvers are routinely used in applications over 10k RPM.

author: charlie292
author_rank: Newbie
timestamp: April 29, 2020, 01:08:03 pm
content: Quote from: Yansi on April 29, 2020, 01:01:24 pmIt might be the software then, but when you turn these too fast they just respond funny, like winding down rather than up for instance.Either way, my mistake, however can you explain why these only have 3 pins per shaft whereas most other encoders normally have 5 pins?

author: Yansi
author_rank: Super Contributor
timestamp: April 29, 2020, 01:18:20 pm
content: Other two pins are either due to mechanical reasons (stability, stiffness of component mounting), or they are use for the push-button - remember some encoders can be pushed and the switch uses the two additional pins.Classic electro-mechanical encoder does not need more than three pins: A common (ground) and the two A and B tracks that give the quadrature pulses.Funny response on these electro-mechanical encoders is mostly due to excessive wear on the contacts, that give intermittent signals.