rewinding a 900 ohm electromagnet relay component? - Page 1
Forum section: electronics / projects

author: coppercone2
author_rank: Super Contributor
timestamp: January 08, 2023, 08:08:34 pm
content: I have a 900 ohm solenoid from a relay I wanted to rewind.The dimensions of the electromagnet are 1.2 inch by 0.7 inch and the impedance is 900 ohms, it actuates a HP relay powered by 34V on a RC time delay circuit.The reason I took it apart is because it was showing low resistance to the chassis (20 meg) while the sister unit shows the usual infinity.The wire is very thin, measuring 0.109 mm on micrometer, which I believe corresponds to 38AWGhttps://www.coonerwire.com/magnet-wire/Is there a off the shelf cheap tool that can help me do this?Its about 1500 feet of wire to wind.I thought this tool might be good.https://www.amazon.com/PanelTech-Purpose-Electric-Machine-Counter/dp/B07FY9VVQF/ref=asc_df_B07FY9VVQF/?tag=hyprod-20&linkCode=df0&hvadid=242034450866&hvpos=&hvnetw=g&hvrand=4625980874370029592&hvpone=&hvptwo=&hvqmt=&hvdev=c&hvdvcmdl=&hvlocint=&hvlocphy=9003445&hvtargid=pla-597484096296&psc=1The shaft is 1/4 inch and the original part # is A-121907 (900 Ohms) By C.I. Clare & CoLike I don't want to buy that coil winder, I feel like I got jumped by this coil anyway. Last thing I was expecting to be bad because it looks great. I thought to just mount it in a drill and try to do it by hand , and hang a small weight on a rubber clasp over the wire so each time I wind a layer I can leave it tensioned. I don't plan on making any more then I have to, 1500 feet seems like alot, but since its just a relay I was going to pack it in to the same dimensions and hope it works.. so I don't need the turn counter.

author: jonpaul
author_rank: Super Contributor
timestamp: January 09, 2023, 01:26:04 am
content: 1. find sources and the leakage, possible water or dirt contamination I would dunk in 99% isopropyl alcohol2. easy to make a jig and counter, hand wind or variable speed motor.3. Such thin magnetics wire is costly and easy to break during winding.4. easier to just replace the solenoid5. We use only Adams Maxwell 120X winding machines, the best in the industry,$1500..5000 nowadays6. use a tensioner or dereeler.Jon

author: coppercone2
author_rank: Super Contributor
timestamp: January 09, 2023, 03:22:39 am
content: I guess solenoid is incorrect.Its just a electromagnet/rod inductor that has ALOT of turns to get 900 ohms. On top there is a lever arm which is forced down by the field.I tried to search for a replacement based on that part # but I can't find it. The relay has a momentary contact that is normally closed to a RC circuit, which charges the coil, and closes the contact (shorts out the RC circuit) and also closes 2 contacts (that connects amplifier output to front panel).I was going to replace it with 2x relay and some kind of delay circuit, but I figure I would give it a shot at rewinding it, since its quite nice.I think the part might be quite specific...

author: coppercone2
author_rank: Super Contributor
timestamp: January 09, 2023, 03:28:26 am
content: if you know a chassis mount electromagnet that has 1inchx0.72 inch dimensions and 900 ohm impedance, it might work to replace,or a relay that has 2x contacts that are normally open and 1x contact that goes from normally closed to normally open and runs at ~34V. Well actually I guess a triple relay would work, if you don't mind unnecessary contacts...Thought it would be easier to rewind it then to find a new relay and work out the situation with the delay time and weird power rail voltage.Since it passes a signal from the amplifier to the load, I am not sure what kind of relay I need, ebay is hard because its not a new chassis so it needs to fit in a fairly specific area.If you had an idea of a relay I could take a coil out of that would work too.

author: jonpaul
author_rank: Super Contributor
timestamp: January 09, 2023, 04:22:25 am
content: pix or schematics would be helpful....rewind ofm900 ohm relay or solenoid is not trivial . Applicantion, coil V,I,DC,AC?Contact load, V, I, AC,DC?j

author: coppercone2
author_rank: Super Contributor
timestamp: January 09, 2023, 06:39:48 am
content: the 1x0.7 inch cylinder goes in the middle there and pulls the left thing down so the contacts move. It just makes a field, there is no moving part on the electromagnet. It had a nub on top. That is dismantled now but it was just 2cardboard disks that were wedged into a rod (approx 0.245 inch diameter) on top and bottom to make the bobbin. The shaft/flux concentrator got screwed into the right of the relay in the pictureI cut out two teflon disks of a similar thickness to the cardboard and ordered teflon heat shrink to insulate the shaft so I can reuse the shaft and hopefully nothing else, I think that old cardboard might be dodgy.

author: jonpaul
author_rank: Super Contributor
timestamp: January 09, 2023, 06:47:43 am
content: this is called a relay.What's wrong with the coil?Where is it?j

author: coppercone2
author_rank: Super Contributor
timestamp: January 09, 2023, 06:48:57 am
content: It read low resistance to earth compared to two identical relays and I said it fell apart when I removed the shaft because it turned out not to be varnishedthis started with the GFIC was tripping and then I found that the unit had low earth isolation basically everywhere I measured compared to the other units. When I finally got to cutting the relay off, the readings between units became identical (open).one of the thoughts i Had is to put a solenoid there, instead of it, so it yanks the plate and makes the relay work anyway, but that sounds like its going to need some kind of pain in the ass mechanical adapter thing

author: Berni
author_rank: Super Contributor
timestamp: January 09, 2023, 06:56:48 am
content: Winding such a fine wire coil is going to be all sorts of difficult.You are better off just finding a relay with similar enough specs and replacing the whole thing.Or if this is some sort of fancy electro-mechanical setup that moves other things rather than just moving contacts, then i can see you would want to fix it. The easier path there would be to buy a few different relays and solenoids of a similar size and voltage, salvage the coil out of them, then bodge the new coil into the mechanism.

author: coppercone2
author_rank: Super Contributor
timestamp: January 09, 2023, 07:16:21 am
content: the wire I pulled out of it did not seem that fragile, which made me think I could do itFinding a compatible coil seems mad hard.Form factor to search for? Manufacturers?

author: Simon
author_rank: Unknown
timestamp: January 09, 2023, 08:39:51 am
content: https://www.eevblog.com/forum/repair/rewinding-900-ohm-solenoid/msg4626091/#msg4626091