Foxindebox 461 Posted January 18, 2018 Hi Guys, I need some help from somebody with electronics experience. I’ve started to restore an old Brenray cleaning machine and need to re-wire it as the speed control Rheostat isn’t connected properly. I thought I’d use it as an excuse to renew the switches, light and replace old wiring. There are a few pics below, any advice as to completing the wiring diagram and what type/rating components I would need to buy would be greatly appreciated. I have disassembled and cleaned the motor, greased the bearings and replaced the bushes. The motor runs well but obviously I can’t adjust the speed. Cheers Share this post Link to post Share on other sites
ShovelnTC 31 Posted January 18, 2018 So when you say the rheostat isn't wired correctly what do you mean? Does the voltage not change when the knob is turned? Is the motor actualy spinning? I can't see where the neutral goes to the motor only the active and I can only see the neutral going to the heating plate circuit. The AC/DC motor is confusing me though! Share this post Link to post Share on other sites
Foxindebox 461 Posted January 18, 2018 The motor is running strongly after cleaning, just at one speed... the Rheostat has x3 terminals but only two wires going to them. It’s basically working like an on off switch at the moment, there is no gradual reduction in speed Share this post Link to post Share on other sites
ShovelnTC 31 Posted January 18, 2018 I believe the 3 terminals are for when a specific start speed is required so you only wire to 2 of the terminals but when the out wire is on one of the 3 then your voltage will have a full resistance (0 - 220v) but when wired to the other it will have a part resistance (110 - 220) or (0 - 110) or that's how i THINK they work. First step would be to test resistance across the stat with all cables disconnected and put your Ohm meter across the terminal and turn the knob to see if it is varying the resistance. Try it on the various terminals and see what you get. Share this post Link to post Share on other sites
Not Quite Dead 9 Posted January 18, 2018 And always remember the knee bone is connected to the leg bone. Having tried to wire a fan extractor plus light in a bathroom into the existing light circuit I have decided I will stick to plumbing, wood work and every form of building stuff apart from thins with electrical bits. Share this post Link to post Share on other sites
BadPickle 2,657 Posted January 18, 2018 Two terminals are either end of the resistance the third is the wiper. You’ll only use 2 terminals, the wiper and one other http://www.globalspec.com/learnmore/electrical_electronic_components/electronic_components_passives/potentiometers_rheostats Share this post Link to post Share on other sites
MetalMickey 179 Posted January 18, 2018 I’d definitely take electrical advice from people on the internet Share this post Link to post Share on other sites
Foxindebox 461 Posted January 18, 2018 Thanks so much for all your advice guys, I really appreciate it 1 hour ago, metalmickey said: I’d definitely take electrical advice from people on the internet They know more than me... which isn’t hard Share this post Link to post Share on other sites
ShovelnTC 31 Posted January 19, 2018 Keep in mind that a big chunk of electrical training is safety! Even so I've seen so much dodgy work by so called licensed electricians that it is truly scary. Share this post Link to post Share on other sites
Foxindebox 461 Posted January 25, 2018 Update: Thanks to @rollie who sent me a picture of the wiring of his machine (which is the same as mine, I have deduced the rheostat is fucked... I’ve cleaned the contacts but am only getting power when in contact with the one terminal, there is no juice the minute I move the arm. @pickledbeetroot @ShovelnTC The rheostat I’m going to need as a replacement is 50W/750 Ohms which im finding impossible to source. I have found one with the correct Wattage but the resistance is either 800 Ohms or 1KOhm. The question is, would this be suitable in your opinions? Cheers Share this post Link to post Share on other sites
ShovelnTC 31 Posted January 25, 2018 I expect that the 800ohm will be fine as it will simply give a slightly lower lowest speed than the old one but I'm dipping out from giving further advice as my work usually only involves AC motors so I don't want to confuse things. With those old motors and devises make sure the insulation and grounding of everything is good and invest in an inductive voltage tester so you can check everything once switched on without actually touching anything that may give you a shock. AND when using it be sure you have a residual current devise either in your homes electrical circuit or if not buy a portable one. Share this post Link to post Share on other sites
Foxindebox 461 Posted January 26, 2018 8 hours ago, ShovelnTC said: I expect that the 800ohm will be fine as it will simply give a slightly lower lowest speed than the old one but I'm dipping out from giving further advice as my work usually only involves AC motors so I don't want to confuse things. With those old motors and devises make sure the insulation and grounding of everything is good and invest in an inductive voltage tester so you can check everything once switched on without actually touching anything that may give you a shock. AND when using it be sure you have a residual current devise either in your homes electrical circuit or if not buy a portable one. Cheers mate, much appreciated Share this post Link to post Share on other sites