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Model Forum / General / Models / February 2009Bridgeport Electrics Check Please
Need some help please to check a problem, on a J-head Bridgeport with 2-speed motor. Contactor C3 for spindle motor should be normally open shouldn't it? - and then latched closed under signal power from (momentary) PB1 push button for motor start? I'm getting continuity across both terminals of PB1 all the time, whether it's pushed or not. I've taken the switch apart, and the mechanical side is working as it should, i.e. closed until pushed, so I'm thinking the problem may be with the contactor. Was operating it as usual last week, stopped to change drill sizes, then when I went to start the spindle motor again it tripped out the MCB on the fuse box, and had done the same everytime since. > Need some help please to check a problem, on a J-head Bridgeport with > 2-speed motor. [quoted text clipped - 11 lines] > then when I went to start the spindle motor again it tripped out the > MCB on the fuse box, and had done the same everytime since. don't know mate all i can do is relate my experiences .. 1. ...every Bridgeport "Ive" seen ..which is not many, have different electricals 2 ...motor can can short out to earth ..through the cover over the motor wiring connections 3. transformer for lighting ...this can go down ...and trip mcbs 4.feed motor contactor on mine seems to pull in ...and stick..in the on position sometimes..........never the spindle motor . all the best.markj >> Need some help please to check a problem, on a J-head Bridgeport with >> 2-speed motor. [quoted text clipped - 28 lines] > >all the best.markj Electrics match the schematics in the manual pretty well, just need to check that my electrical dyslexia hasn't kcked in. And to make a correction to my original post, the push buttom mechanicals are open until pushed, not closed as I first wrote. Peter >>> Need some help please to check a problem, on a J-head Bridgeport with >>> 2-speed motor. [quoted text clipped - 36 lines] > >Peter Peter, I can't give you any very specific advice as I haven't got a BP anymore, but start by electrically 'removing' bits of the machine and re-test to isolate the problem. The first obvious thing to do is to un-plug the spindle motor from the elect control box (mine was plugged in to the top of the box). If it then pops the MCB you know the problem's not 'beyond' the elec. box & vice versa. That has just reminded me - I did have a problem at one point with the socket into which the motor plugged. One of the wires inside it shorted to the elec. cabinet and gave the result you are suffering. Worth checking... I don't see why a stuck contactor should cause the problem, the motor would start as soon as the machine is powered (not correct obviously) but that still shouldn't pop the MCB. Rgds Richard > I'm getting continuity across both terminals of PB1 all the time, > whether it's pushed or not. I've taken the switch apart, and the [quoted text clipped - 4 lines] > then when I went to start the spindle motor again it tripped out the > MCB on the fuse box, and had done the same everytime since. Peter,the continuity you are seeing won`t be across the pushbutton.One side will be getting fed across a coil somewhere in the panel. As someone else mentions,if you`re not sure how to fault find this,start by disconnecting the motor from the panel and work back..Is this a standard machine on three phase as all the Bridgies I have seen had a five position rotary switch for controlling the motor. >> I'm getting continuity across both terminals of PB1 all the time, >> whether it's pushed or not. I've taken the switch apart, and the [quoted text clipped - 11 lines] >this a standard machine on three phase as all the Bridgies I have seen >had a five position rotary switch for controlling the motor. Mark, it is a standard machine with the 5-position rotary switch, running off a phase convertor in my garage. The push button energises the Motor start contactor/relay. Anyway, thanks for all the advice. I was competely wrong as usual, and isolating the motor has isolated the problem to the motor. It seems I have an earth fault in there somewhere, as any one of the 'live' positions on the 5-position switch gives me continuity between the motor live feed and anywhere on the machine.... So is it rewind time or could it be as simple as opening the motor up and fixing a bit of broken insulation? Any clues as to the next stage or sequence of fault finding? Peter > >> I'm getting continuity across both terminals of PB1 all the time, > >> whether it's pushed or not. I've taken the switch apart, and the [quoted text clipped - 30 lines] > > - Show quoted text - probably the simple ...as i sugested in my answer "2" it may be as simple as this .once this lot gets a bit of dust on it .. http://img.photobucket.com/albums/v190/aboard_epsilon/bridgeport/bridgewire1.jpg they short out to the cover http://img.photobucket.com/albums/v190/aboard_epsilon/bridgeport/bridgewire2.jpg clean all the muck and dust out, add double layer of insultion tape ..or you can shorten the posts http://img.photobucket.com/albums/v190/aboard_epsilon/bridgeport/bridgewire4.jpg all the best.markj > Mark, it is a standard machine with the 5-position rotary switch, > running off a phase convertor in my garage. The push button energises [quoted text clipped - 12 lines] > > Peter Peter, take the three phase wires of the five position switch.Test them to earth.Then test the wires going to the motor to earth.If the motor side is the faulty one,you might be better getting someone to look ast it if you`re not too sure.If disconnecting the rotary switch make a very careful note of the connections. If the motor has seen better days you can use a standard 3 phase 1.5HP flange mount motor if you extend the shaft (which isn't hard) This with an inverter might be cheaper than a rewind. http://farm3.static.flickr.com/2322/2364408633_88200c066f_b.jpg Charles |
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