Sweep Drifting problem

[LaRue]

82-70. The sweep keeps drifting causing interlocks. Even after it finnishes it's cycle and goes back to the up pos. it drifts back down. I have tried replaceing the caps., gearbox, MP chassis, motor. I have also checked the wireways for any foriegn objects, replaced all the pins in the C1 plug, checked all the cam switches. I am in the process of going over the schematics. It is acting like the brake is not activating. Any IDEAS would be appreciated. <I AM AT MY WITS END>

[Ed Fox]

Re: Sweep Drifting problem

Check the plug at the motor for a broken wire or bad pin.

Charlie [img]/content/btubb/images/%%GRAEMLIN_URL%%/smile.gif[/img]

[pat]

Re: Sweep Drifting problem

Ed hit it! I had something like this last year and year and it was a broken wire in the table plug making intermittent contact. Two weeks to find a five minute fix.

Isn't that the hardest thing about fixing 8270's it is always more work finding what is wrong than it is to fix it.

Best of luck LaRue!

[LaRue]

Re: Sweep Drifting problem

DUH, i think that is probably the only thing i have not thought of or checked. Thanks. any other Ideas out there if that does not resolve my problem. please let me know.

[JimDorsin]

Re: Sweep Drifting problem

What type of switches do you use? You said you changed the motor, but do you still use the centrifugal switches?? Or do you use an after market type like the quality SS or Potentials? If you used the same switch, that could be the problem, but since you didn’t state anything about the switch, It would only stand to reason that yours are still in the motor its self. Just a thought though

Good luck, and let us know

[LaRue]

Re: Sweep Drifting problem

I'm using electronic. I am so tired right now that I can not even think of the name. I'm at home so I can't check. It's been a rough day.

[JimDorsin]

Re: Sweep Drifting problem

The solid state switches (little black box usually velcroed to the side of the stator) are notorious for causing drift, especially in the sweep, as it stops and starts 4 times as often as the table. (they will go bad faster on the sweep) Many different companies manufacture these.

If it is a black box about 2 X 2 X 2 inches, with 5 wire terminals on the top ranging from double to quad, it is probably a General Electric potential (most commonly referred to as the 'Stahls switch') If you are running Westinghouse motors, it may be a combination of the switch and the motor. I had the same problem in Vermont, but I left shortly after it started happening, so I never found the result. It would do it with different relays, motors, and chassis. out of 36 lanes I installed them, it happened on about 5 machines, and only on the sweeps. Those 5 I just converted back to cent. mech and switch with the intention of figuring it out over the summer...Then I moved.

See if one of those above is what you are dealing with, it might be the problem.... Good luck!!

Get yourself some sleep, i bet the problem will jump right out at ya as soon as you walk in the door, happens to me all the time...lol

Paul

[LaRue]

Re: Sweep Drifting problem

Thanks, will look it over (again) today. will post the fix when I find it.

[jez]

Re: Sweep Drifting problem

one thing, the point at which the cent mech or solid state switch closes on spin down is crutial, if it closes after the residual field in the stator has collapsed it will not brake properly, putting a capacitor across an AC supply pulls a lot of current, because if the line is +/- and the capacitor is charged +/- when the wave passes and the line is -/+ the line has to charge the capacitor to that polarity and it is this load that is used to stop the motor, immidiatley after power is switched off the motor will generate an amount of electricity, this is then fed into the capacitor(s) and as its generating an AC waveform which is fed into a capacitor, the capacitor pulls a load thus consuming the inertia in the armature and stopping the motor, or slowing it down to such a slow crawl that the gearbox drag does the rest, if the cent mech pops too late, after the field has collapsed there will be no braking effort and the only thing stopping the motor will be friction/drag, if the sweep is on a downward stroke, it will pull the motor round with it.

if you want the motor to stop like a demon, put a 2 pole double throw relay, (connect the NORMALLY CLOSED poles in parralell with the switch cards) fed from the contactor coil supply, so as soon as the contactor closes the relay contacts open and the capacitor is finally taken out of circuit by the switch cards, but, when the contactor opens, the secondary relay closes instantly connecting the capacitor to stop the motor, the motor will stop asif someone jammed a broomhandle in its fan!

you can get really cleaver by using a single switchcard to operate a relay and build a device that dosent open the relay contacts until the cent mech operates the switch card, but closes the relay contacts hard as soon as the contactor drops out/opens

this is a bit cumbersome, but it works like an absolute charm and is DIRT CHEAP!, if you want to get even cleverer, you bin the switch cards altogether and get a small timer that will switch on after it has been fed with power for 0.8 ish seconds, put that in line with the relay feed off the contactor and it will start your motors for you, pretty much trouble free!, if you use plug in relays, you just bin them when they wear out, at the princley sum of sub one quid (pound)

[Kat]

Re: Sweep Drifting problem

Jez:

This sounds interesting...

Can you post a crude or detailed schematic on this? I might try this.

[John_Galt]

Re: Sweep Drifting problem

Teeth on sweep shaft worn down to nubs?

[jez]

Re: Sweep Drifting problem

i will draw up a basic schematic at work tomorrow

this is a feindishly simple trick, but incredibly effective!

[LaRue]

Re: Sweep Drifting problem

Ed, you nailed it on the head. Had a bad socket on the plug, and Jez I sure would like a copy of that schematic also.

[LaRue]

Re: Sweep Drifting problem

Thanks for everybodies help.

[LaRue]

Re: Sweep Drifting problem

Oh, Jim we are using the AMF solid state 4 wire. have'nt had any real problems out of those.