Init Paper Shredder sensor circuit

[davg]

Re: Init Paper Shredder sensor circuit

That cap is for the DC power supply for running the electronics on the board.
So from the picture: This must be reverse-able motor.
The Yellow and the Green wires are for the motor's brushes?
The Blue and White wires are for the Stator motor winding?
The slide switch on the board, is that for forward/reverse motor function if you have paper jammed?

That is correct it is reversible? The slide switch is Auto - off - reverse. When set to auto the sensor starts the unit

[999999999]

Re: Init Paper Shredder sensor circuit

lol, I am reminded how much of a headache I get trying to trace circuits from random pics. Can you trace the circuit back a bit and with power off, measure resistance with the slide switch flipped one way, then the other? Looking at the switch contacts as two columns in the picture of the back of the PCB, the first two rows of contacts in each column should read very near zero resistance between each other when the switch is flipped that direction, and vice versa for when the switch is flipped the other direction.

[budm]

Re: Init Paper Shredder sensor circuit

That is common function for shredder, my has the same but it uses micro switch for sensing paper.
Any how, you are reading only 57VAC on the brush connections? They may have the Stator and the rotor winding in series setup.
That is why good clear pictures are important when you do not have the board right in front of you.

[davg]

Re: Init Paper Shredder sensor circuit

lol, I am reminded how much of a headache I get trying to trace circuits from random pics. Can you trace the circuit back a bit and with power off, measure resistance with the slide switch flipped one way, then the other? Looking at the switch contacts as two columns in the picture of the back of the PCB, the first two rows of contacts in each column should read very near zero resistance between each other when the switch is flipped that direction, and vice versa for when the switch is flipped the other direction.

Forgive me put on the attached picture which contacts should be near zero resistance?

[budm]

Re: Init Paper Shredder sensor circuit

Does the motor run the same speed in both direction? If it does, then that will eliminate the contact resistance problem.
When the slide switch is in the left position (base on the picture with numbers)
1 and 2 should be 0 ohm.
5 and 6 should be 0 Ohm
when move it all the way to the right position
3 and 4 should be 0 Ohm
7 and 8 should be 0 Ohm

[davg]

Re: Init Paper Shredder sensor circuit

Does the motor run the same speed in both direction? If it does, then that will eliminate the contact resistance problem.
When the slide switch is in the left position (base on the picture with numbers)
1 and 2 should be 0 ohm.
5 and 6 should be 0 Ohm
when move it all the way to the right position
3 and 4 should be 0 Ohm
7 and 8 should be 0 Ohm

The motor do run the same speed in both directions. The resistance is 0 ohms on these contacts with the switch in the designated position. Just to confirm; To supply 120 vac to the 120 volt motor, the yellow and the green is L1 and L2 with the Blue and White being the two field poles. How would I connect it to bypass the board?

[selldoor]

Re: Init Paper Shredder sensor circuit

When you say the motor runs slow what are you comparing it with?.
How long does it take to shred a sheet?

[davg]

Re: Init Paper Shredder sensor circuit

When you say the motor runs slow what are you comparing it with?.
How long does it take to shred a sheet?

That is compared to when it worked properly. About 10 sec working properly to approx 40 sec now.

[selldoor]

Re: Init Paper Shredder sensor circuit

ok i believe normal max is about 3meters per minute. Is there any detail on the motor that might help us find the specs for it?

[budm]

Re: Init Paper Shredder sensor circuit

Can you remove the motor from the assembly so you can run it without the load, and since it uses the gear reduction to run the shredder assembly, can you crank the assembly by hand using the same gear that the motor is attached to just to find out how hard it is to move the blades.
I believe the stator and the rotor windings are connected in series, and they reverse the direction by switching either the stator or rotor winding connection.
I still do have the time to draw up the wiring diagram yet.

[999999999]

Re: Init Paper Shredder sensor circuit

He could also check voltage across a different combo of wires going to the motor to see if any combo is at ~ 120VAC. Since the cutters turn ok with the gear removed it seems as though either not enough voltage is getting to the motor or it has a short in the windings.

OR what I mentioned earlier, that the blades are really dull and it's choking on the paper which would make it run significantly faster with a narrow piece of paper vs a full width piece.

[budm]

Re: Init Paper Shredder sensor circuit

Good suggestion, 9999999.

[davg]

Re: Init Paper Shredder sensor circuit

He could also check voltage across a different combo of wires going to the motor to see if any combo is at ~ 120VAC. Since the cutters turn ok with the gear removed it seems as though either not enough voltage is getting to the motor or it has a short in the windings.

OR what I mentioned earlier, that the blades are really dull and it's choking on the paper which would make it run significantly faster with a narrow piece of paper vs a full width piece.

Thanks all the motor runs the same with or without load. Gears removed or paper in? The problem is either in the motor or in the board. As soon as I can find a drawing to hookup the motor straight and bypass the main board I can narrow down the problem even further.

[budm]

Re: Init Paper Shredder sensor circuit

I am beginning to think the same as 99999 that the motor may have shorted turn in the windings.

[budm]

Re: Init Paper Shredder sensor circuit

By the way, that big white power resistor 0.6 Ohm is in series with the motor, can you check and see if it read less than 1 Ohm?

[budm]

Re: Init Paper Shredder sensor circuit

OK, I figured out how it works, see simplified diagram attached.
The Rotor winding is connected in series with Stator winding, depend on how you connect them together, you can make it run forward or backward by reversing the Rotor winding connection, very simple, as long as the two windings are in series, the motor will run.

[selldoor]

Re: Init Paper Shredder sensor circuit

Have we mentioned checking the brushes are not too worn or are the slides clogged with dust so the brushes are not seating correctly. When it is running are there a lot of sparks from the commutator, I recall you did say you had cleaned the gaps.

[davg]

Re: Init Paper Shredder sensor circuit

OK, I figured out how it works, see simplified diagram attached.
The Rotor winding is connected in series with Stator winding, depend on how you connect them together, you can make it run forward or backward by reversing the Rotor winding connection, very simple, as long as the two windings are in series, the motor will run.

Thanks for the drawing budm great job. Problem solved. The problem was with the motor as someone indicated (cheap motor). I removed the motor completely and dissembled it to find that the wire connection to one of the brushes was broken. and one of the bearings was worn badly. I can replace the brush but the bearings are actually bushings and finding a replacements could prove impossible? Cheaper to buy new.

[budm]

Re: Init Paper Shredder sensor circuit

Well at least you know how it is wired up now, I thought you had check the brushes in post 9 and indicating that they were OK. Live and learn.

[davg]

Re: Init Paper Shredder sensor circuit

Well at least you know how it is wired up now, I thought you had check the brushes in post 9 and indicating that they were OK. Live and learn.

Thanks again and yes I did check but I only removed the one on top easy to get at?? (making to many assumptions) your are right "live and learn". That drawing is a useful thing to have around.