Photo Sensor problem with "Royal" paper shredder

[5030tinkerer]

Happy New Year! I am having a problem with a paper shredder - basically, the photo sensor that "detects" paper in the shred path to turn the motor on, doesn't. I took it apart, noted paper "dust" all over the sensor, cleaned it off, and things worked well for about a month or so. Then, same problem. Took it apart, found it to look clean, and ended up using the reflective properties of aluminum foil taped in place over the sensor to get it to turn on. That worked for about six months.

Now, I am just dead in the water.

Questions:

1. Does anyone know where you can get replacement sensors?
2. Assuming this thing works by reflected light, can I just clip the supply wires to each side of the sensor and hard wire it to just turn on in the auto setting? Manually pointing the sensors directly to each other does not turn it on.

A somewhat fuzzy pic of the sensor pair is attached - note that it is designed such that the sensor sides are angled into each other at 30 degrees or so, seemingly to pick up the reflection.

 

[duber34]

Happy New Year 5030tinkerer.

My step daughter has a paper shredder that had problems with the paper "detector" as well. I don't recall what brand shredder it is as it's been about 2 years since I worked on it. Same problem as yours; the shredder would not turn on in auto mode when paper was inserted in the slot. If I remember correctly hers had a mechanical switch. (Someone tried to cram too many pages in at once and busted the switch as well as the plastic mounting clips) I simply removed the switch and hard wired around it. With the switch removed, the shredder runs continuously in auto mode. I instructed my step daughter to manually turn the shredder on when she wants to shred and to turn it off when done. I also told her not to dally when she has it turned on as the motor will heat up and thermal off. The shredder is still in use...... Good luck with yours!!


Regards,
Duber

 

[5030tinkerer]

Hey Duber! Thanks for the response!

I had *wanted* to hard wire around it like you were able to (and still, I guess, do), but expected (hoped) to see a simple mechanical switch when I got in the first time like what you had. Since this guy uses a photo switch (with two leads wires to each side of the photo detector [they look sort of like LED's, but don't seem to be]), I was unsure whether I could just join the wires from each side of the detector (creating two connections). Sadly, these four-total wires are part of a substantially larger molex plug that is inserted into the circuit board making all the decisions.

I was tempted to just go ahead and hard wire it this way and take my chances (figuring it is "broken" now anyway), but had hoped to find someone here who had already tried this particular thing or had some level of additional comfort that I wouldn't take out the control board.

 

[duber34]

Hi 5030tinkerer,

Sorry I couldn't help you out more. My gut tells me that you probably would be fine hardwiring around those "LED's". Most LED lamps of that size (I'm guessing about 5mm) only draw 20-50 milliamps on a couple of 3 to 6 volts DC. Now, I generalize. Of course some draw more and some draw less so it is still a gamble. I was going to suggest maybe just replacing the LED's until I read your comment about them not really seeming to be LED's....... Anyway, RadioShack has a small assortment of LED lamps and here is a site: AOPLed.com LED Lamps Thru-Hole

Good luck!!

Regards,
Duber

 

[5030tinkerer]

Hey Duber -

Thanks for the GREAT site link! I learned something new today (does that mean I get to go home now? Oh wait, I AM home. <grin>).

Turns out what I was confused re: the LED's is what the guts of an LED looked like. The blue 'oval-type LED lamp' closeup shot at AOPLed.com LED Lamps Thru-Hole shows these guts and mirrors what my two lamps on the shredder look look.

I will run over to the local Radio Shack and pick up a pair of replacement lamps, but now I am really curious how this thing works.

I HAD been under the impression that there were "sending" and "receiving" lamps; that is, that the one lamp sent light out at 30 degrees inward and the other lamp "saw" the reflection of this light when paper was inserted into the paper path and that somehow a circuit was completed.

Evidently, it works some other way, but I'd love to know how.

I also wonder if there is some benefit to getting brighter LED's than what Royal shipped with it to allow the unit to "see" better.

Any thoughts? Any thoughts on how a multimeter could be used to test LED's? Likely only one of them is shot.

 

[mbohuntr]

Disclaimer: I am not a repair person. I accept no responsibility for your actions. I recommend a qualified repair shop. That being said...I think you may have a IR (infared)transmitter/receiver pair or LED/phototransistor pair. You will want to find the side that recieves the signal and try to figure out what it is. You can initiate a response either by making, or breaking a beam, so the receiver is the one to get bypassed. put a meter across the leads on the reciever to find the voltage. If it is conducting, you should get .7 volts . if not, I believe you will get supply voltage. if you are getting .7 volts I am thinking there may be other issues. Keep the meter on the receiver and break the beam w/a piece of paper and watch the response. The receiver voltage will change when the beam is broken. If this does not start the shredder when the voltage changes, you got other problems. I would also look for an internal fuse, and check it for continuity after you remove it. (unplug first of course. I only possess college classroom expierence and NOTHING else. Keep this in mind.

 

[5030tinkerer]

Thanks for the great post! I'll have to check the voltage like you said and see what joy that brings. Meanwhile, I've attached a much better picture of what I've got. The hope is that I can tell WHAT I had - IR send/receive pair, LED send/receive pair or what. Any thoughts on how I can determine this? There don't seem to be ANY markings on what I have here to go off of.

Thanks!

 

[mbohuntr]

Unless you can get the schematic from the internet, I'd avoid replacing with something like a guess. A diode is a one way valve for (DC)electricity. A transistor is kinda like a valve. nothing flows until the handle is cranked. That crank can be light, voltage or current.
If you have an "emitter" like a LED,or a transistor "collector", if it is not conducting, the meter will show higher voltages than if it is conducting.(think of voltage as "pressure", high means no or little flow) now if you aim the lights at each other, block the path, and one 's voltage changes, that is your "collector", A light bulb doesn't dim when you cover it, but a light sensor will. The "collector" is what is what is controlling your motor.
We're talking DC here, if you get a negative number on a digital meter, don't freak, switch the meter probes. Diodes typically will drop some voltage when they're conducting, so I will not recommend shorting the leads. There are much more knowledgable people here that can point you to a safe solution.

 

[5030tinkerer]

Unless you can get the schematic from the internet, I'd avoid replacing with something like a guess.

I haven't had any luck finding any schematics...

now if you aim the lights at each other

I haven't yet checked voltage, but can tell you that aiming the two 'lights' at each other did not cause the machine to turn on.

so I will not recommend shorting the leads.

My planned next steps are to check the voltages to see what that brings, but I'd be nearly as happy to just know how to wire around it. It certainly would have been great if it were a simple mechanical switch...

 

[irvingj]

Tinkerer-- if it were mine..... No, I'm not a qualified service repair tech, but often repair stuff anyway.

mbohuntr is most likely correct, the "LED"s --one a transmitter, the other a photoreceptor-- use IR light for this purpose-- pretty common. The problem is, LEDs and photoreceptors rarely go bad, in my experience. I suspect the problem lies on your logic board.

Short of replacing the control board, and again, if it were mine, I'd look on the circuit board for the relay that most likely controls the motor, identify the contacts that perform that job, and solder a jumper on it to keep the motor switch circuit energized all the time, and plug & unplug the machine as necessary.

Note that this is definitely NOT the safe way to do it, but it should work. You'd have to take necessary precautions to ensure that no one would use it that wasn't aware of the situation. (Kinda like jumping out the seat safety switch on a tractor--be careful!)

Short of such drastic measures, I'd be looking to the manufacturer for advice and/or parts. Who makes this thing?