Paper / Credit Card Shredder Fault

[spike47]

Hi
Have a problem with a Shredder, when switched on I put a sheet of paper into the shredder and nothing happens, but if I leave the paper in after a couple of seconds I can hear a buzzing sound coming from the relay then shortly after that the Shredder starts to work .
Will post pics and a drawing I have done ( not 100% sure it is correct !) any help on how to test it.

PS: Just a bit more info checked the voltage across the relay when switched on with paper in the slot and got a reading of around 8v , then it started to build up to around 15.8 v then the relay kicked in and it started , prob would of gone up to 24v if left meter on after it started ! .

cheers
Spike

 

[simpleGuy]

How old is this device? Since C6 is in serial to the relay I would assume that there is something wrong with one or multiple capacitors. The relay will only close (turn on) when C6 is fully loaded according your schematic. I would watch the voltage if its slowly raises and if the relay closes after a certain amount of voltage depending on the relay specifications. If its the case I would change/renew all 3 electrolytic capacitors and try my luck.

-simpleGuy (Trainee)

 

[spike47]

How old is this device? Since C6 is in serial to the relay I would assume that there is something wrong with one or multiple capacitors. The relay will only close (turn on) when C6 is fully loaded according your schematic. I would watch the voltage if its slowly raises and if the relay closes after a certain amount of voltage depending on the relay specifications. If its the case I would change/renew all 3 electrolytic capacitors and try my luck.

-simpleGuy (Trainee)

Hi
Thanks for your reply, yes I was thinking that me be the case, will now do that and see if that works , not sure how old it is , it is my Fathers , it will prob be more on the old than the new .
Just a quickie , does the yellow caps have anything to do with powering the relay or is it just the 3 E caps, and also I can't figure out how the 240v "L" feed gets fed to the PCB , it goes onto the PCB but then it is fed to the Motor from there, can't see it being fed to anywhere else on the PCB !.

Cheers and thanks again for your feedback.

Spike

 

[simpleGuy]

Hi, no the yellow ones are probably for sieving and smoothing the AC voltage. Electrolytic capacitors especially those black ones break down easily after a few years.
If I change capacitors I mostly use Polymer-Aluminium Electrolytic capacitors, they are more reliable. But you can use the exact same ones just new. Will work also

 

[spike47]

How old is this device? Since C6 is in serial to the relay I would assume that there is something wrong with one or multiple capacitors. The relay will only close (turn on) when C6 is fully loaded according your schematic. I would watch the voltage if its slowly raises and if the relay closes after a certain amount of voltage depending on the relay specifications. If its the case I would change/renew all 3 electrolytic capacitors and try my luck.

-simpleGuy (Trainee)

Hi
Changed all the Caps, no luck and it does not even switch on after awhile like before, have done a better schematic .
am thinking of trying to bypass the ir circuit on the board and make up a seperate ir proximiter circuit to feed direct to the 24v relay on board !, need a schematic for it first though, there is plenty of room inside the Shredder .
cheers
Spike

 

[M.Joshi]

With the shredder off, does the thermal switch read low Ohms or a short across it?

 

[spike47]

Hi
Am at work at the moment, the shredder works fine in reverse and works fine if I bypass the relay ! the ir diode is not lit also, that is what feeds the photoelectric diode ! .

ps: attached a revised Schematic
cheers
Spike

 

[alec_t]

Should D6 be reversed? (I don't see how the transistor gets a base voltage to turn it on).
The relay coil is shown shorted.

 

[spike47]

Should D6 be reversed? (I don't see how the transistor gets a base voltage to turn it on).
The relay coil is shown shorted.

Hi
Thanks for your feedback, yes you are correct had it wrong we round , sorry for the confusion .

pp: attached revised Schematic .
cheers
Spike

 

[M.Joshi]

Your diagram is confusing with the use of GND symbols connected to an AC line.

Are you sure the supply to the IR emitter is obtained from the live feed via a motor winding?

Do you have a photodiode or LDR? You have used the symbol of an LDR.

 

[spike47]

Hi
Thanks for your feedback, this is my first attempt to draw a schematic using AutoDesk Eagle, the ground symbols are meant to be the “Neutral” I don’t know what other symbol to use, yes the live feed to the board is through the motor winding .
Yes it is a Photodiode, that was the only symbol I could find in the Eagle library.
Cheers
Spike

 

[M.Joshi]

No problem. With the shreedder off and unplugged, have you tested the transistor and diodes using the diode function on a multimeter?

 

[spike47]

No problem. With the shreedder off and unplugged, have you tested the transistor and diodes using the diode function on a multimeter?

Difficult to check the Diodes on board

Di

 

[spike47]

No problem. With the shreedder off and unplugged, have you tested the transistor and diodes using the diode function on a multimeter?

Difficult to check the Diodes on board

 

[M.Joshi]

Difficult to check the Diodes on board

Due to size or location?

 

[simpleGuy]

D6 can still not be a Z-Diode but nevermind. Can you put your multimeter to diode/beep mode and check the C -> E and E -> C pins on the transistor (while no power!)? If it beeps, then the transistor is probably broken, to be 100% sure you have to solder it out then check again the C and E pins. A good transistor should be something like X Mega ohm between C and E, only when it gets the base volt & base current (turned on) it becomes almost 0 ohm.

Cheers,
sG

 

[spike47]

D6 can still not be a Z-Diode but nevermind. Can you put your multimeter to diode/beep mode and check the C -> E and E -> C pins on the transistor (while no power!)? If it beeps, then the transistor is probably broken, to be 100% sure you have to solder it out then check again the C and E pins. A good transistor should be something like X Mega ohm between C and E, only when it gets the base volt & base current (turned on) it becomes almost 0 ohm.

Cheers,
sG

Yes sorry D6 should not of had the Zener symbol next to it, will change drawing to show that, tks.

 

[spike47]

Will check the transistor as per what you say and come back to you .

cheers
Cheers