After around 7 or 8 years of some tough abuse and shredding my Fellowes PS-77CS Shredder has finally given up the ghost and failed on me.
The machine is getting power, but it doesn’t run the shredder motor. There are signs of power going to the device, because it detects win the bin is open and lights up the red light to say it’s open. The light goes off when you push in the Micro switch so this tells me the sensor circuit was working fine and the problem was more electrical as opposed to mechanical.
I did some dismantling of the actual equipment. Fairly simple, lift it up and remove about 10 screws. Open the lid then disconnect the wire attaching the motor to the PCB. I did a quick look around the circuit and couldn’t find any specific issues.
I finally identified the problem, I went to remove the PCB so I could look up the schematics and when removing it the transformer was literally hanging on a couple of threads of copper wire. So it came off easy enough (picture below)
I decided to remove it, as it was evident to me the transformer is what caused the problem. For those who don’t know, a transformer receives an incoming voltage in a circuit and then alters it for the output side (either by increasing or decreasing it). In this case, it’s receiving an input voltage of ~ 220v and outputting it into ~ 15.6v from what I can find online (these are the specs). I’ve wrote them below if anyone finds them useful.
Input Voltage: 220V
Output Voltage: 15.6V / 15.6V
Dimensions ???? : 8 * 11 (On other sites, this number translates as “specification” – so I think it’s the size)
No Idea ???? : 3 + 4 (On other sites, this translates as “stitch / work type” – not sure if this means the number of pins)
Now, when researching online, it seems these transformers are commonly fitted to the Fellowes shredder models and seem to be the weak point of them. The point of failure is usually when the shredder falls over or gets banged about a bit. The transformer / PCB are mounted upside down in the shredder motor. So if the unit falls over it can damage it. Essentially it’s dangling on it’s own internals.
A common fix suggested by one user seems to be fitting an M2730 transformer, which is slightly bigger then hot glue it in place so it doesn’t damage it if it falls. I looked up this product and unfortunately it’s a discontinued product. So I may try places like eBay or Farnells / CPC in the UK to try and source one.
In the meantime I have emailed Customer Support at Fellowes to see if they stock spares. I’m more than happy to fit the equipment myself to get it up and working again. Failing that I’ll source one online if they cannot supply. The equipment by Fellowes is amazing. It’s stood up to some tough abuse from myself, but I’d rather not pay £ 100 for a new shredder if I can fix it myself for around £ 20
I’ll update this post as I go, hope some of you find it useful and helps you on your quest with your Fellows PS-77CS Shredder or others.
PS: If your from Fellowes, I’ll happily receive a new shredder from you if you offer me one. I wouldn’t complain 🙂
UPDATE 2021
I’m actually still looking at this, my knowledge has increased over the years. The problem I’m having is sourcing a transformer with the correct pitch / pin spacing and size enough to fit into the array. I’ll keep this article updated should I find it, as I’ve been wanting to repair it.
For information the Chinese sites list it as follows
Input Voltage: 220V (Chinese sites like this as Enter, I’m guessing entry voltage)
Output Voltage: 15.6V / 15.6V (It is a dual 15.6v transformer – the 15.6 is UNLOADED voltage)
Dimensions ???? : 8 * 11 (On other sites, this number translates as “specification” – so I think it’s the size)
– Still not sure, I think this could be referring to the gauges of wire (8 gauge, 11 gauge)…. still looking
No Idea ???? : 3 + 4 (this translates to the pin count – 3 primary, 4 secondary)
EXTRA INFO
Pitch – 5mm
Row Spacing – 20mm
There is 20mm between the primary / secondary pins, and 5mm between the terminals of the secondary pins
(On other sites, this translates as “stitch / work type” – not sure if this means the number of pins)
For information – it uses an EI28 transformer core
UPDATE#2 – 31/08/21
This shredder is now FIXED. I basically decided that if the shredder was no longer working, I may aswell not worry about the board and just try to bodge it.
For reference the transformer I used is a Vigortronix VTX-121-3223-215 model.
I’ll be uploading some pictures, because to fix it the way I’ve done it, you need to be prepared to damage/repair your own board in order to fit the transformer.
The problem is the pin pitch/spacing on all the modern transformers, I ended up cutting holes in the board and bending pens, then running wires to join them up. I’ll probably upload a Youtube video detailing this for further information
I also had to make my own Capacitor up for testing (which was a bad idea anyway). The capacitor I used was Electrolytic, and 330uF/400V, which turned out to be 55 x bigger than the factory one (but it worked for testing at least). It also explains why my shredder said it was overheating. I’ve since ordered the correct type for my shredder to be fitted.
A few notes along the way to help you out as these may be also questions you’re searching
Does the Shredder use a start capacitor or a run capacitor?
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- The Fellowes PS-77Cs uses a “run” type capacitor
What value is needed for the capacitor?
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- It should actually be printed on the Motor of the model (6UF/450V), the model that was fitted to my shredder was YY9050-2M23
- If you need to work out the manual way however, here is the formula
- Motor Wattage x Efficiency x 1000 / (AC Voltage x AC Voltage x AC Frequency)
- In this instance (180W x 80% x 1000) / (230 x 230 x 50) (Motors are around 80-85% efficient FYI just input this range)
- 14.4 Million / 2.645 Million = 5.44 Micro Farads (round up to 6)
