Good luck with trying to get help with repairing it- I also have a Vigorhood VS1500CA cross-cut shredder, and all I can say is that the company is absolutely abysmal when it comes to service.
Mine is practically new, and started going in reverse... after unsuccessfully trying to get help from the retailer were I purchased it from, and also trying one of the main distributors in Singapore, and the manufacturer, Shenzhen Vigorhood Electronics Co Ltd in China (who didn’t even bother to reply to my query), I eventually resorted to opening it up.
The VS1500CA cross-cut shredder has very crude & cheap electronics inside- and because of its simplicity, and probably also containing the cheapest components they could possibly source when manufacturing it, there is a problem with their current sensing circuit (which is critical to the shredder’s operation). As a result of this, it is prone to suffer from drifting in sensitivity as it ages (though, it would also have a horribly indeterminate range that will make one shredder have a significantly different character to the next, even to start with when new).
For those with the same problem as what I had, I found that diode D7 (just next to the opto-coupler U3 and the 100k resistor) had drifted towards the lower end of the typical diode forward voltage drop... so I simply replaced it with an arbitrary diode that had a 0.56V forward voltage drop that I found in an old box of components (anything with a voltage drop that's close or a bit above this would probably also work fine).
Thor, April 2013
