As I understand it, there are 9 of us Gizmo owners who have the Hall-effect throttles which go along with the Sevcon PP745 SepEx controllers. Hall-effect throttles are essentially a non-wear item. The only thing that should ware on them is the pivot point of the trigger and the return spring. The proximity of a magnet to the sensor changes the output voltage of the signal line which the controller then interprets as a torque value. A really great setup, actually.
Mine has been working flawlessly until about a month ago. The throttle started cutting out at various times. Sometimes this was when I was attempting to accelerate from a stop, sometimes it was when my variable regen cutout (I posted about this in March/April 2009), and sometimes it was while I was driving along at a constant throttle. Once in a while it would quit when I hit a bump or slapped the side of the handle. I took the handle apart and took the Hall-effect sensor off and couldn't see anything immediately wrong with it except that the back of the case was dented where the screw mounts touched it.
Prior to removing and reinstalling the Hall-effect sensor the cutout issues were somewhat random but not quite. Afterword, however, it seemed that the throttle would cut out when the trigger was pulled fully on. This seemed strange but I figured I must have wiggled something inside the unit in the removal/installation process. I clearly needed a replacement.
Carl said that they purchased the handles as complete units so I went to my list of bookmarks and the original parts supply spreadsheet and found a website for Sure Grip Controls, Inc. I emailed the sales department and told them I need the hall-effect part. They replied that they only sell through dealers and that Pape' Machinery right here in Kelso, WA was a dealer. I stopped by the next day and naturally the Gizmo was a topic of conversation for a bit. The sales/order rep was very helpful and said that he had an order for Sure Grip going out the next day so I could get the part without added shipping. Awesome! Found that the part only comes as a kit and that the last item he ordered with it in it was about $125. Ouch. I don't have a choice and knew that even if it was over $100 that it would be cheaper than having someone build one from scratch so I had him order me the kit. It is part number PC-V2-T-KIT. The Whole kit is shown on the left and a close-up of the individual parts is on the right.
I checked the readouts on the Gizmo Interface and other than the "zero" point being slightly higher it worked as needed. The Gizmo Interface already had a buffer programmed in so that "zero" was a little above the low voltage of the original hall-effect and it was enough to accommodate the slight difference.
Now that I had a working throttle I was a little more willing to take apart the old sensor. I carefully pried the FRP cover off and then slowly pried the contents out of the gray plastic box. Then I removed the glue (which is like silicon rubber) off the back and then the front. What I discovered was that the actual hall-effect sensor it self had a broken solder joint on one of the pins.This may have been a weak point to begin with or it could have just broken after the sensor moved slightly every time full throttle was requested. One of the mounting screws is also right beside the connection so when I reinstalled the unit after my initial inspection I probably tightened the screw a different amount and with the compressible potting material the joint might have made better contact, at least to the point that only when full throttle was requested did the connection break. I re-bent the pin and re-soldered it. I also did my best to reattach a very tiny SMD resistor I accidentally cut off when prying the edge of the potting compound off. I hooked up the circuit board to my power supply, gave it 5V and measured the output. It puts out the original 0.82V to something over 2-3V. I didn't try too hard to get the trigger magnet in the right place since I don't expect to need this any more but I'm satisfied that it works somewhat.