Nissan March/Micra Stuck Shift Lock Repair

The shift lock is the mechanism that keeps the gear shift stuck in PARK unless the ignition is on and the foot brake is depressed.  There is also a manual override button, I guess intended for allowing the shift to neutral for towing etc even when the car is switched off.

For some time now, we’ve been resorting to the manual release button because the automatic mechanism doesn’t work.  (2003 Nissan March)

The mechanism is pretty simple.  Circuit diagram here: Micra K12 manual page 3912 on manuals.co .  There is a solenoid (black/white wires) in series with the brake switch, and a  microswitch (blue/white wire) that is closed when the shifter is in Park.

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Getting access to the mechanism is a matter of removing two screws either side of the centre cover at the rear (push seats forward to access). Lifting the cover from the back will pop out the two clips at the front.

Using a continuity tester I found the microswitch wasn’t closing when the shifter was in park. However, pressing it more firmly caused it to close.  Probably the plastic cam that presses the switch has finally worn too much.

I fixed this by moving the shift out of Park, and carefully bending the microswitch lever up towards the cam.  The above photo shows it closed now.

 

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Kenwood HB720 repair

Our Kenwood HB720 hand blender suddenly stopped working. The punchline of this post is that inside its excruciatingly-difficult-to-dismantle mechanism (i.e. never intended to be repaired), it includes a fuse, which had blown.  This post will be updated to give the details about how to take the machine apart, and whether I managed to reassemble it after replacing the fuse.

So, if “the motor is broken” on yours, it may just be the fuse that has blown.

One sign that the fuse is probably blown is that a diode test with +ve on phase, -ve on neutral shows open circuit when the Turbo button is pressed (this button bypasses the speed controller, and connects mains power via a bridge rectifier to the DC motor).

Dismantling

Tricky. There are a couple of videos purporting to show how to dismantle it, but I reckon they both are filmed after the unit has been dismantled and reassembled.

First remove the drive-end cover.  This is held in place by three  hooks on the inner plastic part, that engage with square holes on the cover.  One is above the ejector wedge on the side without the number stamped on it. The others are 120 degrees round from that. You might be able to get this cover off just by pulling very hard, but otherwise probe with a small screwdriver(s) to push the hooks inwards and disengage them.

The inner part is glued or welded in to the body.  This thing is a prick to get out. I attacked it with a screwdriver and a scalpel, and still it looks fairly munted.

Carefully prise off the speed control knob at the cord end.  This reveals 4 screws, to be removed. Turn over the plastic circle with the cog and undo the 2 screws to release the cord clamp. Slide the knob and clamp up the cord.

Now push on the plastic tray holding the circuit board, pull on the motor shaft to remove the motor + speed control assembly.

Electronics

So here’s the speed controller board

The fuse is inside black heatshrink “FR-H TUBE 125C”.  It is soldered to the board.

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The blown fuse
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The speed controller

A strange thing is that the fuse is rated at 1.6A, while the machine is nominally 700W.  Unless I’m missing something, 3A at 240V is 720W, so either Kenwood is lying about the power rating, or the fuse rating is too low?

I replaced the fuse with a piece of wire, because I’m not planning to open this up again.

Links

Schematic (polish)

Another set of photos about dismantling and assembling HB720.  Pretty good,  the inner and outer drive-end covers are shown still connected together. I doubt it is possible to remove them in this state.

Repair of Kenwood FP481 Food Processor

This is a follow up to my previous post.

Thanks to need a part, I got the spare parts I needed to repair the food processor. The price was enough to make me wince! : Upper drive belt $19.95, Upper cog $18.95, P&P $7, (+ Hand Blender geared lid $19.95).  But a combination of bloodymindedness and marginally OK economics meant I went ahead with this anyway.

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Out with the old and in with the new.

The drive belt is a direct replacement, but the toothed pulley is made for a shaft with 2 flats on it.

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Old pulley used nut to stop it spinning.

The new pulley lacks the square nut cage, so I can’t just drill it out for the round shaft.  I’ll grind the shaft down instead.

Success!

Now lets see if I can remember how this all goes back together.

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Reattach the motor to the top plate
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Attach the interlock mechanism
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And the interlock circuit board

Then reattach the on/off/speed/pulse switch.

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Done!

The final step is to put the bottom of the case back on and I’m back in business.

Success!