Elana Sky Dives!

This is Elana jumping out of a plane over Wollongong to celebrate her graduation from Uni.

Don’t you open that trap door!

Because there’s something down there!

I am of course refering to the secret trap door in the pokie room of the North Wollongong Hotel. I couldn’t help having a little peek down there the other night.

- Jared

Fridge Dramas

Having a lot of problems with our fridge and I have been trying to fix it myself so now I know a lot more about fridges then I ever wanted to. For instance did you know that a frost free fridge stays frost free by using a heating element to melt all the frost off the fins in the back of the fridge. Ours is supposed to heat up for about 30 minutes once every 10 hours.

But it doesn’t! As a result ice builds up where it is not designed to. After a few weeks air stops flowing into the fridge from the freeze since it is blocked with a slab of ice. As a consequence all the food in our freezer was fine but all the food in the fridge went off and since the thermostat is in the fridge not the freezer the whole unit runs 24 hours a day.

Check out the before and after photos of the ice. The before photo is after about 4 hours of defrosting. Before that I couldn’t get the back panel of the freezer off. The after photo is in another 4 hours and a lot of hair dryer work.

You can see the heating element at the bottom of all the pipes in the second photo. It was pretty obvious this wasn’t working and it could only be one of three components.

1. The element itself (unlikely) .

2. The defrost thermostat. That’s attached to the cool pipes in the top right corner of the second image. It makes sure that the heater only runs when there is actually frost build up.

3. The defrost timer. This is a device that has 4 terminals and acts like a switch that changes state for 30 minutes every 10 hours.

I shorted out the terminals on the defrost timer to bypass it as per the circuit diagram on the back of the fridge and bam the heater started up and ice started rapidly turning to steam! So it was number 3!

Here is what it looks like I found it under the panel that holds the temperature control in the back of the fridge compartment. You can manually turn the red rubber bit to advance the timer in and out of defrost mode.

Not to give up early I then pulled this thing apart and found myself with 6 cogs and 3 tiny axles on the floor. I soldered some dry terminals inside the thing and then spent an hour getting all the cogs back in the right places. It actually works by rotating an odd shaped circle using a brush-less motor geared right down. The odd shaped circle pushes different metal terminals together during its 10 hour revolution.

I put it back in the fridge and it started ticking!! FIXED!

1 week later it stopped again. Guess i will have to spend $70 and buy a replacement part

- Jared

A Cold Cold Wind

This was a few weeks ago now but I went for my next kite surfing lesson. Finally some decent wind! It was freezing but we got in for some body dragging. I am somewhere in the water hanging under the grey Switchblade II in the first photo and shivering in the second

- Jared

CrtIsValidHeapPointer

/*
 * If this ASSERT fails, a bad pointer has been passed in. It may be
 * totally bogus, or it may have been allocated from another heap.
 * The pointer MUST come from the 'local' heap.
*/

I got this interesting debug assertion the other day while removing an object from a queue in a window DLL. It all sounds fair enough I must be passing a bad pointer. This wasn’t the case the pointer was fine. Next option was that i wasn’t creating this object on the local heap. I was in fact pushing items onto this queue from another DLL so this could be the case but the function that pushes objects onto the queue creates them in the correct DLL using new and copies all the data passed in into this structure.

So this shouldn’t be happening!

The culprit turned out to be a CString. Even though i thought i was copying it into “new” memory the CString copy constructor and assignment operator just reference count strings until you change them. So even though i was passing a CString by value and copying it into an altogether new CString the buffer is still the same.

This is obvious in retrospect. Almost all string libraries perform shallow copies. The lesson never trust someones copy constructor to perform a “copy”

- Jared