Friday, September 09, 2005

My mate asked me to go and help him at work today, with the cabinet at the hospital we've been working on for a couple of weeks.

A quick recap.. we went in the first week, so I could work out how to use a laptop to configure the cabinet, this was fine.

After that, they found that the filters needed replacing, and they were replaced. In the process of doing that, the data cable between the controller PCB, and the front panel switches was damaged.

I repaired the cable, but then when we started the cabinet, the exhaust fan motor was wobbling all over the place, like the bearings were gone.

They got a brand new fan to replace the suspected failed one, and installed that, but it continued to shake all over the place.

So I went in today, to work out what was going on.

I tested all the connections, and traced the wiring, and I couldn't see what was wrong. I thought perhaps the motor had ended up being connected backwards, but swapping the active and neutral lines around made no difference.

I mucked around with the connection of the starter windings too, even leaving it disconnected, and spinning the fan up manually, in case the starter windings had somehow managed to ended up connected backwards, but this didn't fix it either.

There was an unused fan connector in the unit, and when I connected the fan to this, it spun properly, without shaking. I thought I had it figured out, that someone had connected it to the wrong supply.

We put the unit back together at this point, since it seemed to be running properly. This was a task in itself, because the conntections from the pressure sensors had ended up all mixed up, and I had to work out what was supposed to be using the normally open/closed contacts.

Once this was done, we started certifiying the cabinet, and it seemed ok. The fans were running a bit high, and when we tried to isolate one, both would run.

This made me realise that we still didn't have the fan connections correct, and that both were running off the same circuit.

I mucked around with it a bit more, but could only get the motor shaking when connected to the right supply.

What was even more strange, was that we still couldn't isolate one fan from the other (using the calibration software), and we couldn't adjust the speeds of them either.

I eventually decided to try connecting the fan circuits around the other way, to test if it was the fan causing the problem, or the controller.

When I did this, the other fan, which had always run fine, started shaking all around, and the new fan would run properly.

This confirmed my theory that the problem was nothing to do with the fan.

We gave up at this point, deciding that the controller board needs to be replaced, but this might be difficult, since the company that manufactured the unit no longer exists.

I suggested that the controller be overridden with a couple of normal hardware speed controllers in the unit, and bugger the software control.

We put the unit back together, and left it out of operation, and left.

We went over to a mate of my mate's place, and picked up his mate, who's doing some sort of a database course at Uni.

We went to the Uni campus, and he bought a DB book, it was groovy in the book shop there were quite a few interesting looking DB books.

On the way back towards home, I chatted with the guy, and looked at an assignment he's doing, where he needs to draw up an ER diagram, and the table structure for a database.

I got home, and grabbed my mate's xbox, that I've had for ages, and my laptop, and went around his place.

I setup the Xbox, patched it into his lan, and the projector, and showed them XBMC, they were pretty impressed.

We sat and watched an episode of Rome, that my mate had downloaded.

I got a call during that, from a mate's brother in law, having problems fixing his computer.

I hepled him out over the phone a bit, trying to identify the drivers he needed for his video card and modem.

After we finished watching Rome, I showed them some emulators I loaded on the Xbox, and we ended up playing Sega Master System games for a while, laughing while playing Paperboy.

I never thought I'd be playing Paperboy, projected 3 metres wide on the wall.

Another couple of mates showed up later, and we had a good time going through old Sega, Nintendo, and arcade machine games.

We went out for some drinks after that, since it was my mate's birthday a few days ago, but that's not technical content, so I end the post here.


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