19
Apr
'12

Sometimes I manage to impress myself bigtime.

A while ago, I left a comment on Jimmy’s page on Robot War, about Arena, which is basically* Robot War for the PC. This morning I received an email from Core War fundi John Metcalf, saying that he’s never heard of Arena, and would like to know more.

So I thought about it for about half a cup of coffee, remembered which box it was most likely to be, retrieved the box from behind the Puma, and the disk I was looking for was about the tenth disk down (this was the lucky bit — there are about 200 disks in there I guess).

The key point here is that I last used these disks on my father’s PC (the one before the one before the one he has now — it was a 386 on one of those motherboards that still took a 287 coprocessor) back in the early nineties. Call it twenty years plus tax.

The fact that I can’t find a notebook battery that I had in my hand day before yesterday is not relevant to the story.

So then I had to fire up the third machine on my desktop**, click the KVM over, and copy the files to something my main machine can read.

Now I know for a fact that the vast majority of my readers (both of them) are suffering MEGO with a side of TMI. So here’s a cut line for you. It gets geeky on the other side.

* Bad pun. Should be assemblerly. You don’t get it. Don’t worry. I’ll explain it.

** Primary machine is a Windoze 2K box. #2 is my Linux box, and #3 is a 486 (or maybe an early Pentium) which mostly boots DOS (with Windows 3.1 if I really need to do that) and runs my Expro.

(no, those were footnotes. And only a bit geeky. Here’s the cutline)

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15
Apr
'12

This is the 6871W1S113E control board from our LG MG-604W microwave. The transformer primary went open circuit when the supply hit 300V or thereabouts. I know that these things often incorporate some kind of protection circuitry, so I desoldered the transformer.

Sure enough, it’s a 1A 130C fuse.

Fixed (yea, this solution doesn’t have thermal protection. I can live with it).

Of course, now that I know the layout I know that one can add a fuse or a jumper to the PCB without having to desolder the transformer. Again, you’ll lose thermal protection.

The transformer primary is between the left and middle pins, and the fuse runs from the righthand pin to the lefthand pin.

I was not so lucky with the Sakyno SK-1000 clock radio. In this case the transformer primary was the protection device, and the magic smoke leaked out.

The Philips AJ3121 clock radio transformer has a fuse as well, the wire leading down on the right hand side goes over to the other side, where there’s a square  125C thermal fuse wrapped up against the winding.

It’s at the left hand side under the red tape under the plastic.

Unfortunately I stuffed it up, I jiggled the wire too much and the primary winding, which is cat-hair-thin, broke off from the fuse lead. I tried resoldering it but it’s just too finicky.

So we bought two new clock radios. But at least the microwave works.





14
Apr
'12

So on Friday the 13th we get home to some strange effects. Turning just about anything on makes some of the lights go brighter. The fridge affects the garage lights. The geyser affects the kitchen lights…

Having a working knowledge of 3 phase power, I realise that the neutral wire has come adrift*. Check the box, all looks good. Check the outside box, nope, neutral is floating out there too.

So I unplug everything I can, phone City of Capetown, they’ll send a team. All good. We go out Friday night. We go out Saturday morning. Get back, no change.

I get on the roof, check the wire where it comes into the house. No, problem is definitely on the pole. Phone council again.

Well, they eventually pitched at around 1900 Saturday. And after some stuffing around, found the problem (where, according to them, a previous team had taped over a potential problem which then a few years later hecause a real problem).

These teams are amazing. They still had four jobs lined up tonight, fellow says they get to the depot at 2200 and home at 2300, then are back on the job at 0600. But I’m glad to say he says the pay is good.

Casualties: pretty much the little things that are permanently connected but draws little power — the microwave, two clock radios,  computer speakers, the wall wart for the telephone…

* When neutral is not connected to the transformer, a load on one phase pulls neutral towards the line voltage, and in doing so pulls neutral away from the other two phases. The loaded phase falls to say 120V while the other phases go up to 300V or so (relative to neutral).