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The MAZATROL

This 6 tonne Mitsubishi NC lathe had stopped working shortly after being purchased after the Ford factory shutdown. Its 27 year old computer arrived here with desperate entreaties to fix it. The 17 big chips with taped over windows looked really suspicious and the assumption was that they had lost their program.

After changing IO boards and poking around James demanded to see the thing malfunctioning and after checking wires back through the relay panel and reading the instruction book an extra wire was discovered going over to the other tool turret that indicated lock.

Our suspected MOS problem turned out to be a hydraulic problem caused by some grot getting under a solenoid and leaving a bit of torque on a hydraulic motor so the turret could not settle.

Fake Batteries :-(

There in the scrap lead pile was a pallet of demonstration batteries from Battery Energy. Rainbow Power Company were always throwing out good things and I assumed these were old dry charged units they could not risk selling. So I bought vast quantities of acid and rinsed dust out of them with distilled water and attempted a charge. Nothing but gassing! After more failure someone pulled one apart and found the problem - no paste.

I thought they felt a bit light ...

woodwinds

Well it is a type of windpower ..... after making a new barrel for a "Rampone" clarinet (Milan ~ 1880) we got more ambitious. James has designs on a Serpent, and Kali has actually landed a Rackett - aka Wurst Faggott. It is a ridiculous instrument that proceeds to impossibly low notes in a series of woody farts. The main problem from an engineering point of view was that some of the 12 holes were unreachable and needed levers and pads. Some also needed elevating from the surface of the instrument on litle tubes.

As this computer (Slackware 10) at last is running ALSA you might get a multimedia experience next edition with both a picture and a recording of this "Sausage Bassoon".

iPOD :-(

For ages this iPOD hung around. First it was the wrong cable, then the wrong operating system, and then at last a net connected XP machine appeared and we tried to put some music on the iPod. After much irritation that worked, but the earphone was so microsopic and overpacked we did not see it. Grabbing one of the myriad of computer speakers around we connected the iPod but instead of music we got that brown smell ....

The computer speaker had the wrong plugpack with the wrong label in the wrong hole, and there was a nasty little direct bypass switch on the speaker to conduct the 12vac into the poor SOT output. Expensive. And the only thing you can do is rant about the idiocy of the audio plug "standards". What bright spark started using 3 mm signal plugs for modem ac supply ??

CARBON FILM RESISTORS!

This week has seen the failure of two computers and an oscilloscope due to resistor failure. Carbon film resistors after a certain lifespan simply stop conducting with no external signs. It seems unrelated to temperature, but does seem to be a matter of voltage and possibly humidity.

Finding the culprit requires perseverance and reasoning, and often the failure has been slow and erratic, damaging other related components. It is infuriating seeing a $1000 bit of gear brought down by a component worth 1/10 cent.

The remedy is to use metal film resistors, but this is probably precluded by the "race to the bottom" situation in globalised electronics manufacturing. Also Flowtrack boycotts metal film resistors because the blue body makes the colour stripes unreadable. (why would anybody...!). The only solution seems to be to use the expensive metal oxide film resistors which are magnificent. They still work red hot ...but yes, the colour stripes become unreadable!

DRIVER TROUBLE

A recent wind repair was caused by a lift vehicle driver who did a great job of getting the turbine up but then sort of wanted to get it more than up and kept driving!

The back stay gave under the strain and the machine followed the pull vehicle at rapidly increasing speed until a final resting place in the paddock :-(

PETROL TROUBLE

An essential part of remote area electronics is of course getting there, and the old workhorse I drive has over half a million Km on it. It is a petrol/LPG 1600cc Toyota: cheap to run and easy to repair. It had been working perfectly on gas but randomly going badly on petrol - nothing below half throttle. Everybody said "put a new carbie kit in it!" MISDIRECTION 1: The petrol pump had failed last year and an attempt to get home by gluing it had resulted in muck clogging up the final filter in the carburettor. MISDIRECTION 2: The vacuum line to the distributor was clogged with dirt. After disassembling the carburettor and cleaning it (twice) I at last worked out that it could be an air leak, not a fuel blockage - no vacuum means no petrol. The car could still run well on gas because the idle fuel is delivered by the gas system with regard to nothing except continued ignition. A loose manifold flange, and a dodgy pipe from the crank case ventilation looked the culprit. But it was not :-( Finally the car stopped idling on gas and I drew the right conclusion: .....valve seat recession. The inlet valves were not closing perfectly. The engine was not missing on a cylinder or two as you would expect, but there was the manifold leak - back from the combustion chamber! We all tell stories of how ignition faults can mimick fuel problems, but here was a valve problem mimicking a fuel problem.

TURKEY TROUBLE

There was an open circuit on the Malapiki Microgrid. Nice solid 50 sqmm PVC coated twin set off up the hill with 100 volts DC on it, but the other side of the sea of lantana there was no voltage :-(

After crashing down the hill through the lantana it became apparent that the crossing of Tuntable Creek had been pulled down near the ground by the clambering bastard weed. That should not have caused an open, so the scratchy exploration continued. there was the fault: - it was about four metres across and a metre tall - a Bush Turkey nest!

The day was about 40 degrees, and the Turkeys nest was made from damp hoop pine needles and was so hot as to be a danger to walk on. Yes, the voltage was disappearing under the nest and after some excavation it was obvious that the cable insulation had melted and the metal disappeared into the compost.

So, Turkeys are not only able to crap, scratch, knock bottles off shelves , honk, "fly" around inside houses, upturn garbage bins ....... they can melt cables!

Another remarkable shot from left field

..... the serviceman

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