Crook electric wiring

I couldn't agree more with the sentiments expressed in your Publisher's Letter (March 2003) about dodgy electrical wiring. We have just had a 3-storey building refurbished and rewired by professional electricians. To describe their work as a "pigs' breakfast" would be too good for it. This is fast becoming the rule rather than the exception in jobs I've seen lately.

In days of old, sparkies were required to be relatively neat in their work, however work standards seem to have started to really go down hill since late 1998. In this particular project, wires are held up above the new suspended ceiling via disused old suspended ceiling eyes, clipped every metre if you're lucky. TPS cable is hanging down to the 3-pin troffer lighting sockets which are slung in mid-air. On the upper floor, the cabling runs above the safety wire mesh that is below the insulated sarking under the roof. Not to mention the new TPS building cable that has about half the insulation of the old stuff!

Those unlicensed people such as electronics technicians, etc who know how to change a power point or run an additional circuit are in danger of being found out simply by the fact that their work is too neat and tidy!

Where's this all going to lead? I don't know but one thing is for sure and that is that no pro sparkie can bleat about unsafe wiring practices if what I've seen recently is what is now the normal standard produced by these people.

Name supplied and withheld at writer's request.

Bureaucracy gone mad I am writing with regard to the issue of the Queensland contractors electrical licence required for electronics repairers and the Publisher's Letter in the March issue concerning the proposed banning of electrical cables, switches, power points, etc from public sale in Victoria. This is bureaucracy gone mad and is a direct result of the apathy that pervades our society. Having worked in the medical industry, I have witnessed first hand what happens when bureaucrats get involved with a system that has previously worked well. All bureaucrats work on the same lines of reasoning. We must protect you as a consumer from the unscrupulous or from yourselves. We are here only for your good. This sounds wholesome but they are there for the purpose of regulation and control, to gather revenue and to perpetuate their organisation. These new regulations in Queensland smack of restrictive and anti-competitive work practices and government-sanctioned monopoly. It may be quite illegal and should perhaps be tested in the High Court of Australia. Unfortunately, we as techo's are a politically inert lot, more satisfied at wielding the soldering iron and oscilloscope probe than the pen, much to our detriment. Also, the Restricted Electrical Licence should be beefed up a little and be available to technicians having completed recognised courses in electronics - so as to legally enable them to carry out their professions and be permitted to carry out electrical wiring in their own homes. Basic electrical wiring is child's play to a qualified technician. Finally, is Australia a truly democratic, free enterprise clever country or are we becoming a grossly over-regulated society? M. Whitenight, via email.

ETI-480 amplifier a faithful old dog

In your articles on the SC480 (January & February 2003) you say that the ETI-480 Amplifier Module was a "dog" of an amplifier and that it was not a good performer, but there is another view. I'm a bass guitarist and since 1986 I've used a pair of ETI-480s running in bridge mode. Two dogs are usually better than one and this is definitely true with these modules. Together they run a full 100W RMS into an 8W heavy-duty 38cm loudspeaker.

I've done many hundreds of gigs with them; they've been faithful companions and have never let me down. However, they do develop a bit of a smell during the warmer months. I was a bit stingy with heatsinks and the specified 1W rating was never going to be sufficient for R16 and R17, the 33Ω emitter resistors for the driver transistors. I've since replaced them with two 68Ω 1W units in parallel.

Several years ago, I tried upgrading to a higher-powered MOSFET module and a much bigger power supply but it sounded too pure, too tight, too dead for my setup. It felt like trying to play golf with a set of clubs whose shafts had no "whip".

The MOSFET module works much better for vocal PA and I'm still using the 480s for bass. I would really love to build the new SC480 module but there's every chance that the old dogs will outlive their master.

Neil Hobbs,
Mitcham, Vic.

Piano tuners need an electrical contractor I am very concerned about needing an electrical contractor's licence to do electronic repairs. In 1976, I gained my Electrical Fitter Mechanic certificate, after a 4-year apprenticeship with O'Donnell Griffin in Concord West. I studied at Penrith Technical College and then at West Sydney Technical College in Petersham. After a year and a half more with the company, I left to change direction and gained my Certificate in Piano Tuning and Technology at the NSW State Conservatorium of Music in 1981. I've now been working in piano servicing and technology for 23 years. During that time I've noticed electronics and 240V entering into pianos. Usually, this is a computer-based system or a climate control system. Sometimes it may be for show or display lighting. The computer types can be a disk recording playback system, or for silent practice, digital piano circuitry can be added to some pianos so one can hear the piano in headphones while the piano's hammers are stopped short of hitting the strings. Secondly, 240V gear can be found in pianos, where a humidifier or dehumidifier has to be installed. Both computer and climate systems can be found in uprights and grand pianos. So, under the proposed new rules, where do I stand? Should I have the qualifications to renew plugs, sockets, etc and check safety? Presumably there should be some provision for people like me to show a certificate and be able to buy fittings from an electrical supplier. Paul Smith, Albert Park, Vic. Comment: at the moment, the electrical contractor licence requirement only applies in Queensland. But the legislation there needs killing before it spreads to other states.

Exploding motherboard capacitors hard to replace

I just read your article about exploding motherboard capacitors in the May 2003 issue. Unfortunately, it came a little too late. I manage the network for an Internet cafe and I recently diagnosed the capacitor problem on 20 of our motherboards. I read your article and you have covered the problem but not enough about the solution.

You mentioned the low ESR capacitors you can buy from RS but unfortunately they were all too big to fit on these boards (about 20 capacitors need replacing on each board). I imagine that most motherboards will have a similar problem as everything is squashed in as close as possible.

After many interstate phone calls and confused sales people, I found a suitable replacement. The Rubycon ZLH series provide a range of 1500μF capacitors which I managed to be able to get in an 8mm package from Tenrod Australia - see www.tenrod.com.au for contact details. The capacitors cost 60c each.

If enough people need these replacements Tenrod may reduce their minimum order quantities to make it a bit more accessible to someone with just one motherboard to fix.

Hope this helps!

Aaron Russell,
via email.

Shotgun service techniques not desirable As I read the Serviceman's Log each month, I am concerned at the "shotgun" techniques used. If there is something wrong with the sound, he will simply change every component in that section. This is usually without any attempt to trace the fault. Maybe this is normal practice these days but it reeks of the old "valve-jockey" approach where a junior employee would exchange valves in the hope of fixing something. Sets that failed to be fixed like this were then passed to an "expert" for serious diagnosis. The man makes a living I guess but should this approach be recommended to readers by publishing accounts of it? Mike Murphy, by email. Comment: the Serviceman stories "tell it like it is" but we will let our Serviceman reply in person: I think it has been said before that the definition of an engineer is someone who can make or do something for 10c that any damn fool can do for $1. Nowadays it is all about money and being cost-effective. Time is of the essence. You might be a genius and muddle it all out in your head before you fix it, and take all day doing so, or you might just change a few choice components that cost only a few cents each in five minutes. However, there are some tenacious faults that just won't reveal themselves by careful measurement and diagnosis, particularly those intermittent ones. I think it unfair to use the sentence "usually without any attempt to trace the fault". Furthermore, a faulty part can sometimes damage surrounding components and from a warranty point of view, it is only sensible to change all the related parts. If you only change the one faulty part and not the other vital components, the system may run but not to specifications, leading to further failure. Long experience and training gives one the knowledge to recognise common component failures that might not require too much research to pinpoint the fault. I'm sure most people would prefer to pay for the cheapest approach and they don't really care if it is scientific or shotgun.

It never rains but it bores

I found your PIC-based Rain Gauge in the September 2000 issue an interesting project, though I didn't build it for its original use. I wanted a controller for a bore pump. The pump has to fill two large tanks, if possible using only off-peak electricity. An added complication is that the pump can only run for six hours at a time otherwise the bore may run dry. If more than six hours pumping is required, it has to run during the day as well as at night.

Using the PIC gave me the opportunity to log the time that the pump took each day to fill the tanks and store this information for 61 days, as in the Rain Gauge.

In modifying and adding to the program, I found the source code very easy to follow, well commented and clearly laid out. In the hardware, you kindly left me one output bit unused that I required to control the pump, that 7th segment in the bargraph. Thanks for a great project.

Keith Gooley,
via email.

Project discrimination against front-wheel drive cars

As a subscriber and reader of your magazine over the years it has come to my attention that us owners of front-wheel drive cars (which these days are probably the majority) are being discriminated against when you publish automotive projects.

Any project is usually only designed and described for a tail-shafted car; ie, rear-wheel drive. I realise it is more difficult to put sensors on front-wheel drive cars but as there are not that many rear-wheel drive cars on the market any more maybe you could put your thinking caps on and come up with a solution. The latest project, the "Triptronic Gear Indicator" in January 2003, is but one example.

Ray Draper,
Canberra, ACT.

Comment: what a grievous accusation. We would never discriminate in such a way. In truth, while the diagrams may show a speed pickup attached to a tailshaft, exactly the same method can be employed with front wheel half-shafts, although it is more difficult.

In any case, in the Gear Indicator article you refer to, on page 43 we describe how to use the speed signal from the engine management computer. Virtually every front-wheel drive car produced in the last 20 years will have an engine management computer.

CRC 2-26 can catch fire

I write in response to a letter about WD-40 in Mailbag in the March 2003 issue. I agree with John (don't use WD-40), that WD-40 is a penetrating oil never designed for electronic use. Conversely, I do not agree that CRC 2-26 is NOT flammable. I once washed the engine of my car and pretty much saturated the distributor, inside and out, with CRC 2-26 when the ignition got wet and the engine wouldn't start.

Once it did start, within a moment I noticed a burning smell and a little smoke from under the (still open) bonnet. I discovered my distributor on fire! It was only burning for a moment and no damage was done except to some plug lead insulation, and a rag thrown over it soon put it out.

Significantly, no other product had been used on the distributor except CRC and obviously there were no residues from previous servicing, otherwise the distributor would have caught fire beforehand. There is no doubt the CRC 2-26 ignited, yet subsequent attempts to ignite a little of the liquid with a match failed and the container does say it is non-flammable.

My only conclusion is that it ignited maybe because the temperature or intensity of the arcing within the distributor was hotter than a match flame. I don't know.

Importantly, many of the water dispersant type products sold for auto use are oil-based, particularly the cheap products from discount stores, yet while they may be marked as flammable, they give no cautions about the potential for the incident I experienced.

Indeed, one such product I use is Australian Export WD Spray as a general anti-rust product and while the can is marked as flammable gas (which I suggest is incorrect labelling), it is indicated on the can that the product "acts fast to start wet engines". This product is distributed by Oweno Sales, NSW.

Incidentally, I was once advised by a mechanic not to use these types of products on tools to prevent rusting, since they are hygroscopic (absorb water) and therefore will attract water in a humid atmosphere and actually cause rust, rather than prevent it!

Peter Cahill,
via email.

Isolation of CHMSL lamp failure circuit Those readers building the LED centre high-mount stop light (CHMSL) from the March 2003 issue may be interested in the following. On a 1991 Camry/Apollo, this circuit can be isolated by removing one 2.2kΩ resistor from the PC board in the Lamp Failure Box which can be found in the righthand side of the boot. It can be unplugged from the wiring harness and is easily dismantled. There are three 2.2kΩ resistors which go to the sensing circuit on the PC board, one for Stop, one for CHMSL and one for Tail and Number (combined). Identify the CHMSL and remove the appropriate resistor; all other functions remain unchanged. Readers with similar vehicles may like to try this modification. R. Sonter, Bundaberg, Qld.

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