Manual wanted for Osborne monitor

I am attempting to repair a 20-inch Osborne high quality monitor, type MON 020. It was given to me as it was not cost effective to have it repaired commercially. It has burn-ed induc-tors in the horizontal output stage and the horizontal output transistor and one other transistor on the heatsink have been removed by a previous repairer.

I realize that Osborne as a brand no longer exists but I feel that the monitor has some useful life left in it and would like to attempt a repair. Is there anyone who can help me with device numbers for transistors 7605 and 7615. (These are the numbers on the PC board.) The inductors I can rewind myself.

I would be happy to pay a reasonable amount for a manual or circuit diagram. A circuit would be most helpful but not essen-tial.

Ian Thomson,
80 Bungarribee Rd,
Blacktown NSW 2148,
Phone (02) 9621 2938
thomsi@start.com.au
orthomsi&Integral.com.au

Modern cars are only evolutionary

In the July 2000 "Publisher’s Letter" Mr Simpson talks about 42V car electrics. In the opening sentence he states, "Most people would agree that there have been radical changes in the design of automobiles in the last 15 years or so." I must disagree with this opinion, as quite frankly, at best, the adaptation of electronic fuel injection, computer controlled transmissions and the like are at best a refinement of a very old technology. Improvement, yes, radical change, I don’t think so.

It is too easy to get caught up in our own brilliance and forget that automobiles, as far as their general principal of operation goes, have not changed in over 100 years. We are still driving cars that employ a largely inefficient internal combustion engine, driving through some sort of transmission to either the front, back or all four wheels. This description equally applies to the first Model T Ford, or the latest Commodore. The biggest real difference between them is the styling.

We should not confuse evolution with revolution. The advent of safety features such as ABS brakes and air bags are welcome additions to the modern car; as is anything that can improve our chances of surviving a crash. These are evolutionary devices and do not change the way the car operates.

Many creature comforts rely on electronics such as central locking, climate control air-con, CD players, satellite navigation, DVD etc. Again, let’s not pat ourselves on the back too quickly. Most of these exist out-side of the motor car already. Fitting them into a vehicle hardly makes them a giant leap for mankind. They do not contribute to what the car’s main purpose is, and that is to propel the vehicle in the desired direction. They just make it more pleasant or safe while we’re driving.

You might think that I am against all this gadgetry. Not so. It’s just I wish we could make some real advances in the automobile, such as a genuine radical change to the method of propulsion, with large improvements in efficiency. The only changes between models that are obvious now are the restyling changes, which are nothing more than a new grille here and a new curve there. Right now cars are starting to get sharper, squarer shapes around the boot area and straighter glass lines. Didn’t we see this in the eighties?

Unfortunately even at the young age of 32 I probably won’t live to see the death of the internal combustion engine, although I hope I’m wrong. Personally I can’t wait for the flying cars out of the movie ‘Back to the Future 2’. Now that would be a radical change. However, I don’t think the oil companies want us to have that just yet!

Paul Campbell,
Arana Hills, Qld.

Who is in charge of the kingdom?

I would like to add my experience with Queensland’s Elec-trical Workers Board. Firstly, your previous correspondent was in no way being too harsh on this group whose primary interest is in self-perpetuation. My field of work is broadcast electronics where I have maintained high-power radio and television transmit-ters for over 20 years.

Here we regularly work with single and 3-phase mains oper-ated equipment where input powers in the 100s of kVA feeding DC supplies of 25kV at many amps are not uncommon. I am a trained professional and perform maintenance on this equipment with skill and care, where adherence to safety procedures are paramount and yet I fall into the same category; I am not permitted to install a new GPO in my own home or build a kit that delivers switched 240VAC.

To be honest I had given up trying to do anything about this. I’ve come to expect that lugs bolted to contactors glow cherry red when tightening the bolt is forgotten or that if you order a 10A 3-phase supply, it may be wired with single phase 3-core 2.5mm building wire where two reds and a black are Actives, the other black is Neutral and use either 1 or 2 greens as Earth. When I asked about sleeving, they said why? No wonder you give up after a while.

I’m unable to recall how often on a new installation a 3-phase blower motor runs backwards; we all know that swapping two phases will make the motor rotate correctly but why is it sup-plied in the wrong rotation?

I’ve no doubt there are excellent electricians out there, but I despise an organisation that allows the bad apples to remain and reject those who don’t do the apprenticeship but have suitable skills and at least a much better appreciation of AS3000. What really scares me nowadays is we are now letting these bad apples perform communications work and I’d be pretty sure that adherence to mandatory separations between mains and comms is frequently disregarded. I’m sure you all recall that GPOs used to be available with integral TV sockets until one day when an unsuspecting person was killed while attempting to rotate his aerial. These are illegal now and in effect was prior recog-nition that some electricians cannot be trusted to properly terminate and protect signal from mains cabling.

On my last approach to the Electrical Workers Board, I let them know my background and offered to undertake any courses they considered would raise my skill level to enable myself to be registered as an electrician. The response was "it really doesn’t matter what you do or don’t know, the only way in is through an apprenticeship." As I said at the start, their primary concern is to maintain a closed industry.

For similar reasons to the previous correspondent, please do not publish my name.

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