Design vs manufacture vs test

[evingar]

Interesting points Michael.

WRT the boiler, the purchase price of the boiler is to a certain extent irrelevant to the board price. The cost to the "punter" of a new boiler install would be considerably more expensive than just the boiler after the costs of getting a Gas Safe installer to fit it. The cost of fitting a new board is trivial by comparison.

On the face of it, there is an opportunity for a lucrative repair activity here. You would have to construct a rig that aped the functions of the boiler - I wouldn't fancy using a live installation to repair a controller PCB .

.. Having said all that, I'm sure the manufacturers have got that all "sewn up" via their agents and "custom" and programmed components on the controller. Maybe someone here knows this industry and can advise ?

[MichaelR]

Here we go again let us have a go at the robbing manufacturers or dealers or service agents . "It is day light robbery to sell a new boiler for £800 and charge me £300 to repair it".

I cannot accept these generalisations , Companies have to make money that is how they pay employees. In this country you have to charge labour at least £12 an hour to make a very small living.

Companies are not going to charge you the cost of a service component they have to charge you more because it may be stuck on their shelves for years waiting to be bought.Dare I mention that word obsolete, the masses decide when something is going obsolete when they decide to stop buying it.

Most companies today have to gamble on what people will buy and what they will pay. You cannot get that wrong too many times before you will go bust.

Mike

[davegsm82]

I currently work in industry, for a company who make industrial sized PSU's for trains, planes and lasers.

I have a couple of examples of things i've found which have caused major problems for production, putting stops on lines etc.

Situation 1, I'm the primary tester on a 8KW, 4 Channel 27,000V Laser PSU. I had a major shock a while ago (not in the literal sense, i'd be dead if that happened!) which was caused because some so called 'Engineer' decided to chop out about £1 of components (an op-amp, Opto-coupler and some passives) for no apparent reason. However, they were still physically fitted to the card, meaning nothing was actually saved. The Parts in question were meant to detect if the isolated 5V rail for the voltage feedback fails, meaning the boost controller goes out of control, the boost controller is meant to limit to 830V, this is from a rectified 3phase.

The 'Engineers' simply chopped out the code in the micro, saying that if the boost goes out of control they'd be able to detect it on the normal voltage monitoring input, and that they had put in a 1 Second delay in the processor before it shuts down.

One fateful wednesday, I powered up a repair unit for initial testing, connected to 3 phase at 415v. It was idling quite happily for about 10 minutes while I took measurements, until... BOOM!!!... :-O

I felt something hit my face, then realised I couldn't hear anything, then felt a trickle of blood on my cheek.

What had happened was what I've described, the boost lost its isolated feedback sense, decided that the Boost rail was too low voltage and kept ramping up until it reached 1000V, which is the breakdown voltage of the string of 5x 200V clamping zeners, designed for transients.

The Zeners (the size of a 1N5408) subsequently exploded into thousands of fragments, of varying sizes, some dust and some the size of half of the body. The PCB can be seen in the attached picture.

One of the fragments hit me and put a cut on my cheek, I also had to go to the doc's because my hearing didn't return as quickly as it should have. Luckily there was no lasting damage.

I have that section of PCB cut out and am thinking of imbedding it in epoxy or plastic as a coaster.

Previously to this, I was a lab tech, I was asked to design and build the drive gear for a Multi-voltage phase-swap 30KW DC-DC converter, running a capacitor blocked transformer. One of the engineers had already designed the high power side, I just needed to make the stuff to drive the 4x IGBT's.

Initially they'd tried using a processor, a modern QFPA TRI-CORE thing, running at 3.3v. As soon as they applied any power to the high voltage stuff, the RF generated would either obliterate the core or crash it long enough to latch the high power stuff on or off and make some rather large explosions.

The circuit I made consisted entirely of a 555, LM324 and a shedload of CMOS logic. Although complicated, the system was extremely elegant and worked flawlessly running the converter for days without any problems, Demonstrating the concept to the company big-wigs.

Last month I found all my hard work in the bin in the lab, they'd gone back to a processor, blown all the IGBT's, then put the converter to one side essentially shelving the project. I retrieved my PCB's from the bin (all still intact) and brought them home.

Logic, simply isn't 'Logical' for use in industry any more, it all has to be unreliable little black boxes, so called 'Hi-Tech'. In their quest to make the processor work, they blew up over £1000 worth of power transistors, my hardware solution never blew a single one

Ah well, their problem now, not mine.

Sorry for the Essay

Dave.

[Michael Maurice]

In some ways Mike you are correct, another engineer told me that for a component in a product, there are three prices, the factory price, the dealer price and the retail price.

Dont forget that factory prices are low because they buy and use in bulk. Components such as CRT's or screens or engines are delivered to the production line on crates containing multiples of that product.

For spares, that one unit needs to be boxed, then distributed then possibly left on the shelf waiting for someone to buy it.

As an independent service engineer, I have components that have sat in the draw or spares box for months or even years. Some especially those used in CRT sets will probably never be used. so am I ripping people off by charging £2 for a resistor or £3 for a capacitor, that part has been bought and paid for long before it goes in the customers set.

BUT

The general public don't see it that way, they dont understand this concept all they know is product cost £xxx spare part cost 1/3 £xxx why is it so expensive.

[MichaelR]

All you have just posted is spot on Michael.

I do not need to tell you that you cannot overcharge for your services. Most of the General Public are not self employed and really do not understand the running of a business.

Everything costs money

Mike

[Michael Maurice]

The thread started off as a Vintage Technology design thread but has some how drifted into modern technology design, and yes I'm partially to blame for this.

Can we please now return to to design problems of vintage technology,? In other words stay on topic!