Circuit Boards

[Andrew]

The absolute manifold pressure sensor on my Astra F had three connections, +5V supply, ground and analogue return. The connector did not have gold-flashed pins which under the bonnet of a car is a silly cost saving exercise. Ditto the rad temp sensor.

I suspect a lot of people are paying out large sums to have circuit boards in cars replaced, when in many cases simply pulling the connector off and replacing, wipes the surface corrosion off the pins and cures the fault anyway.

Most garage grease monkeys don't appreciate the difference between something with a 12V supply and another sensor with a +5 logic supply. Spraying WD40 all over the connector pins is the sort of dumb thing they try.

All the backplane connectors in my computer, sitting in my nice warm dry 'office' are gold-flashed.

[Andrew]

Neighbours Renault Megane needed a complete new instrument panel when it went blank. £400 just for the part. It might have been something simple like a diode or voltage regulator but no-one has the time or skills to investigate.

[tabbypurr]

That's to be expected with connection problems one gets in high vibration environments. It's inconclusive.

NT

[Dave Plowman (News)]

Gold flashed connectors ain't that common on cars. Some other form of decent plating, yes. Connectors usually packed with a special grease to help prevent corrosion. Many modern connectors are also pretty splash proof too - unlike once.

Quite.

Car electrics seem to be something the average mechanic or fitter has no wish to learn about. And even some specialist auto electricians are little more than bodgers.

Yehbut they can be dealing with high frequency very low current signals. Not something you usually see from an engine etc sensor.

[Dave Plowman (News)]

Just the same with the PCB on my Viessmann boiler. Had a number of on board fuses of the solder in type, one of which had blown due to water getting on the spark generator. Nothing in the manual about checking or replacing those fuses, and well beyond a service monkey. Who would simply replace the board at fast cost. Instead of soldering in a new 10p fuse.

[DerbyBorn]

Possibly a time served Plumber. Good at joining pipes.

[rick]

Hope it fairs better than my Baxi Barcelona .... gas maintenance have changed 5 boards out in past 3 weeks ... even changed both boards at same time on one visit.

[Mark]

iv?e had a Baxi Barcelona in a rented house for 13 years and only needed to repair it once. ( christ what have said touches wood, lucky rabbits foot) preventive maintenance, change spark electrode every year and check combustion chamber seals. "gas maintenance" are mostly plumbers who only seem to know how to change a circuit board

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[Tim+]

Perhaps they need to find out what's *actually* wrong?

We had a similar (though not as extreme) problem with our boiler which turned out to be due to a badly sited automatic bleed valve above the boiler leaking water into the boiler. The "engineer" completely failed to spot this.

Tim

[Chris Bartram]

Yes. I had the misfortune to have a Volvo 480ES, which had a CEM (Central Electronic Module), the equivalent of a convenience/body control ECU in today's cars. A nightmare, madly built, unreliable. Mind, that applied to the body and mechanics too, not just the electronics.

[Dave Plowman (News)]

That was the problem with my Viessmann. A hose at the top of the boiler - between the heat exchanger and copper pipework - split, and soaked the spark unit and gas valve. But was pretty obvious. ;-)

The exploded view of the boiler in the installation booklet didn't show this hose - just a solid pipe - so it was presumably a mod on later boilers, perhaps to reduce noise.

I've just got rid of my '97 BMW and that never had a coolant system hose replaced in its life, so it's possible to make such things last more than the few years this one did. Or to have some form of shield to deflect water away from electrical bits.

[Dave Plowman (News)]

Pretty well the first EFI car in the UK was the Rover Vitesse. Nominally a Lucas system, but based on Bosch and uses lots of Bosch parts. The ECU is pure Lucas - and actually pretty reliable in terms of failing. The main snag with the system was production variations. Even when new, some cars performed very much better than others.

[DerbyBorn]

We need "Boiler Technicians" Not "Plumbers" or "Gas Fitters". They need to understand the control logic and the interlocks.

[Mark]

They are reasonably easy to fault find, start up goes flow sensor ok > fan running ok > spark ign on ok > gas valve opens > flame detected ok: it working.

Lockouts, will not attempt to start flow temp thermostat fan thermostat safety thermostat condenser trap full

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[The Natural Philosopher]

trouble is, after all the training they can earn more fixing something more expensive

[DerbyBorn]

"Mark" wrote in news:npchdm$18k$ [e-mail]:

.....but usually - It isn't working, I'll change the PCB!

[Andrew]

I got rid of my 1997/8 Astra F estate last year and it never let me down after 13 years of motoring.

Apart from replacing both front wishbones when the rubber/metal joints failed (design flaw) that was it. Nothing ever failed and left me stranded. Had all its original hoses and drive belt for the alternator, PS and air-con. The ford garage I bought it from in 2003 put new disks and pads on and new tyres all round. The rears still had

6 mm of tread when I sold it after 40,000 miles.

[john430]

replying to DerbyBorn, john430 wrote: automotive parts for circuit boards are of much higher quality than those used in the washing machines etc. also most of the electrical designs used in home appliances are really garbage designs as if they are made by amateurs whereas those in cars are very good designs.

[Dave Plowman (News)]

Think what you actually mean is PCBs in cheap domestic products are likely to be cheap too. Buy a quality make and you're more likely to get quality everywhere.

Car stuff is made to a quality to survive the required time with minimal failures within warranty. No different from domestic stuff. If it is generally better quality, that's because a car is a far more hostile environment than a house.

But to say all car PCBs are perfect is nonsense.

[Mark]

You only have to look online to see the number of relativity young cars being sold for peanuts because of ECU/electronic problems that result in a nun runner or MOT failure

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