Total newbie

[irpacaus]

Hi Guys and Girls

Hi. I’m David and interested in electronics. Looking to do some simple projects for my car. But interested in looking at an ignition timing Mosul to under stand it’s layout.

I have opened up an electronic ignition module from a ford v8 from the early nineties and I want to draw out the circuit diagram. But I am having awful trouble identifying some of the parts on the board.

There appears to be a lot of flat black squares on the board. It appears there is a trace coming in each side and parallel to each other and the a black square painted over the top. When you look close in real life you can see the traces and nothing else. They don’t seem to touch at all.

Also a bunch of other components on the board I can’t work out. Googled to my hearts content but nothing.

The board is a single layer with traces running over the top of each other with a non conduction layer applied between of they are bridged with fly wires.

Your thoughts

Thanks

David


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[Mr. Scram]

Hi David, welcome to the forums! It looks like you picked a good one to start with. I see lots of things that aren't quite your run of the mill PCB.

It looks like it might be a ceramic PCB, rather than the more familiar fibreglass. You don't see those often, though Dave had one in his neurostimulator teardown. There also seem to be a few what look to be bare ICs, in the golden squares down the bottom, with bond wires coming off them. It also appears there are some traces going over other traces on the same side of the board, which is a technology I've not seen before. As for your black squares, I guess they might be carbon printed resistors.

If I were to hazard a guess, this seems to be a board built with high reliability in mind and is probably resistant to high temperatures.

[Ian.M]

The bare dies look like power Darlington transistors.  Of the five lowest pins on the header on the right, it looks like the center one goes to all their emitters, with the remaining four pins to their individual collectors.  Base drive appears to come via a resistor network from the large Motorola IC.

[irpacaus]

Mr Scram

Thanks for the reply. Yeah it is a bit of a doozy. It is definitely built for hi temp applications under the bonnet of the car.

They 4 bare items at the bottom are the coil pack drivers for the ignition coils.

Carbon printed resistors. Nice I will look at that. I guess I will have to throw a meter in it to see what the values are.

The whole board is covered with this clear jelly material which need to be removed. Not sure if you can buy this stuff to re-apply it afterwards.

Thanks

David


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[Mr. Scram]

The clear material would be conformal coating, which is meant to protect the board from moisture ingress. Typically, it's hard, but it sounds you may have a "reenterable" variant that allows rework or adjustments after applying it. Dave found some of the latter in his teardown of a parachute AAD, another high reliability device, though that might be slightly different yet from what you have.

[irpacaus]

Ian

Thanks for the name of the power transistors. That is useful.

David


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[Leuven]

I had opened up a Bosch ABS module which was manufactured in exactly the same manner. I knew exactly what was wrong, couple wire bonds lifted form their pads but for the life of me I couldn't solder them back on. They were originally spot welded. Between trying to scrape that muck off and my soldering attempt, I managed to wreck the board.

[David Hess]

The flat black squares are thick film resistors printed onto the substrate just like the various traces and the blue insulator.  Thick film printed "hybrids" are common in high reliability applications.

[irpacaus]

David. Thanks



Is this likely a 5v BL8530-501 step up dc dc convertor. Can’t find anything on the net with the codes printed on it

Thanks

Dave


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