Anonim

CLUB OF CAR FANS

Birth defect

“MAGIC” LANTERN

If the Samara coming in front of you unexpectedly, without giving a signal, decides to turn to the side, do not be indignant. It is possible that her taillight "died" …

Mikhail KOLODOCHKIN

When one of the taillights flashed once again at the editorial "nine", and the tried and tested method of manual therapy by means of a fist did not help, I had to resort to an autopsy. What was inside is shown in photo 1.

You do not need to know Ohm’s law to guess - this green contraption (it is also a flexible printed circuit board made of foil dacron) has already served its purpose, as its contact pads rubbed into holes. And it's less than a year …

It seems that the old people are right - everything was better before. On the “classic” of the seventies there were neither flexible printed circuit boards, nor problems with their failures. To understand why the introduction of new technologies led to a decrease in the reliability of an important lighting product, we decided to buy a brand new flashlight and mock it a little in laboratory conditions - to assess the resistance to current overloads, salt fog, etc.

The pedigree of the lantern is interesting - it was manufactured by DAAZ OJSC, and VAZ supplies the flexible printed circuit board for it, and the plug-in block is made at Peresvet Plant JSC (Kirzhach). Note that the coordination of technical documentation with the "center" is now absent - the manufacturer is his own boss. Let's see what comes of it.

The geometric dimensions of the board turned out to be normal, but one of the socket pads was thinner than the others by almost a millimeter. Nevertheless, the torch withstood electric shock withstood dignity. For half an hour a current of 12 A was passed along the tracks of the printed circuit board, and for another 10 seconds - as much as 24 A. There was no burnout and delamination - you can move on. Ahead - salt fog …

If in the "greenhouse conditions" the lantern was not capricious, then a week in the cell already greatly spoiled its character. A clean, workable product went into the fog (photo 2), but something spotty and whitish returned (photo 3). There was no doubt that the failure was brewing - it happened. The very first inclusion showed that contact with the mass disappeared.

The physics of the process is obvious - moisture has got on the plug-in connection, the contacts have oxidized, the transient resistance has increased, the temperature has increased, and then - failure. In our case, the connector failed, although the same thing could happen to any of the bulbs whose caps are pressed against the conductors of the printed circuit board.

What should a car owner do in such a situation? It would seem to pull off the shoe, wipe dirty contacts, and then put the shoe in place. All this is so, however, at your disposal no more than eight attempts … The thickness of the current-carrying track of the printed circuit board is only 0.05 mm, and therefore any mechanical impact for it is the same as an emery for a polished body. For comparison, photo 4 shows the contacts of a brand new board, and photo 5 shows the same contacts after five-fold articulation. Appearing scratches portend a quick demise.

Well, who is to blame? The expert opinion is unambiguous - lanterns of a similar design can work properly only in sealed conditions - without moisture, dirt, salt and other attributes of Russian reality. In general, as in foreign cars, in which it is clean and dry. And as long as drafts are walking in the skewed Samar bodies, it is best to get spare printed circuit boards - it is not by chance that they are sold in any car shop …

The most moody element of the lantern is a flexible printed circuit board made of foil dacron.