Well, I thought it could be an A/D D/A converter from Philips maybe
(like a PCF8591, for example). Or an I/O expander. But that´s just a
guess, you´re right.
Well, no reason for me to be afraid anymore: I already applied 230V AC
to the large pins 3 & 4 on the backside of the PCB (counted from left
to right on
http://img187.imageshack.us/img187/1555/cimg0084qg6.jpg).
Result: The voltage regulator is definitely not defective at all. I
can read a correct output of +5V between the right pin and the center
pin of it.
Well, today I again tracked down in the garage the path where the bulb
was actually connected to: When you look at the backside of the PCB,
PE is connected to the large pins 1 and 2, N(eutral) is connected to
large pins 3 and 8, P(hase) is connected to the large pin 4. The bulb
itself was connected to the large pins 7 (P) and 8 (N), that means
that the current for the bulb is actually switched by the most left
relais when you look at the frontside of the PCB. In consequence, a
shorttime short circuit of the bulb might have sent a current peak via
the most left relais to its +12V control input. The relais itself is
triggered with +12V with this voltage to be switched to the relais via
a BC237B transistor (NPN). As far as I can see from the backside of
the PCB, the transistor itself is controlled by the still unknown
16-pin IC. That´s actually my fear that the transistor and/or the
16-pin IC could have been damaged.
PCB front side:
http://img184.imageshack.us/img184/3231/cimg0083kj3.jpg
PCB back side:
http://img187.imageshack.us/img187/1555/cimg0084qg6.jpg
Right. So, my apologies that I didn´t had enough time before the
weekend to take a deeper look into the door opener in the garage and
onto the PCB again in any more detail. I know I better shouldn´t have
started this thread before having myself more time to do a more
detailed description of the PCB and the way the bulb was connected to
it. Again, my apologies.
Thanks,
Joachim