"Joachim Wunder" wrote in message
...
On Fri, 09 Feb 2007 22:12:53 GMT, "Arfa Daily"
wrote:
The IC will have custom firmware on it so you won't be able to replace
it. Chances are unless the regulator has failed in a short circuit and
caused the voltage to rise, the chips are probably fine. Check to see if
the filter capacitor is shorted, I recently repaired an old Volkswagen
ECU that had a shorted electrolytic capacitor filtering the 5V output,
resulting in a dead car.
No, the filter capacitor is not shorted, I just measured it. Hmmm.
As long ago as this was made, I2C was not a common bus scheme ( if it even
existed at all ) and in any case, what would want to be communicating over
such a bus in a simple door controller ??
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 thatīs just a
guess, youīre right.
The regulator can be checked out
of the board by applying any voltage over about 9v between the left pin (
+9 ) and the centre pin ( 0v ), and measuring the output for +5v between
the
right pin and the centre pin. This is with the writing towards you or
metal
tab away from you. However, you are never going to get to the bottom of
this
board's problems by being afraid of it.
Well, no reason for me to be afraid anymo 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/img187/1...mg0084qg6.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.
A bulb blowing across the primary of
the Tx, is highly unlikely to have done any damage to it, and even if it
had, what is going to be the problem ? An o/c primary winding ? No
problem,
the board just won't do anything. A s/c or shorted turns primary ? No
problem - it'll just blow the mains fuse, or smoke. No matter what, 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. Thatīs 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
doesn't work now anyway, and you have no clue why unless you put some
power
on, and take some readings. It could be something as simple as a bad power
supply circuit - one of the reccies, or the 5v regulator, or yes, the
tranny
even, but unless you build up the courage to put some power on and see
just
what's going on, you're never going to know. Anything we suggest at this
point, is really just useless conjecture, yes ??
Right. So, my apologies that I didnīt 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 shouldnīt 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
No problem, at least we know what's going on now. I still would be reluctant
to believe that the bulb is going to have done anything directly to the
board, evn if it is connected to it by way of being relay switched. The
relay contacts are electrically isolated from the coil by virtue of
substantial mechanical separation. Now that you've got as far as putting
power on the board, you should be able to look for relay drive activity, by
using the test button, or by fooling the board into thinking that it's
installed.
Arfa