"Joachim Wunder" wrote in message
...
On Fri, 09 Feb 2007 03:15:46 GMT, James Sweet
wrote:
Joachim Wunder wrote:
Hi there,
I have a garage door opener named "Liftboy SMD 3200" which was
installed into my garage back in 1990 (in Germany). I couldnīt get any
information about this garage door opener on the net. The motor
control PCB of it just failed this week. I suspect either any capacity
or the voltage regulator to be the culprit. Does anyone know the
manufacturer of the PCB shown under
http://img255.imageshack.us/img255/9023/cimg0094aq6.jpg ?
Unfortunately, the 40-pin PICīs type isnīt readable under the sticker
at all īcause its surface seems to have been scratched off under the
sticker by the manufacturer of the PCB. Yagh. Which PIC is it supposed
to be? There is a Quartz which reads "4.000 SUNNY 7624".
Moreover, the same applies to the 16-pin IC: Itīs surface seems to
have been treated by the manufacturer of the PCB, i.e. the exact type
has been completely scratched off on purpose as well. 
Is there any
way to find out which IC it might be?
Please advise.
TIA,
Joachim
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 ?? 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. 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
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 ??
Arfa