PCB of garage door opener failed: Which PIC is this?
"Joachim Wunder" wrote in message
...
Judging by the amount of heat that has been pouring off that regulator,
and
discolouring the board above, the first thing that I would be doing is
removing that chip that says " VOH " on it from its socket and cleaning
the
pins. What exactly is the board doing wrong ? Assuming that device is a
PIC,
in general, they are very reliable.
Arfa
Well, ok, cleaning the 16-pin ICīs pins will be easy, and Iīll do so,
of course. Well, from my first investigations the 40-pin PIC is very
likely to be an Intel 8748 or 8749. Question now is what current PIC
is still compatible to this old-fashioned one.
The whole board should control the 220V~ motor of the garage door
opener, but nothing happens no more. The board behaves like dead.
Reason might be a 25W bulb which blew off just before the board didnīt
show any reactions no more. The 25W bulb is connected in parallel to
the PCBīs power supply.
If indeed this is a PIC or some other type of microcontroller, you cannot
just replace it. It has to be programmed with the original code. Good luck
acquiring that since most manufacturers set a bit in the device to prevent
reading the program stored within.
The failure of the 25 watt bulb may be a clue. A bulb can momentarily create
nearly a direct short when it fails. What voltage is this bulb? 220v or
something smaller?
David
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