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Garage door opener

Discussion in 'Electronic Repair' started by Silver Surfer, Sep 29, 2006.

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  1. Need a schematic for the printed circuit board in my Craftsman garage door
    opener. Did lots of Googling. Found nothing. Learned that The Chamberlain
    Group makes the openers for Sears. Contacted them and asked for a
    schematic. They said the board is proprietary, and they won't even sell
    parts for it. Only complete boards for sale.

    Can anybody out there point me toward a schematic?
  2. Spamfree

    Spamfree Guest

    How old is the unit? I have a couple schematics - but - I think they're for
    "much" older units. On the other side of the coin - nothing like "customer
    service" - but then again "job security"........ take your pick!
  3. John

    John Guest

    Age and model number of the opener? Sears has sold a variety of them
    over time...
  4. Sjouke Burry

    Sjouke Burry Guest

    I have employed a garage opener for a wireless
    job as a 14 bit transmitter/receiver set.
    I have used google to find docs and application
    notes on the parr/serial/parr. chips on the boards.
    Also a scope can tell you much about the operation
    of the unit.
    In the end I used a serial/parr. shift register
    to decode the serial stream from the receiver.
    As it received a total of 42 bits, I used a
    comparator on about 15 of the steady state bits,
    to test for integrity of the data. If you have a
    pic of the transmitter unit,(post on a.b.s.electr,
    or you might delouse my email adress,figures in
    the first part,after @ no double letters)
    I might see if I recognise it, it had a rather
    stange shape.Also indicate what you want to do
    to(with) it.
  5. This opener is probably in the neighborhood of fifteen years old.
  6. This opener is about 15 years old. The number on the printed circuit board
    is 14PC366B. Will have to get out the ladder again to get the Craftsman
    model number. I'll get back with you.
  7. Just trying to fix this board. If the door operator goes up and down by
    depressing the switch I'll be happy. Don't care whether the remote works or
  8. Guest

    I've found that 70% of the people who say "It's proprietary" simply
    don't know.

    Chamberlain has some real technicians who can sometimes be reached if
    you ask a specific enough question, and I was once able to speak to one
    by getting technical enough about a safety defect. But I doubt they'll
    give you a schematic, and instead you'll have to trace out the pins
    from the processor (probably Zilog or Microchip) to the relays. Most
    of the failures tend to be from cracked solder joints (motor
    vibration), a bad motor capacitor, leaky electrolytic capacitors, burnt
    relay contacts (if you can't find new relays that fit, try substituting
    the overhead lamp relay for one of the motor relays), or shorted relay
    driver transistors and the diodes meant to protect them from relay coil
    back EMF. Usually the back EMF won't damage the processor or control
    circuitry. If your Sears/Chamberlain is like the one I bought in the
    early 1990s and has 2 circuit boards, I wouldn't be surprised if the
    pins that connect them together (like square wire wrap pins) have
    corroded. If your door will open but not close, check for the wires
    being broken right where they enter the optical receiver and sender
    boxes. Also, just becuase the indicator light for them shines steadily
    doesn't mean they're aligned well enough.
  9. Guest

    I'd check the remote circuit anyway since there's a trace from it with
    a logic signal to indicate when the remote has been activated. If it
    blips when you press the button, very likely the power circuitry is OK.
  10. me

    me Guest

    Quite often the problem is dirty contacts on the relay. Cleaning them with
    light emery paper usually has worked for me...
  11. You've given me some good ideas on things to check. Thanks for your
    interest in my problem.

    Some observations:

    The 110V incandescent bulb stays lit all the time.
    The board uses three Omron 24V relays to do its thing. One of them is an
    open type, and its contacts are in good shape.
    On the bench I can't hear any relays operate when shorting the up/down
    button terminals.
    I don't see any suspicious looking solder joints.
    Don't see any burned up or darkened components.
    Don't see any cracked or melted circuit board traces.
    This opener has no optical safety sensors.
    There is a 16-pin integrated circuit on the board made by TI. Cannot find
    the number anywhere on the Web. Called TI. They could not identify it
    either and concluded that it was an ASIC.

    More questions:

    What effect on the circuitry does the optical speed sensor on the motor
    shaft have? Does its output need faked with the main board on the bench for
    How do the up and down force limiters work?
  12. Guest

    The revolution counter board (optical speed sensor) is a timing
    circuit. The pulses are sent from the counter board to the main logic
    board at a uniform rate. So when the door meets an obstruction the
    motor slows down, which changes the timing of the pulses & this tells
    the opener to stop if the door while opening or stop & reverse while

    So the force limiters set how much the motor has to slow down before
    the opener will react to the change in the timing.

    If the counter board is bad or not hooked up the opener will run for
    exactly 4" in & then stop or stop & reverse back for 4". So for bench
    testing the relays should still pull in even though the counter board
    isn't connected.

    There is 3 relays on the board, one is for open, one is for close, &
    the third is for the light. As soon as the opener is plugged in the
    light should come on & then time out & shut off. If it stays on all the
    time it sounds like the light relay contacts have fused together. If
    the open & close relays won't pull in, then either the coils in the
    relays are bad, or they are getting power. Check for incoming power to
    the relays & trace backwards if they aren't getting power.

  13. You've given me a wealth of knowledge on this subject. I am grateful.
    Heading for the bench . . .
  14. Mr. Doordoc,

    The light relay contacts are not welded. The relay simply picks up as soon
    as power is applied and stays picked up from that point.

    The up and down relays will operate if I momentarily fake a signal to the
    base of the transistors that drive them.

    Shorting the up/down switch terminals makes nothing happen whatsoever.

    Just how exotic is that proprietary IC on this board, the 16-pin one? There
    is another proprietary chip that has only 8 pins. Not sure of its function.

    I'm thinking that the IC is bad or else a critical input it needs is not
    present. What do you think?
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