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PCB of garage door opener failed: Which PIC is this?

Discussion in 'Electronic Repair' started by Joachim Wunder, Feb 8, 2007.

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  1. Hi there,

    I have a garage door opener named "Liftboy SMD 3200" which was
    installed into my garage back in 1990 (in Germany). I couldn´t 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 ?

    Unfortunately, the 40-pin PIC´s type isn´t readable under the sticker
    at all ´cause 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: It´s 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.

  2. ??
  3. Unfortunately not. I already phoned them up today. And, no, they are
    not the manufacturer of this Liftboy SMD 3200. Any other ideas are
    highly appreciated.
  4. Any other info on the labels? Country of origin?
  5. Arfa Daily

    Arfa Daily Guest

    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.

  6. No, unfortunately not. Well, on the backside of the PCB is printed
    "PRO6101-28" in one corner. That´s all. Well, the garage door opener
    was installed into my garage from a small company called "Schiel" from
    northern Germany. Well, they said that the manufacturer went bancrupt
    a couple of years ago and that they don´t have any spare parts or
    information about this product of mine no more. :(
    Well, and the garage door opener "Chamberlain" said to me that
    "Liftboy" might have been an US based manufacturer who went bancrupt a
    couple of years ago, but they were not sure about it. I called up
    Chamberlain not only in Germany but even in Illinois, US.
  7. Well, ok, cleaning the 16-pin IC´s pins will be easy, and I´ll 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 didn´t
    show any reactions no more. The 25W bulb is connected in parallel to
    the PCB´s power supply.
  8. David

    David Guest

    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?

  9. At this point I'd buy a whole new one from a reputable company but I know
    prices there are higher than here. It'll be a miracle if you can get any
    parts for this unless you can track down someone who used to install or
    repair them.
  10. Yes, I am aware of the fact that I would need a PIC programmer and a
    new 8748 or 8749 PIC (I´m still not sure which one it really is).
    Pretty good question where to still get such a component from, I
    know,... is there any equivalent PIC which offers the same pin
    assignment and code compatibility of a 8748/8749? I know, even I doubt
    that, but I better ask in this group before giving up.
    220V AC, as we have in Germany.
  11. Yes, I know, chances are low. Tomorrow I´ll try again at the small
    German company which installed it back in 1990.
  12. Hi!

    I think the large IC looks like an 8031/8051 microcontroller...these are a
    very popular, relatively low cost and highly available part. Are you sure
    the power supply is working correctly? Perhaps it suffered some damage or
    opened a fuse when the bulb blew.

    One of these is ROMless, but I don't remember which one. What does the
    little pushbutton on the board do?

  13. Sometimes they know a guy who knows a guy . . . . .

    In a company I worked at, we had 4 injection moulding machines of poor
    design and reliability which were made in Austria by a company that went
    bankrupt. It was a PITA keeping those suckers going. We had to reinforce
    various parts with welded bracing.

    The Swiss ones (design styling by Italians) we replaced them with were
    expensive but were a joy to work on and would take anything you could dish
    out. Watching them mould a 2 litre bowl every 4 seconds was almost
    frightening to see.
  14. Right. I will give it a last try.
    Hey, could you do me a favour please? What was the name of the company
    in Austria? That all rings a bell to me: Company "Schiel" in Germany
    still believes, that my garage door opener´s motor control PCB was
    made in Austria as well. And when I look at the backside of the PCB,
    oh man, the soldering.. like if a 5-year-old child would have done
    some work on it. Various parts with welded bracing as well. Ufff. I
    will need some real professional soldering work to get all of that
    crap corrected anyway.
    I see.. I am not yet decided, but may do so soon if that hunting for
    the manufacturer won´t come to an end soon.
  15. Well, if I recall it right, then the 8031/8051 microcontroller comes
    in plastic package and doesn´t has an EPROM memory like the 8748/8749,
    right? So, I tend more for my PIC to be one of 8748/8749, but correct
    me if I´m wrong.
    No fuse on the whole PCB unfortunately. And, yes, the power supply
    still outputs a stable 12V DC.
    The little pushbutton normally helps the installer to testdrive the
    garage door open and closed. That´s what I know for sure about this
  16. It was over 25 years ago. It might pop back into my head but I doubt it.
    However these companies had nothing to do with garage door openers.

    You could design and build your own replacement, or maybe you could buy and
    adapt the parts from a different model.
  17. James Sweet

    James Sweet Guest

    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.
  18. Hi!
    Hmmm...checking the Intel datasheet for the 803x/805x family shows that some
    of them (8051/8052/8751) do have onboard ROM program memory. At least one
    UV-eraseable version also exists.

    Any packaging could be possible, given how many different companies have
    produced these parts over the years. Intel mentions a "CERDIP" package in
    their datasheet, which I would take to mean "ceramic DIP".

    Another thought just occurred to me...and maybe it occurred to you as well.
    Did you pull the chip and check the bottom of it to see if there might be
    anything printed there?

  19. rebel

    rebel Guest

    Exactly what markings are on the ?TO220-ish device below the small PCB? If that
    is a 3-terminal reg, I'd be checking it out as well.
  20. Arfa Daily

    Arfa Daily Guest

    It seems to me that this is all getting a bit over-complicated. Why would a
    simple device like this even need a micro-controller ? Some years back, it
    was fairly common practice to put chips like this onto boards, that actually
    did nothing. Literally just there for show to make the item look worth the
    money that was being charged for it. Anyway, it seems that there is an
    obvious transformer, reccies, and a smoothing cap. Is that where you are
    measuring the 12v that you mentioned ? The very hot looking TO220 device
    next to the smoothing cap is 99% certain a standard 3 pin monolithic
    regulator IC, and I would guess that it's almost certainly a 5v one, so do
    you measure something like 12v, 0v, 5v on its pins ? If you do, do you have
    a 'scope ? Can you measure any clock activity at that crystal ? Beyond that,
    without a detailed knowledge of the functionality, and schematics, it's
    pretty much impossible to come up with a valid test strategy, that's likely
    to result in a repaired board.

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