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

Hi William,

yes, yesterday I once pulled the chip (unfortunately, I already pushed it in again). It sayed something like a AA, MALAY 963. I did a reverse lookup on Google, just to find out nothing about it. I think the simply is kind of a serial number or so. But is there any site where I could do a reverse lookup of such numbers just to find out the exact type of the microcontroller? If so, I would dare to pull the chip again.

No, the filter capacitor is not shorted, I just measured it. Hmmm.

Yes, it´s a "L7805C-V". Well, I didn´t yet supply any 220V AC voltage to the board in an offline test yet. I.e. after the garage door opener failed, I didn´t dare yet to put on 220V~ again. Hmmm, is there any valid means to test this "L7805C-V" offline with a 12V DC power source?

It definitely is a 5v one!

Unfortunately, I don´t have a scope, only a meter.

Yes, I know. By the way, might he 16-pin IC a I2C maybe? If so, which ones were commonly used to control an Intel 8748/8749 ?

Thanks, Joachim

On Fri, 09 Feb 2007 13:23:15 +0100, Joachim Wunder Has Frothed:

that

Just replace it, they're cheap. Or you could check it in circuit powered up for 5+ volts between the middle and right pins.

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COOSN-266-06-25794

I just measured the pins of the 16-pin IC with a logic tester: Pin 14 always stays HIGH at +5V with >2 MHz. Does that point me to a Philips I2C with a SCL line at Pin 14? If so, which I2C might that be?

Thanks, Joachim

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

On Fri, 09 Feb 2007 02:10:40 +0100, Joachim Wunder put finger to keyboard and composed:

It could also be an 8751, although the location of the crystal would suggest a 48 or 49. You should be able to narrow down the likely contenders for the uC by determining which pins are Vcc (40?), Vdd (26?), Ground (20?), crystal (2 & 3?), reset (is there a resistor and capacitor at pin 4?).

FWIW, I have some 8749 chips in my junk box. I also have a device programmer that can handle them. If you are lucky, and if the uC has dead ports but accessible EPROM, and if the security bit (?) has not been set, then I may be able to copy it for you. In the past I've been able to recover code from bad ROM versions of Intel uCs and replace them with the EPROM versions.

BTW, I'm in Australia.

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.

On Fri, 09 Feb 2007 13:37:10 +0100, Joachim Wunder put finger to keyboard and composed:

There appear to be 8 or so interconnect pins at the RHS of the 16-pin IC. Can you trace them to the uC's pins? Do they go to the data bus, ie pins 12 through 19? Which pins are power and ground? What is the IC to the right of the relays? Which chip/component drives the relay coils?

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.

Tried these guys?

"Arfa Daily" wrote in news:Fl6zh.765$ snipped-for-privacy@newsfe1-win.ntli.net:

Yes. Does the motor work? Do the relays switch? Are all the Diodes functional? What causes you to suspect the IC's? Are you just whistling in the dark because the voltage regulator that normally gets hot has discolored the circuit board it sits under? Without actual troubleshooting you are not going to get anywhere...

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No, I didn´t tried them yet. But I have done some good progress today: After a whole bunch of further phone calls I was now finally able to find out the manufacturer of the PCB. It´s a very small company in Saar/Northern Germany. They are not on the Web, so you simply can´t find them there, unfortunately. But the company who installed the garage door opener back in 1990 had a deeper look into their archive to find out this small company for me, again. Thanks God. Well, even this company is located in Northern Germany but not presented on the Web at all. So, life sometimes really sucks, I know.

Well, unfortunately, the techie himself who designed the PCB wasn´t in today, but another tech person of the same company told me that they MIGHT have some spare PCB still in stock. Thanks God. But this is only an assumption and cannot be clarified before the upcoming Monday. So, I will keep you all posted here. :) And, moreover, the techie whom I had on the phone today even told me that all employees are definitely not authorized to hand out any circuitry plans or specs/types of the microcontroller and the accompanying IC. Holy cow.... anyway... there´s some hope the next Monday. I´ll report back and keep you all posted with an update then.

In the meantime.. thank you ALL so much for your tremendous support!

For the rest of the reponses from all of you, I will answer one after the other post. So, please be patient with me. I´m just sitting here with a logical test device to find out any more information. Joachim

I just uploaded seperate larger pics of the front and back side of the PCB:

front side:

back side:

I am sorry to not have done that any earlier. On weekends I now have a little more time to take better pics and start any systematical diagnostic tests.

As far as I can see Pins 12, 13 and 14 of the microcontroller are connected to the interconnect pins at the RHS of the 16-pin IC.

Pin 8 is V_SS (GND) and Pin 16 is V_DD (+5V) as far as I measured on the 16-pin IC.

That´s a PHILIPS CNY17-4 Optocoupler.

That´s actually a BC237B transistor each. They are hidden below the piggyback PCB, unfortunately.

Thanks Joachim

I just measured: Pin 40 is Vcc, Pin 26 is Vdd, Pin 20 is Ground, Pins

2 & 3 are crystal. At Pin 3 there is a 22 picofarad capacity as well. Between Pins 4 & 5 is a resistor with 10kOhms.

Thanks for your very friendly offer. I just recovered my old Eprom Burner from 1992 yesterday night. It´s a German model from

with a separate ISA card, DOS software and an external adapter which plugs right into the ISA card with a fat ribbon cable. Unfortunately, right now I only have the 32 pin textool external adapter which is capable to mainly handly only EPROMs at sizes up to 2 MByte. Anyway, I just contacted ELV Germany and asked them whether they still have the external adapter with 40 pin textool socket. This adapter is explicitely described to be able to handle 8748/49 µCs in the manual of the burner. And even the old DOS software is able to handle these

8748/49 µCs. Thus, I will see what ELV will respond. I then may get back to your friendly offer. :) Thanks a mil.

Oh, well. I always order most of my satellite dish from Australia. Thus, distance shouldn´t be an issue for me. *g*

Kind regards Joachim

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 that´s just a guess, you´re right.

Well, no reason for me to be afraid anymore: I already applied 230V AC to the large pins 3 & 4 on the backside of the PCB (counted from left to right on

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.

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. That´s actually my fear that the transistor and/or the 16-pin IC could have been damaged.

PCB front side:

PCB back side:

Right. So, my apologies that I didn´t 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 shouldn´t 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

On Sun, 11 Feb 2007 01:44:42 +0100, Joachim Wunder put finger to keyboard and composed:

I think you're right about the uC being an 8748 or 8749. I'd confirm that the reset pin (4) is not being held low by a shorted reset cap, especially if it is a tantalum type. BTW, pin 5 is connected to Vcc, so the 10K resistor is essentially a pullup.

I have an old (1991?) Sunshine Expro-60 with an ISA controller card in an old 486 box.

That's a big surprise. I would have thought these dishes were cheaper in Europe where satellite TV is much more widespread.

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.

On Sun, 11 Feb 2007 01:03:22 +0100, Joachim Wunder put finger to keyboard and composed:

AFAICT, the 16-pin IC, if the piggyback PCB faithfully mimics the pinout, has at least three outputs at pins 1,2,3, each of which drives the base of a relay driver transistor. Each pin has a pullup resistor to Vcc, so I suspect that the outputs may be open collector.

Since pins 10,11,12,13 of the IC are connected to the uC's data bus, I suspect that they may be inputs. If so, then I believe that these inputs would need to be latched. The fact that there is a "VOH" on the body of the chip suggests that it might be programmed, in which case it could be a PAL.

- Franc Zabkar

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Please remove one 'i' from my address when replying by email.

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

That´s what I was convinced too up to the day when the bulb was blown for the first time. Well, I´ll tell you something, I have one sheet of paper which came with the PCB, but which only describes part of the external connectors (i.e. actually only the ones which interface to the motor on the backside of the PCB). The "funny" thing about is that this sheet shows a very rough outline of the PCB´s external connectors and mentions a fuse which is said to be there in the (N)eutral line of the PCB´s power supply. Ha! I would be glad if there was that fuse which is rated at 1A F(link). "F(link)" in German means with very quick response time. And what do I see when I look at the backside of the PCB? Ha! The manufacturer has simply left out the fuse and has soldered a piece of wire instead of the fuse holder. Well done. :(

That´s not easy to do, ´cause I have no documentation of what signals the RHS large pins on the frontside of the PCB wait for. So, putting the PCB into thinking that it´s installed is not (yet) possible for me. I only know that the external remote control receiver is connected to two of these pins. Moreover, two external limit switches are connected to the other 4 pins. I first would have to find out more details measureing the switches out in the garage.

Again, thanks for your kind support. Joachim

Fuse links don't need to be actual fuses that you recognize, they can be special wire used, what looks like a resistor on the board or simply a small foil path that is 2 half-moons with a small link of foil between them..

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