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Identifying a chip

Discussion in 'Troubleshooting and Repair' started by Robbie Hegarty, Feb 4, 2018.

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  1. Robbie Hegarty

    Robbie Hegarty

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    Feb 4, 2018
    Hi folks

    I'm trying to repair an old controller board for a metal folding machine. You can see from the picture that the chip at location IC3 has a hole. Unfortunately, the chip numbers have been scratched off all the chips and the manufacturer will not identify it for me.

    Could anyone help identify the chip or ever suggest where I could get a replacement board?


    Board1.jpg

    Board2.jpg
     
    Last edited by a moderator: Feb 5, 2018
  2. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    My guess is that it's a standard but of glue logic.

    I'd be looking for a 20 pin chip with parallel inputs or outputs on pins 12 thru 19. It might help if we can see the other side of the board.

    Edit: it might also be something like a 74HC373 that has interspersed inputs and outputs on these pins...
     
    Last edited: Feb 4, 2018
  3. Robbie Hegarty

    Robbie Hegarty

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    Feb 4, 2018
    Thanks Steve

    I don't have the board at the minute, and I didn't take any pictures of the back of it. But I'll try to get one sent to me and I'll post it up here.

    Robbie
     
  4. Bluejets

    Bluejets

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    I'd be surprised if there is not other damage as well with a blow up like that.
     
  5. (*steve*)

    (*steve*) ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd Moderator

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    Yeah. It's not obvious that this chip is an input or an output. Was there a power supply fault?
     
  6. Robbie Hegarty

    Robbie Hegarty

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    Feb 4, 2018
    There’s no other obvious problem on the board, but I won’t know for definite until I get this one sorted.

    The power comes via the motherboards ISA slot. There doesn’t seem to be problems with the power supply. I have a feeling I caused a short by letting the underside of the card touch the chassis of the PC.
     
  7. hevans1944

    hevans1944 Hop - AC8NS

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    That's really unfortunate, but given the secretive practices of the board manufacturer, your only alternative may be to send the board back to them for repair. Have you made any inquiries with this company to find out how much they would charge to repair or replace this interface control board?

    This board is no doubt integrally mated with custom application software running on the PC in which the board is installed. It may be necessary to have available the entire PC, as well as the metal folding machine, to properly test and verify the interface board works after the repair. In other words, this may require one or more on-site visits before a successful completion of the repair. You probably don't have access to the software source code either, which moves this entire project into the "character building" realm requiring extensive reverse engineering. Jubilee Electronics is fully aware of this conundrum of course. A cost-effective repair may not be possible.
     
  8. Robbie Hegarty

    Robbie Hegarty

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    Feb 4, 2018
    Thanks for that heavans1944

    The board, as you suggest, is mated with custom software and the folding machine. It belongs to a friend of a friend, who initially paid around £50,000 for it. It started developing a fault where the software would cut the wrong size sheets, and not bend at all.

    I'm actually a programming lecturer who often gets asked to look at hardware issues for friends. The PC that the card was in was really ancient and very sluggish in response time. So I wanted to rule out the PC as being the problem by replacing it with a newer one. I still needed a motherboard with an ISA slot so I managed to build a computer with old parts but that were newer than the existing one.

    I built the machine, moved the ISA board over to it as well as the old drive and tested it. The whole system was working perfect - doing everything it had been doing when first bought. Delighted, I wanted to copy the software from the old disk to a newer one. I still had the PC case open while I was doing the tests and hadn't screwed the ISA board to the PC chassis. It drooped a bit and that's when I think it shorted.

    There's no way of going back to the original company. I communicated through a lot of emails. They only want to sell a new system.

    Robbie
     
  9. Ian

    Ian Administrator

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    Aug 23, 2006
    This is a bit of a stab in the dark, but could it be from the COP942C-XXX/N or COP942CH-XXX/N range from National Semiconductor?

    I've attached the datasheet and a pin out, to see if that helps:

    Capture.PNG
     

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  10. Robbie Hegarty

    Robbie Hegarty

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    Feb 4, 2018
    Thanks Ian

    Amazing help on here!
     
  11. Ian

    Ian Administrator

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    I'm glad you like it here :).

    I'd wait to see what the other guys think first, as this is a bit of a wild guess and I could easily be incorrect!

    edit: I should clarify that I looked up that part number based off the logo and markings, rather than identifiable pin-outs.
     
    Last edited: Feb 5, 2018
  12. kellys_eye

    kellys_eye

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    Looks like Vcc is definitely pin 20 on the damaged chip so doesn't match the datasheet shown....

    I'd suspect something simple like a 373 or 244/245. If we can identify the processor it would be simple to discover if the chip is buffering/tri-stating any data lines (which I suspect will be the case).

    The chip appears to be socketed - can you remove it to see where the tracks go under? The 'bottom row' of pins run 'somewhere' - if it is to the board edge connector then knowing which pins they connect to will reveal a lot!
     
    Last edited: Feb 5, 2018
    Ian likes this.
  13. kellys_eye

    kellys_eye

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    Additionally - the CPU is a 'rare' shrink 64 DIP package limiting the possibilities and with pin 26 being a ground (?) i.e. other end of C6 that appears to be to Vcc of the dud IC, then some investigating into the CPU type might also help...?
     
  14. Robbie Hegarty

    Robbie Hegarty

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    Feb 4, 2018
    Hi folks

    Sorry it took so long. I've just managed to get the board back. The owner had it with a local electronics guy who was apparently sick for a while.

    I've taken a couple of pictures of the back of the board as requested.

    Thanks again for all your help?
    Board3.JPG Board4.JPG
     
  15. kellys_eye

    kellys_eye

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    It's either an 74LS241 or LS244 device. Most likely the 244.

    Is it socketed? If not, fit one then get one of each device and try it - you will come to no harm by fitting the 'wrong one' (as the only difference is a chip select line and some inversion) but one of them WILL work.

    Since it's taking the output from IC1 which itself is connected to the databus (A1-A8 on the edge connector) it can only be buffering the data lines therefore an octal buffer and, as with most such devices, tri-state.
     
    Last edited: Feb 28, 2018
    Ian likes this.
  16. Robbie Hegarty

    Robbie Hegarty

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    Feb 4, 2018
    Kellys_eye, thanks so much for that.

    It is socketed, so I’ll order both those chips tomorrow. Any recommendation on where to buy?
     
  17. kellys_eye

    kellys_eye

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    Where to buy? Somewhere reliable is all - Farnell is who I usually use.
     
  18. Robbie Hegarty

    Robbie Hegarty

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    Feb 4, 2018
    I've ordered them from Farnell now. I'll let you know how it goes what they arrive and I try them in the board.
     
  19. Robbie Hegarty

    Robbie Hegarty

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    Feb 4, 2018
    UPDATE

    I've tried both of the chips that were recommended and neither work. I've attached a couple of pics showing the card with one of the chips.

    When I say that neither work, the software reports the following:

    "Interface card failed to initialise"

    Interestingly, it shows the same error if the card is not present at all.

    Is it safe to say that other damage must have occurred on the board when the original chip failed?

    Any other suggestions on how I could proceed would be very welcome. Or if anyone knows where I could get a replacement board that would also be appreciated.
    .
    .
    .
    .
    .
    .
    . Board6.JPG Board55.JPG
     
  20. davenn

    davenn Moderator

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    Sep 5, 2009
    highly likely .... a chip doesn't blow like that unless something significant happened
     
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