have to replace an IC (Unmarked IC)

Discussion in 'General Electronics Chat' started by satya5536, Dec 5, 2015.

  1. satya5536

    Thread Starter New Member

    Dec 5, 2015
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    I have a 6channel home theater system,for which volume control buttons are not working.It may be the pblm with ic.I have to replace it but it doesnot contain any number on it.Please help.It is a 18 pin IC
     
  2. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    As you say, it has no numbers, likely to avoid making copies of the product.
    Likely it is custom made and a replacement can not be found.

    Bertus
     
  3. hp1729

    Well-Known Member

    Nov 23, 2015
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    You are stuck going back to the manufacturer or an authorized repair person for the part. You could trace out the circuit, identify what pins are power, inputs and outputs, etc. That might tell you what chip it is but, assuming it is programmable, it won't help you much. I would expect to find a microcontroller in such a circuit.
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
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    chances are its a micro possibly a pic, or in house made chip, you wont get one to replace it, you are better off getting a new volume control system,

    you can post pics of the pcb any model number of the sytem, in case others have one to compare.
     
  5. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    After you throw it in the recycle bin, send a letter to the manufacturer explaining why you will never buy their crap products again...
     
  6. hp1729

    Well-Known Member

    Nov 23, 2015
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    Before you buy a system do you open it and see if it is constructed of such chips? I share your frustration about such unrepairable assemblies but I assume they are all made that way.
     
  7. dl324

    Distinguished Member

    Mar 30, 2015
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    I saw a case where someone started manufacturing an open source Willem EPROM programmer and sanded all of the part numbers from the IC's. The funny thing was that there were other designs that used the same schematic that didn't. It's a pain in the you know what to work on the one with sanded parts, but it wasn't long before someone posted an annotated component diagram.

    Then there was the guy who decided to make the software closed and started making hardware and software improvements that weren't compatible with the original design. He must have reasoned that he made so many improvements that it was okay for him to appropriate the work of others for his benefit. It wasn't long before the hardware changes were reverse engineered so older hardware could be made compatible with the new software.
     
  8. MikeML

    AAC Fanatic!

    Oct 2, 2009
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    It is one thing to sell something with hard-to-obtain parts or field-programmed parts. It is another to sand the part numbers off standard parts.
     
  9. ian field

    Distinguished Member

    Oct 27, 2012
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    Very occasionally they slip up and the original manufacturer has printed some clue on the underside of the chip.

    Many years ago, a friend needed a replacement for a house coded chip that drives the display in a calculator - that was back when calculators were pretty expensive.

    He'd traced it out and knew what the pins did - when I looked at his sketch, it struck me that the pinout was the exact reverse of one of the ULN darlington arrays - so we bent back the pins on one of those and fitted it, it worked.

    Searching for the schematic would enable trawling through the catalogues for a chip with the same functionality - its worth bearing in mind that there's a lot more product brands than manufacturers, so the service manual may only be available in the guise of for the original manufacturers product. Sometimes there's forums that can identify manufacturer from badge and model number.
     
  10. hp1729

    Well-Known Member

    Nov 23, 2015
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    Ah, patent protection versus just keeping secrets?
     
  11. dl324

    Distinguished Member

    Mar 30, 2015
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    The design was open source. In this case, I think it was just greed.
     
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