Guest tresguey Posted August 13, 2014 Report Share Posted August 13, 2014 I need help identifying a chip on a board I am trying to repair. The board triggers two relays based on temperature. One at a set temperature based on where you have the pot calibrated. The other relay is triggered 10 degree warmer. I checked everything on the board and tested fine. So it must be the chip. I did see a similar circuit using a lm741 and tried soldering one in, but did not function at all. Is there an easy way to identify what this chip might be? Quote Link to comment Share on other sites More sharing options...
Guest liquibyte Posted August 13, 2014 Report Share Posted August 13, 2014 From what I can see of the top of the chip, it looks like it's had the markings sanded off so it may be hard to identify without at least that basic information. Maybe someone in the industry will chime in here (hopefully). Quote Link to comment Share on other sites More sharing options...
Guest tresguey Posted August 13, 2014 Report Share Posted August 13, 2014 Yes, they were. I guess someone did not want anyone to know what was used. Quote Link to comment Share on other sites More sharing options...
Guest liquibyte Posted August 13, 2014 Report Share Posted August 13, 2014 Pin 8 doesn't seem like it's connected to anything. I can't tell if pin 2 is on top because of shadows but it isn't on the bottom. Those are clues but, admittedly, not good ones. Sometimes you can wet the top of these and use a bright light to see impressions and glean some of the markings but it appears, at least in this image, that they did a thorough job of obfuscation. Quote Link to comment Share on other sites More sharing options...
Guest tresguey Posted August 14, 2014 Report Share Posted August 14, 2014 You are correct, there is nothing connected to pins 2 and 8. Quote Link to comment Share on other sites More sharing options...
Guest tresguey Posted August 15, 2014 Report Share Posted August 15, 2014 I was wrong, pin 2 is connected to R3 from the topside, then goes to R5 which is then connected to ground and one leg of the 47k thermistor. Quote Link to comment Share on other sites More sharing options...
Guest liquibyte Posted August 15, 2014 Report Share Posted August 15, 2014 I was wrong, pin 2 is connected to R3 from the topside, then goes to R5 which is then connected to ground and one leg of the 47k thermistor.Feel up to trying to draw a schematic from the board? That might help in trying to identify the chip based on the design. Quote Link to comment Share on other sites More sharing options...
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