ULN 2803A CHIPS
Hello all, I am new to this forum. I have a JW board MTP-8. I have recently blown a ULN 2803A chip. After reading some of the other posts on this forum I see it is possible to replace this. Where can I obtain replacement chips living here in the U.S. without having to buy a bulk quantity?? Ive have found them on several microprocessor sites but it is a quantity purchase. Also, any other advice related to this would be helpful. The board worked fine, I am wondering if moisture or condensation from the cool weather we have been having caused this to happen. The organ I have built has been stored in a garage...Just wondering. Thanks for all replies Chris Ayers Paducah, Ky

Hi, Chris Ayers http://cpc.farnell.com/jsp/home/homepage.jsp You will find most components here. I use them every day well all most. They ship all over the world. Just type the IC number in the search engine on the home page. Hope that helps if not re-post on imod. I can order them for you and post on if necessary. phil radford

Arrow www.arrownac.com - they have 3,325+ in stock !! at $0.55 each. Digikey http://www.digikey.com/scripts/DkSearch/dksus.dll?Detail?Ref=223167&Row=193502&Site=US I tried www.newark.com but they only had the SOIC version. Newark is Farnell's American arm. Stephen

ULN 2803A
I have had real good results from the board so far. I may have made the mistake of not encasing it to protect it from the elements (sawdust, dirt, cold air etc.) What precautions do I need to take when inserting a new chip (for those of you that have done this)? The socket & bus bar took some heat, but they look ok. When this happens, is the damage usually limited to just the chip?? Stephen, what does SOIC mean?? Other than the ULN number, are there any other identifiers for this chip that I would need to order it? Thanks for the replies. Chris Ayers

Other than the ULN number, are there any other identifiers for this chip that I would need to order it? No just bang "ULN2803A" into any of the websites I mentioned and it will come up with an order page for you I think. These are pretty common chips for hobbyists. They don't like being overloaded though. tephen, what does SOIC mean?? SOIC is the surface mount version of the chips as opposed to the DIP version (Dual-In-Line) which is what you probably have. To remove DIPs from their socket, take a small flat-blade screwdriver and gently prise up one end of the chip and then the other. Keep doing this until the chip is free. Don't do what I did the first time I removed a DIP from its socket and pull it with your fingers. You'll end up with bent pins and probably some chip-legs stuck in your fingers !! Make sure the power is off before you do this (obvious !! :-)) and try not to touch the pins too much. I think you'll have a hard time 'zapping' these chips with your body though. Make sure you remember which way round the chip goes in the board for when you put the new one in. I would order plenty of spares. If there are multiple chips on the board, I would remove them all and put in the new ones one at a time and -*test*-('") them - that way if it's some kind of global fault which has fried them, you won't destroy them all at once. Stephen

ULN 2803A CHIPS
Thanks for the tips, The chip blew up on the outer edge near the bus bar, smoked it pretty good. Funny thing is, there nothing connected to that side of the board.

Hello Chris I think I can say I'm now a specialist of blowing up ULN 2803a on J Wale Midi card! If nothing was wired to the chip blown, and only this one is blown, certainly you inverse polarity...I did the same, for same result! Beware also not to have more than 2 amps on a group of 8 ports... So, perhaps it's better to order a few ULN's!!!! Chris, from France