thanks to everyone for their response! result: it's a Burr Brown 3500 op amp I replaced it with a TL072 and all is well. again, thanks for all the responses. -phil << > Hi, > I'm trying to find a pin for pin replacement IC for what looks like an Op Amp: > 3B 3500 > It has 8-pins. > Thanks for any help! > best, > phil >>