I think these are inductors about (100uH) used is series with the RS-422 lines to reduce noise. I don't think these are across the two lines ( not in parallel) . ----- Original Message ----- From: "Roger Weichert" To: "Microcontroller discussion list - Public." Sent: Wednesday, June 9, 2010 10:15:51 AM GMT -05:00 US/Canada Eastern Subject: ID Transient Voltage Protectors ? Hi guys, I am looking for some help please in identifying a couple devices used across an RS422 communications line on a board. Ther's a photo here ... http://imagebin.ca/view/UJfdCKe.html One device goes between one of the RS422 comms line and ground and the second one goes between the other comms line and ground. They look just like resistors, but obviously are not. They have what looks like a glass body with painted on rings. A bit like a large 1N4148. Out of circuit one measures 194 ohm both ways and the other about 35 Meg ohms both ways. (no fingers) I'm assuming they are varistors or transient voltage protectors of some sort, but have no idea on values or where to source a suitable replacement The board got damp and had a fair bit of corrosion around that area. Just out of interest, the 2R2 smd's that are visible in the photo are inductors, not resistors. You'd think manufacturers could come up with some markings that weren't so potentially confusing. Thanks, Roger -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist -- http://www.piclist.com PIC/SX FAQ & list archive View/change your membership options at http://mailman.mit.edu/mailman/listinfo/piclist