I have an Alpha Metals Ionograph model 500M that I have inherited from an engineer that is no longer with the company. Along with this piece of equipment I have only inherited internal procedures that look like they have been copied from the manual, but no manual. We have to calibrate or verify the solution by taking a specific gravity and running the test procedure. in this you use the reading you have taken above and add a know amount of contaminate to the unit. I am then looking for a reading of 37.5 (+/- something I'm assuming) for a pass. the problem I am having is that I am reading in the 420's to 460's and no one here has ever seen this unit fail. we also do not cover the fail contingency in our procedures. I have been leaving messages with Alpha Metals for 2 days with no reply. Help!!!!!!!!!!!!!!!!!!!! Has anyone encountered this and if so could you give me some guidance. Bill Irwin [log in to unmask] Bill Irwin Berg Electronics (717) 764-7309 ################################################################ TechNet E-Mail Forum provided as a free service by IPC using LISTSERV 1.8c ################################################################ To subscribe/unsubscribe, send a message to [log in to unmask] with following text in the body: To subscribe: SUBSCRIBE TechNet <your full name> To unsubscribe: SIGNOFF TechNet ################################################################ Please visit IPC web site (http://jefry.ipc.org/forum.htm) for additional information. For the technical support contact Dmitriy Sklyar at [log in to unmask] or 847-509-9700 ext.311 ################################################################