midsomerjambo

A friend of mine who's into ceramics gave me an old digital pyrometer supplied by Potterycrafts Ltd. (model LCI/PTY serial no. 91-00793) to try and fix. The model/serial number label on the base of the box has the name of The Industrial Pyrometer Co Ltd. The sensor is labeled SBS Eng Services with a London telephone number. The type is 7/6P10/0.3R-F and serial no. is 11979. At room temperature without the sensor connected, the display reads around 1575C. On attaching the sensor to the box, the display increases to around 1650 but if I heat it with a gas burner, nothing further happens. The display segments all work correctly so that leads me to think the A-D converter is working, at least to an extent. Would anyone have any information that might help me to get it working properly? If you'd be willing to help, I can send photos if that's of assistance. Best regards, Gerry Frew