TC reported fire external at Rear M1 car. Staff (AMK) checked and confirmed, no abnormalities. T201 line clear and feedback no abnormalities. ~~~~~ 1557 TC reported fire external. Staff (AMK) confirmed, no abnormalities. T201 line clear and feedback no abnormalities. CE : T204-1557 Smoke External Alarm Reset. Fault Cleared.     1557 FC 721. Swop SDR-11 from car #1557 to #2557 for monitoring. Checked Smoke Detector, no cable gland. Gasket checked ok, no damaged. Base of smoke detector dry. Ops 20 raised to changeout #2 end smoke detector.  Aliff/Redzwan 45210 BSD: 1557 No 2 End -  To C/O Smoke Detector