Timer is the important circuit of medical x-ray machine. Once it appears fault, little problem will affect quality and larger will lead to X ray tube damage. Beause there are all kinds of timers, the phenomenons and reason of failures are different. So now, Here make the common faults of timer for a example and introduce beakdown maintenances of the others timer.

Common breakdown maintenances of timer

Electronic timer has electronic tube timer, brake flow pipe timer, transistor timer and Integrated circuit timer. Now, we will introduce common fault and repairing methods of transistor timer.

Firstly, transistor failure; No matter transistor, diode or Silicon controlled sngle junction transistor, there are two common failures, one is punctured and the other is internal open, they will make the control circuit can't work normally. Now you can observe work condition of limit relay and measure it. Then you need to exchange same model or alternative type of new tube.

Secondly, RC circuit fault. RC circuit is the basic circuit of timer and its main faliures have following several:

(1)     Capacitor breakdown or open: it will lead to RC loop or short circuit and transistor can't work normally. Timer cann’t limit or limit constantly.

(2)     Capacitor leakage

(3)     Resistance open or demage

(4)     Resistance tolerance change: It makes RC constant change and lead to limit delay and reduce and make limit inaccurate.

Thirdly, high sensitive relay fault

(1)     Coil open or demage

(2)     Contact fault

Fourth, timer examination process:

(1)     Take down high pressure primary connection and make sure that whether every grade limit appear same fault or not.

(2)     Make sure that whether timer supply power exchange input voltage is normal or not.

(3)     Ensure that after rectifying dc power voltage is normal or not.

(4)     Make sure that bottom line,is high sensitive relay working condition having any abnormalities?

(5)     Measure every grade work voltage is normal.

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