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XGENUS X-ray repair - no sound.
In the XGENUS X-ray unit, the sound signal is activated by the U12 - ULN2003 microcircuit.
ULN2003 is a seven-channel switch on composite bipolar transistors based on 5 volt TTL logic.
Sound test with a multimeter:
The put the plus probe on 9 pin, the negative probe on 13 pin, from the digital tester, the ohmmeter limit is 2000 ohms. There should be a loud clear 2 kHz sound.
If there is sound, the buzzer works. Then replace the chip U12 - ULN2003.
U12 - ULN2003 also controls electromechanical relays.
Test ULN2003. Digital tester in ohmmeter mode at the limit of 2000 Ohms.
The resistance between the legs of the input / output should never be less than 2 kOhms.
Pin Input - Pin Output