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

1-16
2-15
3-14
4-13
5-12
6-11
7-10