I have a vixen DD-2 telescope controller, which is not working. In my cases the LED on the controller doesn't lighting up. The controller remote is rated 12V/ 0.96A.

I have confirmed the capacities of all the capacitors and the voltage at points A to E:

A : 12.1V
B : 12.1V
C : 0.5V
D: 0.9V
E: 1.8V

Further, I have confirmed the two diodes D1 and D3.

Not in the picture is a Linear Voltage Regulators (L7805CV, 5.0V 1.0A) to which the three cables (IN: yellow, GND: black, OUT: green) lead.
Linear Voltage Regulators info : https://www.mouser.com/datasheet/2/389/l78-974043.pdf

I could not figure out what the large element at bottom called Y1 (ZGC 2.52345) is.

I know it is a difficult question, but if somebody has time, I would be very happy about any ideas, or guidance on how to figure out why the LEDs don't light up and why the controller remote is not working.

Thank you very much.

 

Y1 appears to be a crystal for an oscillator.

 

Thank you very much for the quick response. This already helps a lot.

From what I have read so far from google is, that quartz crystals are more or less likely to fail.
However, I have no idea how to check, whether the crystal is defective. Further, I have no idea how to figure out, what kind of crystal it is ....

 

Occasionally, moisture or just atmospheric humidity can infiltrate parts such as slide switches. Try using electronic contact cleaner ... the spray can type ... on the slide switches, then cycle them a few times. ... Maybe even on the resistor trimmer adjustments. There seems to be inadequate voltage across the led.
... Make sure the external wires that are soldered to the board are not partially broken at the attachment points ... a common problem.

 

The frequency is stamped on the crystal and they are not very prone to failure. It will take a frequency meter or an oscilloscope to test it but I would put it very low on the possible faults list.