Ok. I'd focus on U1 to U9. In fact, I'd focus on U1.
Print out the first page of the datasheet. Make a worksheet for the 14 pins of JP1, noting that pin 1 is indicated by a tiny triangle on the connector shroud, or sometimes by a square pad on the PCB.
Here's a diagram:
http://www.equinox-tech.com/products/details.asp?ID=360
You can just write number 1 to 14 then use a multimeter in continuity mode to figure out where the pins actually go. You can also write numbers 1 to 16 for U1 and write the same information from the "other end".
I'd start with power (VCC), pin 16, on U1, and GND, pin 8. Put one multimeter probe on the pin on the chip. Careful because the pins are very small and narrow. Then touch the other multimeter probe to all the pins of JP1, and write down which ones caused a beep. I'd expect there to be only one for power and one for GND.
D0 to D7 are the chip inputs, and undoubtedly come from the switches. We can ignore that for now and test it later.
Using the multimeter find out where pins 1, 2, 7, 9, 10, and 15 go. They might not be connected to anything. Or they might not be connected to JP1.
Now look at the switches. They will be connected to D0 to D7 on U1, and also to the long, thin, flat things. Those are resistor packs. They have 9 pins, which are for 8 resistors and a common pin. Use the meter to figure out which pin on U1 is connected to the resistor pack (probably the nearest one). That deals with 8 pins, so use the meter to find where the ninth pin goes. It will be power or GND.
That's enough for now. Please report your findings.
Print out the first page of the datasheet. Make a worksheet for the 14 pins of JP1, noting that pin 1 is indicated by a tiny triangle on the connector shroud, or sometimes by a square pad on the PCB.
Here's a diagram:
http://www.equinox-tech.com/products/details.asp?ID=360
You can just write number 1 to 14 then use a multimeter in continuity mode to figure out where the pins actually go. You can also write numbers 1 to 16 for U1 and write the same information from the "other end".
I'd start with power (VCC), pin 16, on U1, and GND, pin 8. Put one multimeter probe on the pin on the chip. Careful because the pins are very small and narrow. Then touch the other multimeter probe to all the pins of JP1, and write down which ones caused a beep. I'd expect there to be only one for power and one for GND.
D0 to D7 are the chip inputs, and undoubtedly come from the switches. We can ignore that for now and test it later.
Using the multimeter find out where pins 1, 2, 7, 9, 10, and 15 go. They might not be connected to anything. Or they might not be connected to JP1.
Now look at the switches. They will be connected to D0 to D7 on U1, and also to the long, thin, flat things. Those are resistor packs. They have 9 pins, which are for 8 resistors and a common pin. Use the meter to figure out which pin on U1 is connected to the resistor pack (probably the nearest one). That deals with 8 pins, so use the meter to find where the ninth pin goes. It will be power or GND.
That's enough for now. Please report your findings.
Statistics: Posted by ame — Mon May 06, 2024 1:47 am