I have recently seen two situations where an apolLO I fails to lock, but does not appear to have a hardware issue. Upon investigation, I discovered that the EEPROM where the setup is stored (frequency, etc) has been overwritten in the first location. Specifically it has a 0xFF instead of an 0x23 in it. I am not currently check-summing the values or performing any other checks and so it causes bad data to get loaded into the synthesizer. This occurs for firmware 1.15 and earlier. I have updated the software to check to ensure that if a 0xFF is found, it is replaced with a valid 0x23. This is a temporary fix until I can find the root of the problem
I have not seen any other cases of this, but this could be because others assume they have damaged the board, etc. If you have a no-lock situation when you believe it should be locking and have made sure that it is not your 10MHz reference and a valid frequency/PFD (R and N) are in the board and would like to check for this problem, you have a couple of options:
1) If you have access to a Microchip programmer, you can check the first EEPROM location (0) and verify that it has a valid value. If it does not, you can reset the board to a factory state by writing 23 0D 70 04 00 00 00 0A 00 00 00 40 into the EEPROM starting at location (0). Be sure to read the entire program, view the EEPROM, update it and then perform a program. If you do not read the entire contents of the part first, you can write an empty program back into the part!
2) You can return to board to us and we will rewrite both the EEPROM and the updated software into the part and return the board to you.
If you have any questions, please feel free to drop me an email. Note that the apolLO-32 does not use the EEPROM and therefore cannot have this problem. All values are hard-coded in the software in the apolLO-32.