Mettler Toledo Safeline MD old industrial metal detector - JED firmware dump

[florin1up]

Hello everyone. I have a big problem with an old Safeline Mettler Toledo Metal detector model MD assembled by sassib Packaging Italy. (picture)

The fault is on the CPU board (see picture). I know that because I had 2 units: one good and one faulty. I swiched the boards between them and after I saw that the CPU board is faulty, I switched the CPUs between the boards (HD63b09). That looks like was a really bad ideea because now, both cpu boards have the same problem - no text on lcd, no detection, nothing but some leds on).

Looks like, somehow the programmable logic array (U9 = PALCE16v8h - with the white label "DEC 3" ) has been corrupted. I came to this conclusion after I bought and tested all the IC's from that board. The eeprom is ok (I have read it before switching the procesors). Maybe with some luck someone have a good or faulty board? or I need the JED or BIN dump file from the U9 chip.

I am in trouble because the working PCB died in my hands. This board has more than 20 years old and I guess when I heated up the pins (max 200 degrees C) in order to change the CPU, the heat "helped" the PAL logic array to "forgot" his program (in datasheet, the Pattern Data Retention Time is @10 years).

I made the schematic and the chip enable pin of the RAM and EEPROM are connected to this logic array.

Other info:
- I programmed the PALCE chip with some random data and sometimes the watch dog led blinks.
- I have many years of experience in soldering and good tools, so the circuits have not been damaged (also I tested 98% of circuits)
- I have the option to unlock the security bit of PALCE16v8 chip, I attached the dump file(changed to  .txt) Unfortunately I read the chip after problem occured.
- The PALCE from the other board, after I unlocked it, gives me a different code at every reading so I guess this is faulty too.

Any sugestions?
Thank you !