I have an old 2518-17 MPU I’d like to get working for a spare. After I received it I replaced all the brown sockets. It was previously modified per the Pinwiki to accept 2732 ROMs at U2 and U6 and I have verified the modification work. I’ve installed good chips at U6, U9, U11. There are no chips in U2, U7, U8, and U10. Powered up on the bench and LED is locked on. There is some abated corrosion, but I have confirmed good continuity checks on traces/components.
What I have tried:
Shorted pins 40 and 39 momentarily on the cpu chip; The LED did not turn off.
U9 Pin 40 measures 5V
Q1 and Q5 test good.
There is pulse on U9 pin 3, 36, and 37.
U9 pin 3, 36, and 37 measure 2.8V
U9 Pin 2 measures 5V.
U9 Pin 5 measures 2.8v
Can I please get some additional troubleshooting help?