I traced down all connections I could find and came up with this:
Code: Select all
74'161
.--\/--.
+5V --|01 16|-- +5V
PRG R/W --|02 15|-- NC
PRG D0 --|03 14|-- PRG A15
PRG D1 --|04 13|-- PRG A16
PRG D2 --|05 12|-- CHR A13
PRG D3 --|06 11|-- CHR A14
GND --|07 10|-- GND
GND --|08 09|-- '138 Pin 7
`------'
74'138
.--\/--.
PRG A12 --|01 16|-- +5V
PRG A13 --|02 15|-- NC
PRG A14 --|03 14|-- NC
NC --|04 13|-- NC
PRG R/W --|05 12|-- NC
PRG /CE --|06 11|-- NC
'161 Pin 9 --|07 10|-- NC
GND --|08 09|-- NC
`------'
This is what I did:
Desoldered original CHR, PRG ROM as well as 74'161.
Split Crime Busters into CHR (27c256) and PRG (27c040, didn't have a 27c010).
Soldered in the CHR directly (A13 and A14) go to the 74'161 anyway and are present, which is good.
For PRG I bend up pins 1,2,3,22,24,30,31,32
Pin 1 is NC
Pin 2 goes to 74'161 pin 13 (A16)
Pin 3 goes to 74'161 pin 14 (A15)
Pin 22 goes to hole 24 (PRG ROM /CE)
Pin 24 goes to GND (/OE)
Pin 30 and 31 are NC
Pin 32 goes to hole 28 (VCC)
A14 was not connected directly to the connector, I changed that, too.
Tried connecting pin 30 (A17) to VCC as well, no difference.
For the 74'161 I bend up pins 2,5,6,9,11,12,13 and 14. All other pins connect to the board.
The game stays black. Anyone know what could be wrong?
Also, the original board has a 4.7k Ohm resistor if I'm not wrong and a capacitor. What could they be used for? Are they neccessary? Thanks!