PB 300/320 Motherboard Layout

Note

1. When replacing the motherboard and installing or removing a modem, ensure that the JMOD connector is configured properly.
To see how the JMOD connector works, use keyword "JMOD" to bring up the document "How does the JMOD Connector work?".
 
2. There are about 100 motherboards, similar to Motherboard A, that have 8 SIMM sockets; only four are enabled.
 
3. There are three revisions to this motherboard.
 
Motherboard A has 1MB surface mount DRAMs upgradable to 5MB.
Motherboard B does not have surface mount DRAMs upgradable to 16MB.
Motherboard C has 2MB surface mount DRAMs; CPU is 16, 20 or 25MHz.
 
 
Motherboard A
Motherboard B
Motherboard C
 
 
Sockets
Jumpers
Connectors