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The SAMS schematic for the 600B shows that pin 20 of the monitor rom (U13) should go to ground while pin 21 should go to phi2 or /phi2 at W6. The OSI schematic shows that 21 goes to 5V and 20 goes to W6. However on my old board pin 21 and 20 are connected via a short wire jumper on the back of the board and then to W6. Has anyone else got a unit they could take a quick look at to verify which is correct?

Pin 20 and 21 are bridged on the bottom of the board on my unit. They then go to W6 as a single trace.

/Jeff

Thanks for confirming Jeff.

So both schematics are wrong.