Legible schematic of motherboard?

From: snhirsch <snhirsch_at_email.domain.hidden>
Date: Fri, 15 Apr 2011 19:21:24 -0700 (PDT)


Does anyone have a readable copy of the motherboard schematic? I found one in the Lisa technical manual PDF, but it's largely illegible. It also appears incomplete. I'm trying to troubleshoot a no-display problem after replacing the wiring harness. I have raster with the brightness cranked up which means high-voltage, hsync and vsync are being delivered. I also have video at the RCA jack on the rear panel. That narrows it down quite a bit. The schematic shows two transistors that buffer the RCA composite output and (I think) blend in sync. However, the PCB has a TTL chip near the power/video connector that I cannot locate on any of the schematics. I _think_ this chip is part of the "fade out" logic, but need to understand a bit more about the circuit.

Can anyone help? 

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Received on 2011-04-15 20:10:36

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