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Sega Model 3 Step 2.0 Repair Guide

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The work on my Sega Rally 2 has extended out a bit to more of a general Sega Model 3 Step 2.0/2.1 repair exercise.


I've had to reverse engineer quite a bit of stuff to work out what was going on and couldn't find that information anywhere on the internet.


So I thought I'd put together a bit of a guide.


It covers quite a bit of stuff and has photos of what happens when various components fail (basically all ram at this stage). It also includes which ones to actually replace (some of the memory test results actually refer to step 1.5 IC's that don't exist on the step 2.0 board).


I've also done some reverse engineering on the JTAG bus, its role in boot up failures and some insights on how to interpret the boundary scan results.


I've done it as a google doc just to make it easy to update




Happy to take any feedback and/or corrections.

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Cool thanks. I’ve got a number of updates to do. I’ll get to them at some stage hopefully soon.


Hi. Your manual has helped me for repairing a Model 3 Step 2.0 with IC12 error. Many many thanks for that.


Now I have another one with depth buffer error. I have seen that IC61 is a buffer memory, and already exists in the motherboard. It's under IC12. Have you repaired one of this kind? The IC62 memory is very expensive.


It also has "Texture Memory 11" error (IC63,IC64,IC65,IC66,IC67,IC75,IC80,IC81). Do you know that error?

Edited by Tailsnic
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